Definitions — Marjon Willekens

Let’s start with our fourth Earthshot: ‘Fixing our climate’. This one is all about possibly the most debated challenge related to the health of our planet: global warming. The objective that was formulated ten years ago to keep this phenomenon in check, is written in the Paris Agreement. In this blog I explain what it entails.
The basis might be familiar to you: we have agreed that the global temperature on earth will not rise more than 2 °C by the end of this century compared to the average global temperature from before the industrial revolution. Efforts are made to limit the temperature increase to 1.5 °C.
This agreement was concluded at the COP21 in Paris on December 12th 2015 and came into effect on November 4th 2016. There are 195 participating parties. These are the European Union and all members of the United Nations except Iran, Libya and Yemen.
There are thus many enthusiasts.
One party is fickle: the United States of America. As many others they were part of the first batch of ratifiers who signed the agreement on April 22nd 2016 (Obama II government) in New York. On November 4th 2020 they however officially redrew from the agreement (Trump I) to reenter only three months later, on January 20th 2021 (Biden government). Four years later, on January 20th 2025, it was officially announced that they will again redraw (Trump II government). This withdrawal will go into effect on January 20th 2026.
Until now no other party – and let’s keep it that way – has pulled a similar trick. And if it was not this poignant that the second largest emitter of greenhouse gasses in the world (11% in 2023) decides not to make an effort to limit global warming, I might be able to see the hilarity of this toxic on-again-off-again, relationship.
So much for the disappointment. Let it be clear that the other parties remain determined. They continue to build towards a beautiful future for humankind on this planet.
The execution of the plans goes as follows.
The global warming that has been measured and observed over the past 150 years is the consequence of excessive emission of greenhouse gasses related to human activity. To reach the goal described in the Paris Agreement these emissions need to be restricted. So while the objective of the treaty focusses on the consequence of the problem (global warming), the parties are responsible to address the cause (greenhouse gas emissions).
To assure this objective is being worked on systematically, every five years each party submits their ‘Nationally Determined Contributions’ (NDCs). This overview describes which actions the party will take to limit the greenhouse gas emissions as well as which measures are instated to adapt to the consequences of climate change. The first set of NDCs was submitted by all parties in 2020. If all measures described in these NDCs are correctly executed, it was calculated that the earth will be 2.1 – 2.8 °C warmer by the end of this century compared to before the industrial revolution. Let it be clear that this is not in line with the Paris Agreement. It is however better than the global warming of minimally 4 °C that was predicted in case the NDCs are not executed.
This year the first cycle closes which means that the second set of NDCs will be proposed on the COP30 in November 2025 in Brazil. The parties are expected to formulate each cycle more ambitious goals – for this they are counting on light group pressure. This new package of more progressive measures should thus (if consistently executed) bring us closer to a maximal global warming of 2 °C by the end of the century.
It goes without saying that the advancement on these plans needs to be monitored. How this is practically managed was formalized at the COP24 in 2018 in Poland: every five years data on the state of the climate is gathered and summarized on the ‘Global Stocktake Platform’ (GSP). The collection of the information package happened for the first time in 2023. The next ‘Stocktake’ is planned for 2028.
The Paris Agreement also includes a framework that states that developed countries support developing countries financially and technologically to reach the climate objective. Financially this means that between 2020 and 2025 yearly 100 billion euros should flow from developed to developing countries to assure they can invest in reducing greenhouse gas emissions and in adapting to climate change impact. From 2025 onwards this yearly budget will be increased and at the COP29 is was agreed that by 2035 this yearly fund should be 300 billion dollars. No fixed financial contribution per participating developed country is listed, the fund is built on a ‘give-what-you-can’ principle. In 2020 and 2021 this led to a fund size of respectively 83.3 and 89.6 billion USD. In 2022 the 100 billion USD goal was surpassed with a fund of 115.9 billion USD.
The USA officially states this ‘economic burden’ as the reason to retreat from the Agreement.
There is no doubt that this Paris Climate Agreement is of enormous value. The long participant list shows common understanding of the necessity to limit global warming and the mobilized fund facilitates that also developing countries can make their indispensable contribution. And however the assignment is in no way an easy one, I have high hopes we will, as citizens of this earth, succeed at it. We are already in any case – compared to the unacceptable inaction – moving into the right direction.

SOURCES:
N.N.; The Paris Agreement; URL: https://www.un.org/en/climatechange/paris-agreement ; accessed on March 9th 2025
N.N.; The Paris Agreement; URL: https://unfccc.int/process-and-meetings/the-paris-agreement ; accessed on March 9th 2025
N.N.; Paris Agreement; URL: https://en.wikipedia.org/wiki/Paris_Agreement ; accessed on March 9th 2025
KRONENBERG Alan; What is the Paris Climate Agreement, and What Happens When Trump Pulls America Out of IT?; URL: https://www.usnews.com/news/national-news/articles/2025-01-22/what-is-the-paris-climate-agreement-and-why-does-trump-want-to-pull-the-u-s-out-of-it ; Januari 22nd 2025
TISEO Ian; GHG emissions in the U.S. – statistics & facts; URL: https://www.statista.com/topics/3185/us-greenhouse-gas-emissions/#topicOverview ; March 5th 2025
N.N.; Global Stocktake; URL: https://unfccc.int/topics/global-stocktake ; accessed on March 9th 2025
N.N.; Outcome of the First Global Stocktake; URL: https://unfccc.int/topics/global-stocktake/about-the-global-stocktake/outcome-of-the-first-global-stocktake ; accessed on March 9th 2025
N.N.; Climate Finance and the USD 100 billion goal; URL: https://www.oecd.org/en/topics/sub-issues/climate-finance-and-the-usd-100-billion-goal.html ; accessed on March 9th 2025
POMPEO Michael R.; On the U.S. withdrawal from the Paris Agreement; URL: https://2017-2021.state.gov/on-the-u-s-withdrawal-from-the-paris-agreement/ ; November 4th 2019

Blog 16 - Explain to me the Paris Agreement

Let’s start with our fourth Earthshot: ‘Fixing our climate’. This one is all about possibly the most debated challenge related to the health of our planet: global warming. The objective that was formulated ten years ago to keep this phenomenon in check, is written in the Paris Agreement. In this blog I explain what it entails.

The basis might be familiar to you: we have agreed that the global temperature on earth will not rise more than 2 °C by the end of this century compared to the average global temperature from before the industrial revolution. Efforts are made to limit the temperature increase to 1.5 °C.

This agreement was concluded at the COP21 in Paris on December 12th 2015 and came into effect on November 4th 2016. There are 195 participating parties. These are the European Union and all members of the United Nations except Iran, Libya and Yemen.
There are thus many enthusiasts.

One party is fickle: the United States of America. As many others they were part of the first batch of ratifiers who signed the agreement on April 22nd 2016 (Obama II government) in New York. On November 4th 2020 they however officially redrew from the agreement (Trump I) to reenter only three months later, on January 20th 2021 (Biden government). Four years later, on January 20th 2025, it was officially announced that they will again redraw (Trump II government). This withdrawal will go into effect on January 20th 2026.
Until now no other party – and let’s keep it that way – has pulled a similar trick. And if it was not this poignant that the second largest emitter of greenhouse gasses in the world (11% in 2023) decides not to make an effort to limit global warming, I might be able to see the hilarity of this toxic on-again-off-again, relationship.

So much for the disappointment. Let it be clear that the other parties remain determined. They continue to build towards a beautiful future for humankind on this planet.
The execution of the plans goes as follows.

The global warming that has been measured and observed over the past 150 years is the consequence of excessive emission of greenhouse gasses related to human activity. To reach the goal described in the Paris Agreement these emissions need to be restricted. So while the objective of the treaty focusses on the consequence of the problem (global warming), the parties are responsible to address the cause (greenhouse gas emissions).

To assure this objective is being worked on systematically, every five years each party submits their ‘Nationally Determined Contributions’ (NDCs). This overview describes which actions the party will take to limit the greenhouse gas emissions as well as which measures are instated to adapt to the consequences of climate change. The first set of NDCs was submitted by all parties in 2020. If all measures described in these NDCs are correctly executed, it was calculated that the earth will be 2.1 – 2.8 °C warmer by the end of this century compared to before the industrial revolution. Let it be clear that this is not in line with the Paris Agreement. It is however better than the global warming of minimally 4 °C that was predicted in case the NDCs are not executed.
This year the first cycle closes which means that the second set of NDCs will be proposed on the COP30 in November 2025 in Brazil. The parties are expected to formulate each cycle more ambitious goals – for this they are counting on light group pressure. This new package of more progressive measures should thus (if consistently executed) bring us closer to a maximal global warming of 2 °C by the end of the century.

It goes without saying that the advancement on these plans needs to be monitored. How this is practically managed was formalized at the COP24 in 2018 in Poland: every five years data on the state of the climate is gathered and summarized on the ‘Global Stocktake Platform’ (GSP). The collection of the information package happened for the first time in 2023. The next ‘Stocktake’ is planned for 2028.

The Paris Agreement also includes a framework that states that developed countries support developing countries financially and technologically to reach the climate objective. Financially this means that between 2020 and 2025 yearly 100 billion euros should flow from developed to developing countries to assure they can invest in reducing greenhouse gas emissions and in adapting to climate change impact. From 2025 onwards this yearly budget will be increased and at the COP29 is was agreed that by 2035 this yearly fund should be 300 billion dollars. No fixed financial contribution per participating developed country is listed, the fund is built on a ‘give-what-you-can’ principle. In 2020 and 2021 this led to a fund size of respectively 83.3 and 89.6 billion USD. In 2022 the 100 billion USD goal was surpassed with a fund of 115.9 billion USD.
The USA officially states this ‘economic burden’ as the reason to retreat from the Agreement.

There is no doubt that this Paris Climate Agreement is of enormous value. The long participant list shows common understanding of the necessity to limit global warming and the mobilized fund facilitates that also developing countries can make their indispensable contribution. And however the assignment is in no way an easy one, I have high hopes we will, as citizens of this earth, succeed at it. We are already in any case – compared to the unacceptable inaction – moving into the right direction.

SOURCES:
N.N.; The Paris Agreement; URL: https://www.un.org/en/climatechange/paris-agreement ; accessed on March 9th 2025
N.N.; The Paris Agreement; URL: https://unfccc.int/process-and-meetings/the-paris-agreement ; accessed on March 9th 2025
N.N.; Paris Agreement; URL: https://en.wikipedia.org/wiki/Paris_Agreement ; accessed on March 9th 2025
KRONENBERG Alan; What is the Paris Climate Agreement, and What Happens When Trump Pulls America Out of IT?; URL: https://www.usnews.com/news/national-news/articles/2025-01-22/what-is-the-paris-climate-agreement-and-why-does-trump-want-to-pull-the-u-s-out-of-it ; Januari 22nd 2025
TISEO Ian; GHG emissions in the U.S. – statistics & facts; URL: https://www.statista.com/topics/3185/us-greenhouse-gas-emissions/#topicOverview ; March 5th 2025
N.N.; Global Stocktake; URL: https://unfccc.int/topics/global-stocktake ; accessed on March 9th 2025
N.N.; Outcome of the First Global Stocktake; URL: https://unfccc.int/topics/global-stocktake/about-the-global-stocktake/outcome-of-the-first-global-stocktake ; accessed on March 9th 2025
N.N.; Climate Finance and the USD 100 billion goal; URL: https://www.oecd.org/en/topics/sub-issues/climate-finance-and-the-usd-100-billion-goal.html ; accessed on March 9th 2025
POMPEO Michael R.; On the U.S. withdrawal from the Paris Agreement; URL: https://2017-2021.state.gov/on-the-u-s-withdrawal-from-the-paris-agreement/ ; November 4th 2019

I discovered something.
We are in the midst of the ‘UN Decade of Ecosystem Restoration’. This initiative started on June 5th 2021 (yearly World Environment Day) and runs until the end of the decennium. It is the United Nations’ aim to create political momentum for the recovery of ecosystems.
I was wondering.
Why had I never heard of this before? Even though the concept is pretty vaguely defined, it seems to be an initiative that deserves a spotlight. Other interesting programs are ongoing as well.
A more actionable plan is the ’30 by 30’ objective. This is one of the 23 targets defined, together with 4 goals, in 2022 at the COP15 (the biodiversity convention of the United Nations). The target states that by 2030 at least 30% of the terrestrial land, inland waters and marine areas need to be protected. The level of protection ranges from a total absence of human interaction to sustainable exploitation of the natural resources. Key is to guarantee that biodiversity can flourish and, if required, recovers. Especially areas of particular importance for biodiversity and/or areas that deliver specific ecosystem functions and services to nature and people should be selected.
Without going into too much detail I share the current status. The Protected Planet Report of 2024 reports that 17.6% of land and inland waters are protected. The protection of ocean and coastal areas is lagging even more behind: 8.3% of the ocean surface is registered as Marine Protected Area (MPA), while it is estimated that only 2.8% is protected effectively.
It is clear: there is still a lot of work to be done.
In the meantime a group of scientists and activists is already looking beyond the end of this decennium. The ‘Nature needs half’ movement advocates for an extension of ’30 by 30’ that assures protection of half of the planet by 2050. The protected areas should be distributed correctly over the different ecoregions so that the unique biodiversity that is sustained in different planetary regions, is adequately protected.
That’s that. We are up to speed again.
I find it important to be aware of the ongoing official programs and their objectives. At the same time it is at least equally important to understand that these are merely frameworks. They guarantee the protection projects’ right to exist and assure in some cases (partial) funding thereof.
However, if these frameworks are not met with specific protection and restoration initiatives such as for example the Cabo Pulmo Project from Blog 4, the Yellowstone Wolf Project from Blog 12 or the Rewilding Europe aspirations from Blog 13, they are pointless. The stories that color the canvas are the ones I prefer to focus on: the work actually performed. If we take the time to discuss these together then it does not seem so bad that we have never heard of the ‘UN Decade of Ecosystem Restoration’ before.

SOURCES:
RITCHIE Hannah; 2024; Not the End of the World, How We Can Be the First Generation to Build a Sustainable Planet; p. 221 – 222; Publisher Penguin Random House; UK
N.N.; About the UN Decade; URL: https://www.decadeonrestoration.org/about-un-decade ; accessed on February 22nd 2025
N.N.; UN Decade on Ecosystem Restoration; URL: https://en.wikipedia.org/wiki/UN_Decade_on_Ecosystem_Restoration ; accessed on February 22nd 2025
N.N.; 30 by 30; URL: https://en.wikipedia.org/wiki/30_by_30 ; accessed on February 22nd 2025
N.N.; Kunming-Montreal Global Biodiversity Framework; URL: https://en.wikipedia.org/wiki/Kunming-Montreal_Global_Biodiversity_Framework ; accessed on February 22nd 2025
N.N.; Just 2.8% of the World’s Ocean is protected “Effectively”; URL: https://www.bloomberg.org/press/just-2-8-of-the-worlds-ocean-is-protected-effectively ; accessed on February 22nd 2025
N.N.; COP15: Nations adopt four goals, 23 targets for 2030 in landmark UN biodiversity agreement – Official CBD Press Release – 19 December 2022, Montreal; URL: https://www.cbd.int/article/cop15-cbd-press-release-final-19dec2022 ; accessed on February 23rd 2025
N.N.; World must act faster to protect 30% of the planet by 2030; URL: https://www.unep.org/news-and-stories/press-release/world-must-act-faster-protect-30-planet-2030 ; accessed on February 23rd 2025
N.N.; Nature needs half; URL: https://natureneedshalf.org/ ; accessed on February 22nd 2025
DINERSTEIN E.; An Ecoregion-Based Approach to Protecting Half the Terrestrial Realm; BioScience Vol. 67 No. 6; June 2017

Blog 15 - The frameworks of biodiversity recovery

I discovered something.
We are in the midst of the ‘UN Decade of Ecosystem Restoration’. This initiative started on June 5th 2021 (yearly World Environment Day) and runs until the end of the decennium. It is the United Nations’ aim to create political momentum for the recovery of ecosystems.

I was wondering.
Why had I never heard of this before? Even though the concept is pretty vaguely defined, it seems to be an initiative that deserves a spotlight. Other interesting programs are ongoing as well.

A more actionable plan is the ’30 by 30’ objective. This is one of the 23 targets defined, together with 4 goals, in 2022 at the COP15 (the biodiversity convention of the United Nations). The target states that by 2030 at least 30% of the terrestrial land, inland waters and marine areas need to be protected. The level of protection ranges from a total absence of human interaction to sustainable exploitation of the natural resources. Key is to guarantee that biodiversity can flourish and, if required, recovers. Especially areas of particular importance for biodiversity and/or areas that deliver specific ecosystem functions and services to nature and people should be selected.

Without going into too much detail I share the current status. The Protected Planet Report of 2024 reports that 17.6% of land and inland waters are protected. The protection of ocean and coastal areas is lagging even more behind: 8.3% of the ocean surface is registered as Marine Protected Area (MPA), while it is estimated that only 2.8% is protected effectively.
It is clear: there is still a lot of work to be done.

In the meantime a group of scientists and activists is already looking beyond the end of this decennium. The ‘Nature needs half’ movement advocates for an extension of ’30 by 30’ that assures protection of half of the planet by 2050. The protected areas should be distributed correctly over the different ecoregions so that the unique biodiversity that is sustained in different planetary regions, is adequately protected.

That’s that. We are up to speed again.
I find it important to be aware of the ongoing official programs and their objectives. At the same time it is at least equally important to understand that these are merely frameworks. They guarantee the protection projects’ right to exist and assure in some cases (partial) funding thereof.
However, if these frameworks are not met with specific protection and restoration initiatives such as for example the Cabo Pulmo Project from Blog 4, the Yellowstone Wolf Project from Blog 12 or the Rewilding Europe aspirations from Blog 13, they are pointless. The stories that color the canvas are the ones I prefer to focus on: the work actually performed. If we take the time to discuss these together then it does not seem so bad that we have never heard of the ‘UN Decade of Ecosystem Restoration’ before.

SOURCES:
RITCHIE Hannah; 2024; Not the End of the World, How We Can Be the First Generation to Build a Sustainable Planet; p. 221 – 222; Publisher Penguin Random House; UK
N.N.; About the UN Decade; URL: https://www.decadeonrestoration.org/about-un-decade ; accessed on February 22nd 2025
N.N.; UN Decade on Ecosystem Restoration; URL: https://en.wikipedia.org/wiki/UN_Decade_on_Ecosystem_Restoration ; accessed on February 22nd 2025
N.N.; 30 by 30; URL: https://en.wikipedia.org/wiki/30_by_30 ; accessed on February 22nd 2025
N.N.; Kunming-Montreal Global Biodiversity Framework; URL: https://en.wikipedia.org/wiki/Kunming-Montreal_Global_Biodiversity_Framework ; accessed on February 22nd 2025
N.N.; Just 2.8% of the World’s Ocean is protected “Effectively”; URL: https://www.bloomberg.org/press/just-2-8-of-the-worlds-ocean-is-protected-effectively ; accessed on February 22nd 2025
N.N.; COP15: Nations adopt four goals, 23 targets for 2030 in landmark UN biodiversity agreement – Official CBD Press Release – 19 December 2022, Montreal; URL: https://www.cbd.int/article/cop15-cbd-press-release-final-19dec2022 ; accessed on February 23rd 2025
N.N.; World must act faster to protect 30% of the planet by 2030; URL: https://www.unep.org/news-and-stories/press-release/world-must-act-faster-protect-30-planet-2030 ; accessed on February 23rd 2025
N.N.; Nature needs half; URL: https://natureneedshalf.org/ ; accessed on February 22nd 2025
DINERSTEIN E.; An Ecoregion-Based Approach to Protecting Half the Terrestrial Realm; BioScience Vol. 67 No. 6; June 2017

Following Blog 11 and Blog 12 I want to discuss a concept related to increasing biodiversity, one that makes my adventurous heart sing.
Rewilding.
What a beautiful word! Let it sink in for a moment.
Rewilding is a form of progressive nature conservation. The rules are simple and as follows.
Nature leads. As people we do not define a desired end state for an area. Nature evolves in the direction it chooses and this evolution is a continuous process. We do not expect a return to the past, nature adapts to the form that suits the current circumstances best and this in the most resilient way to withstand the future environmental conditions.
Simultaneously, we interact minimally. Nature is capable of managing itself – and does an excellent job at it. The exception to this ‘hands-off-rule’ is the reversing of past human influences that have left marks on the environment. Examples are the removal of dams that no longer serve a purpose so rivers can flow (and spill) freely and the reintroduction of apex predators so they can, as natures engineers, rule once again over the targeted area.
The Yellowstone Wolf Project of Blog 12 is a successful example of Rewilding on land. The Cabo Pulmo project from Blog 4, where the underwater world revived, is an example of successful Rewilding under water.
These are American projects, but initiatives are ongoing all over the world. ‘Rewilding Europe’ is for instance an inspiring organization that oversees, in collaboration with numerous partners, 10 impressive nature areas spread across the European continent. A handful of the actions they are focusing on are the reintroduction of natural grazers in Spain who facilitate the regeneration of healthy forest (Iberian Highlands), the removal of dams in Sweden so salmon can migrate more easily (Swedish Lapland) and the return of the bison in Romania so this species, previously extinct in this area, can again support the food chain (Southern Carpatians). Their most important action remains the inaction: keep the areas free from human influences so nature can take the reins.
When Rewilding is done correctly we know that nature can recover – often incredibly fast and seemingly miraculously. Biodiversity flourishes again and the planet provides us, in direct and indirect way, of the services – clean water, clean air, climate regulation, carbon dioxide absorption, protection against floods,… – that we have been taken for granted for the last couple of centuries.
In the next blog I shine a light on how much land and sea area we ideally leave to nature’s lead to restore the equilibrium between us as the human species and our environment. I will also explain how we are intending to reach this feasible goal. Because we can absolutely succeed at this balancing act!

SOURCES:
BUTFIELD Colin & HUGHES Jonnie (auteurs), Z.K.H. Prins William (voorwoord); 2021; Earthshot – Hoe we onze planeet kunnen redden; p. 103 – 121; Uitgeverij Luitingh-Sijthoff; Amsterdam
RITCHIE Hannah; 2024; Not the End of the World, How We Can Be the First Generation to Build a Sustainable Planet; p. 220 – 222; Publisher Penguin Random House; UK
N.N.; Rewilding; URL: https://en.wikipedia.org/wiki/Rewilding ; accessed February 9th 2025
N.N.; Rewilding Europe; URL: https://rewildingeurope.com/ ; accessed February 9th 2025

Blog 13 - Rewilding

Following Blog 11 and Blog 12 I want to discuss a concept related to increasing biodiversity, one that makes my adventurous heart sing.
Rewilding.
What a beautiful word! Let it sink in for a moment.

Rewilding is a form of progressive nature conservation. The rules are simple and as follows.
Nature leads. As people we do not define a desired end state for an area. Nature evolves in the direction it chooses and this evolution is a continuous process. We do not expect a return to the past, nature adapts to the form that suits the current circumstances best and this in the most resilient way to withstand the future environmental conditions.
Simultaneously, we interact minimally. Nature is capable of managing itself – and does an excellent job at it. The exception to this ‘hands-off-rule’ is the reversing of past human influences that have left marks on the environment. Examples are the removal of dams that no longer serve a purpose so rivers can flow (and spill) freely and the reintroduction of apex predators so they can, as natures engineers, rule once again over the targeted area.

The Yellowstone Wolf Project of Blog 12 is a successful example of Rewilding on land. The Cabo Pulmo project from Blog 4, where the underwater world revived, is an example of successful Rewilding under water.
These are American projects, but initiatives are ongoing all over the world. ‘Rewilding Europe’ is for instance an inspiring organization that oversees, in collaboration with numerous partners, 10 impressive nature areas spread across the European continent. A handful of the actions they are focusing on are the reintroduction of natural grazers in Spain who facilitate the regeneration of healthy forest (Iberian Highlands), the removal of dams in Sweden so salmon can migrate more easily (Swedish Lapland) and the return of the bison in Romania so this species, previously extinct in this area, can again support the food chain (Southern Carpatians). Their most important action remains the inaction: keep the areas free from human influences so nature can take the reins.

When Rewilding is done correctly we know that nature can recover – often incredibly fast and seemingly miraculously. Biodiversity flourishes again and the planet provides us, in direct and indirect way, of the services – clean water, clean air, climate regulation, carbon dioxide absorption, protection against floods,… – that we have been taken for granted for the last couple of centuries.

In the next blog I shine a light on how much land and sea area we ideally leave to nature’s lead to restore the equilibrium between us as the human species and our environment. I will also explain how we are intending to reach this feasible goal. Because we can absolutely succeed at this balancing act!

SOURCES:
BUTFIELD Colin & HUGHES Jonnie (auteurs), Z.K.H. Prins William (voorwoord); 2021; Earthshot – Hoe we onze planeet kunnen redden; p. 103 – 121; Uitgeverij Luitingh-Sijthoff; Amsterdam
RITCHIE Hannah; 2024; Not the End of the World, How We Can Be the First Generation to Build a Sustainable Planet; p. 220 – 222; Publisher Penguin Random House; UK
N.N.; Rewilding; URL: https://en.wikipedia.org/wiki/Rewilding ; accessed February 9th 2025
N.N.; Rewilding Europe; URL: https://rewildingeurope.com/ ; accessed February 9th 2025

For the third Earthshot, ‘Protecting and restoring nature’, I start with a blog on biodiversity. A hot topic that calls for our well-deserved attention.
Biodiversity handles the variation of life on earth. It encompasses the diversity of species, genes and ecosystems. We thus not merely count the amount of different bacteria, fungi, plants and animals, but also study their gene pools, the size of the populations, how they relate to other species and their ecosystems. A straightforward definition does not exist, the concept is as multifaceted and complex as the studied combination of biological systems and interactions.
Healthy biodiversity guarantees that nature provides us with many vital functions. This is amongst others about food security (the right microbiology of the soil so crops thrive and the pollination of plants by pollinators), purity of the air we breath and the water we drink, development of medication, protection against natural disasters and the resilience of the ecosystems to recover after the occurrence of such a disaster.
So it is, independent of the intrinsic value and right to exist of the species we share this earth with, of importance to the conservation of the human species that biodiversity is valued and maintained in good condition.
This leads to a first moment of perspective: we are as people 1 out of the 8.7 million species existing on this planet. We are thus – and luckily so – not alone.
It is natural that species go extinct. Standard evolutionary circumstances lead to mother earth losing 10% of her species every one million years. Simultaneously new ones arise. Organisms evolve and optimize themselves in relation to their ever-changing environment. This regenerative process moves along at a steady and calm pace which assures the stability of the whole network is not affected.
In the history of our planet there are five incidents during which the loss of species extremely accelerated which led to a drastic metamorphosis of the life on earth. These are the five mass-extinctions. A mass-extinction is defined as the loss of 75% of all species in the geologically short timespan of about 2 million years. Throughout the third mass-extinction, 250 million years ago, 96% of the species went extinct. During the fifth mass-extinction, 65 million years ago, the dinosaurs were part of the 76% of species that would never see the light of day again. Every one of these 5 mass-extinctions was initiated by big geological or climatological changes.
This requires a second moment of perspective: the first homo sapiens appeared 300 000 years ago. As human species we thus have never had to try to survive a mass-extinction.
That is to say…
The rate at which species are disappearing nowadays is a 100 to 1000 times faster than the evolutionary normal rate of species change. Calculations estimate that 1% of the species have gone extinct between 1500 and now. If we keep up with this wipe-out rate, we will complete a mass-extinction within 37 500 years: 75% of the species will have gone extinct by then. It would mean that you and me, at this very moment, are in the midst of the sixth mass-extinction.
Third moment of perspective: statistically the chances would be big that the humas species would be amongst the species not to survive this.
Bummer.
Even though this all sounds terribly alarming (and – let’s be honest – it is), this mass-extinction has not yet come to completion. We are not even close to a 75% loss of species. If we swiftly (in a humanly short timespan) assure the rate of species extinction drops again to its natural average, this disaster can be deflected. It is a plausible scenario that this extreme extinction wave of the past let’s say 500 years becomes, on a geological timeframe, eventually totally insignificant. We have a handle on this. Compared to the past 5 mass-extinctions the origin of the now occurring species loss is not geological or climatological. There is no comet that needs to change course or no volcano we need to kindly request not to erupt. We are sitting at the control panel. It is about consciously choosing another program.
Because the current program is exterminating our co-earthlings.
Simplified there are in this day and age two main reasons for species to go extinct. Either a species is being hunted/fished/cut/harvested at such a rate that prohibits natural and durable regeneration which then finally leads to extinction. This is the fate that mostly befalls (big) mammals. Or the surroundings of a species change too quickly too drastically which results in insufficient time for the species to evolve to live in its altered environment. This is the fate that we are driving a huge amount of all types of species to as a consequence of climate change or by physically removing or fragmenting their habitat.
Well, the uncontrolled hunting and overfishing, the accelerated climate change, the disappearing and fragmenting of habitats, that is all, in the current circumstances, on us. We are putting too much pressure on the other 8 699 999 species that are so kindly offering us the advantages linked to a healthy biodiversity. Luckily the solution to this problem is in its origin and also within our ‘circle of control’. This realization is growing and in the meantime there are committed groups and individuals that have initiated change. Action is the password that will set the new and improved program in motion.
The next blog will handle one of the success stories that proofs it is absolutely possible to turn the tide.
After these hard truths, we are up for that.

SOURCES:
RITCHIE Hannah; 2024; Not the End of the World, How We Can Be the First Generation to Build a Sustainable Planet; p. 193 – 222; Publisher Penguin Random House; UK
BUTFIELD Colin & HUGHES Jonnie (authors), Z.K.H. Prins William (foreword); 2021; Eartshot – How to save our planet; Publisher John Murray; London
N.N.; Homo Sapiens; URL: https://humanorigins.si.edu/evidence/human-fossils/species/homo-sapiens ; accessed on January 27th 2025
N.N.; Recorded species extinctions since 1500; URL: https://ourworldindata.org/grapher/extinct-species-since-1500?tab=table ; accessed on January 27th 2025
LINDWALL Courtney; Biodiversity 101 – How do we define and measure biodiversity-and just why is it so important?; URL: https://www.nrdc.org/stories/biodiversity-101 ; accessed on January 27th 2025
N.N.; What is biodiversity and why is it important?; URL: https://www.clientearth.org/latest/news/what-is-biodiversity-and-why-is-it-important/ ; accessed on January 27th 2025
N.N.; What is biodiversity and why is it important?; URL: https://www.greenpeace.org.uk/challenges/wildlife-and-biodiversity/what-is-biodiversity/ ; accessed on January 27th 2025
SHAW Julie; Why is biodiversity important?; URL: https://www.conservation.org/blog/why-is-biodiversity-important ; accessed on January 27th 2025
BEGUM Tammana; What is mass extinction and are we facing a sixth one? URL: https://www.nhm.ac.uk/discover/what-is-mass-extinction-and-are-we-facing-a-sixth-one.html ; accessed on January 27th 2025

Blog 11 - Biodiversity and the loss of it

For the third Earthshot, ‘Protecting and restoring nature’, I start with a blog on biodiversity. A hot topic that calls for our well-deserved attention.

Biodiversity handles the variation of life on earth. It encompasses the diversity of species, genes and ecosystems. We thus not merely count the amount of different bacteria, fungi, plants and animals, but also study their gene pools, the size of the populations, how they relate to other species and their ecosystems. A straightforward definition does not exist, the concept is as multifaceted and complex as the studied combination of biological systems and interactions.

Healthy biodiversity guarantees that nature provides us with many vital functions. This is amongst others about food security (the right microbiology of the soil so crops thrive and the pollination of plants by pollinators), purity of the air we breath and the water we drink, development of medication, protection against natural disasters and the resilience of the ecosystems to recover after the occurrence of such a disaster.

So it is, independent of the intrinsic value and right to exist of the species we share this earth with, of importance to the conservation of the human species that biodiversity is valued and maintained in good condition.

This leads to a first moment of perspective: we are as people 1 out of the 8.7 million species existing on this planet. We are thus – and luckily so – not alone.

It is natural that species go extinct. Standard evolutionary circumstances lead to mother earth losing 10% of her species every one million years. Simultaneously new ones arise. Organisms evolve and optimize themselves in relation to their ever-changing environment. This regenerative process moves along at a steady and calm pace which assures the stability of the whole network is not affected.

In the history of our planet there are five incidents during which the loss of species extremely accelerated which led to a drastic metamorphosis of the life on earth. These are the five mass-extinctions. A mass-extinction is defined as the loss of 75% of all species in the geologically short timespan of about 2 million years. Throughout the third mass-extinction, 250 million years ago, 96% of the species went extinct. During the fifth mass-extinction, 65 million years ago, the dinosaurs were part of the 76% of species that would never see the light of day again. Every one of these 5 mass-extinctions was initiated by big geological or climatological changes.

This requires a second moment of perspective: the first homo sapiens appeared 300 000 years ago. As human species we thus have never had to try to survive a mass-extinction.

That is to say…

The rate at which species are disappearing nowadays is a 100 to 1000 times faster than the evolutionary normal rate of species change. Calculations estimate that 1% of the species have gone extinct between 1500 and now. If we keep up with this wipe-out rate, we will complete a mass-extinction within 37 500 years: 75% of the species will have gone extinct by then. It would mean that you and me, at this very moment, are in the midst of the sixth mass-extinction.

Third moment of perspective: statistically the chances would be big that the humas species would be amongst the species not to survive this.

Bummer.

Even though this all sounds terribly alarming (and – let’s be honest – it is), this mass-extinction has not yet come to completion. We are not even close to a 75% loss of species. If we swiftly (in a humanly short timespan) assure the rate of species extinction drops again to its natural average, this disaster can be deflected. It is a plausible scenario that this extreme extinction wave of the past let’s say 500 years becomes, on a geological timeframe, eventually totally insignificant. We have a handle on this. Compared to the past 5 mass-extinctions the origin of the now occurring species loss is not geological or climatological. There is no comet that needs to change course or no volcano we need to kindly request not to erupt. We are sitting at the control panel. It is about consciously choosing another program.

Because the current program is exterminating our co-earthlings.

Simplified there are in this day and age two main reasons for species to go extinct. Either a species is being hunted/fished/cut/harvested at such a rate that prohibits natural and durable regeneration which then finally leads to extinction. This is the fate that mostly befalls (big) mammals. Or the surroundings of a species change too quickly too drastically which results in insufficient time for the species to evolve to live in its altered environment. This is the fate that we are driving a huge amount of all types of species to as a consequence of climate change or by physically removing or fragmenting their habitat.

Well, the uncontrolled hunting and overfishing, the accelerated climate change, the disappearing and fragmenting of habitats, that is all, in the current circumstances, on us. We are putting too much pressure on the other 8 699 999 species that are so kindly offering us the advantages linked to a healthy biodiversity. Luckily the solution to this problem is in its origin and also within our ‘circle of control’. This realization is growing and in the meantime there are committed groups and individuals that have initiated change. Action is the password that will set the new and improved program in motion.

The next blog will handle one of the success stories that proofs it is absolutely possible to turn the tide.
After these hard truths, we are up for that.

SOURCES:
RITCHIE Hannah; 2024; Not the End of the World, How We Can Be the First Generation to Build a Sustainable Planet; p. 193 – 222; Publisher Penguin Random House; UK
BUTFIELD Colin & HUGHES Jonnie (authors), Z.K.H. Prins William (foreword); 2021; Eartshot – How to save our planet; Publisher John Murray; London
N.N.; Homo Sapiens; URL: https://humanorigins.si.edu/evidence/human-fossils/species/homo-sapiens ; accessed on January 27th 2025
N.N.; Recorded species extinctions since 1500; URL: https://ourworldindata.org/grapher/extinct-species-since-1500?tab=table ; accessed on January 27th 2025
LINDWALL Courtney; Biodiversity 101 – How do we define and measure biodiversity-and just why is it so important?; URL: https://www.nrdc.org/stories/biodiversity-101 ; accessed on January 27th 2025
N.N.; What is biodiversity and why is it important?; URL: https://www.clientearth.org/latest/news/what-is-biodiversity-and-why-is-it-important/ ; accessed on January 27th 2025
N.N.; What is biodiversity and why is it important?; URL: https://www.greenpeace.org.uk/challenges/wildlife-and-biodiversity/what-is-biodiversity/ ; accessed on January 27th 2025
SHAW Julie; Why is biodiversity important?; URL: https://www.conservation.org/blog/why-is-biodiversity-important ; accessed on January 27th 2025
BEGUM Tammana; What is mass extinction and are we facing a sixth one? URL: https://www.nhm.ac.uk/discover/what-is-mass-extinction-and-are-we-facing-a-sixth-one.html ; accessed on January 27th 2025

In blog 8 I wrote how, thanks to the ozone-oxygen equilibrated cycle, all UV-C radiation and almost all UV-B radiation are absorbed by oxygen (O2) and ozone (O3) in the ozone layer. We are grateful this radiation does not reach the earth because this reduces the amount of severe sunburns and skin cancers. However, initially ignorantly, we humas have succeeded to disrupt the equilibrium resulting in lowered ozone concentrations in the ozone layer. I explain in this blog how this happened. How we managed, after realizing our mistake, to turn the tide and prevent further destructive consequences – the good part of this story – is for blog 10.
In the 1930s manufacturers started using halons in common household products. This was revolutionary at the time. Halons are hydrocarbons (compounds built with carbon atoms (C) and hydrogen atoms (H)) in which some of the hydrogen atoms are replaced by halogens such as fluorine (F), chlorine (Cl), bromine (Br) or iodine (I). These chemical compounds have excellent characteristics to be used as refrigerant in refrigerators and air conditioners and were also added to spray cans and fire extinguishers as aerosol. They are not toxic which made them logically way more attractive than the toxic substances that were previously used for the same applications. Well-known examples of halons are CFC’s, chlorofluorocarbons.
If the refrigerator is end of life and the halons end up in the air, they can remain unaltered in the troposphere for 45 – 150 years. When researcher James Lovelock demonstrated with his measurements that halons were present everywhere in the troposphere, this was initially not considered an issue. Because of their chemical stability halons are inert and consequently non-harmful in the troposphere.
Sherry Rowland and Mario Molina executed more extensive research and stumbled upon a – literally – more elevated problem. Also because of their stability, halons have time to migrate into the stratosphere. This is in contrast to most other substances that are emitted by people near the earth’s surface. They naturally decompose in the troposphere. Once arrived in the stratosphere, the halons are exposed to energetic forces they did not have to deal with in the troposphere: UV-C radiation. This intense radiation succeeds in breaking the chemical bond between the halogen atom (chlorine in case of CFC’s) and the other part of the molecule resulting in the formation of a halogen radical (Cl. in case of CFC’s). This radical is very reactive and reacts with pleasure and ease with the chemical instable O3 in the ozone layer.
I explain, based on two chemical formulas, what happens exactly. The example handles a chlorine radical (Cl.) that has originated from destruction of a CFC molecule in the stratosphere. The reactions are identical for any other halogen radicals such as for instance the bromine radical (Br.).
Follow along.
Reaction (1)
While the ozone molecule is split in the natural ozone-oxygen cycle by UV-C or UV-B radiation (reaction (3) of blog 8), reaction with a chlorine radical (Cl.) will also lead to dissociation. It generates a chlorine monoxide radical (ClO.) and an oxygen molecule (O2). There is no absorption of UV radiation occurring.
Cl. + O3 —> ClO. + O2
We have now one destroyed O3 molecule.
Help! This was not supposed to happen!
Reaction (2)
Even more alarming than the occurrence of reaction (1) is the fact that the formed ClO. is also highly reactive. It can react with an oxygen radical (O.) present in the stratosphere. This leads to the reappearance of the chlorine radical (Cl.), that had been consumed in reaction (1).
ClO. + O. —> Cl. + O2
The now again free Cl. can destroy another O3 molecule via reaction (1).
Now we are in real trouble!
This means that the chlorine radical acts as a catalyst. A chain reaction has been initiated in which the Cl. itself is not being consumed, it simply facilitates the destruction of O3. In this way a single chlorine radical can be responsible for the removal of up to 100 000 O3 molecules. Eventually this mechanism leads to significant reduction of the O3 concentration in the ozone layer.
That was really not supposed to happen…
That this chemistry and the associated effect was actually going on in our stratosphere was illustrated – painfully – in the 1980s when images of ‘the hole’ in the ozone layer above Antarctica were published. (It was at the same time an example of excellent science imaging and communication.) The word ‘hole’ is a hyperbole, I assume brought to life to highlight the severeness of the problem.
There is no actual hole…
What would that even mean?
An area of vacuum in the atmosphere?
As explained in blog 8 the ozone layer is simply air. The density of the gas molecules does not alter there where we define the presence of the ‘hole’. What is different in the area of the ‘hole’ though is the concentration of the ozone molecules. In 1994 we measured the lowest ozone concentration ever. It was measured above Antarctica and equaled 73 DU (Dobson Unit, measuring unit for ozone). The concentration of ozone in that year at that spot was more than 60% lower than what had been, under normal circumstances (without halons in the air), the minimal value ever measured, which is 220 DU. It is this base value that determines the definition of the ‘hole’: there where the ozone concentration is lower than the historical healthy minimum of ozone (220 DU), we talk about a ‘hole’ in the ozone layer.
While the concentration of ozone in the stratosphere has lowered almost everywhere due to the presence of halons, this ‘hole’ forms yearly above Antarctica at the end of winter (September/October). That the lowest concentrations of O3 are measured above the south pole was initially contra intuitive. Naturally the concentration of O3 is namely lowest above the equator and highest above the poles. Furthermore, our most southern continent is not exactly densely populated so there are very little – I hope none – old air conditioners being dumped from which CFC molecules can leak into the atmosphere.
Further research explained this phenomenon. At low temperature polar stratospheric clouds (PSCs) form above the south pole. These clouds attract halons electrostatically which then leads to a higher concentration of this destructive compound above Antarctica, compared to other areas in the stratosphere. Consequently, more halogen radicals are formed in this area which are then available to catalytically destroy a higher fraction of the O3 molecules in the ozone layer. The lower temperature in the stratosphere above Antarctica at the end of the winter season is also a driver for the occurrence of the reactions discussed above.
There you go, a classic example of a global problem: pollution generated at one spot on planet earth results in negative effects all over the world and most severely even at a totally different location.
This all sounds pretty depressing, doesn’t it?
Well, it was.
We have however, collectively and constructively, reacted to this problem. Because of that we can now breath a sigh of relief and cherish realistic hope for a complete recovery of the ozone layer in the near future. How we have managed to do this and why there is a link to the Canadian city of Montreal, I will explain in blog 10 where the story continues.

SOURCES:
N.N.; World of Change: Antarctic Ozone hole; URL: https://earthobservatory.nasa.gov/world-of-change/Ozone; accessed at January 14th 2025
N.N.; Q9 What are the chlorine and bromine reactions that destroy stratospheric ozone?; URL: https://csl.noaa.gov/assessments/ozone/2010/twentyquestions/Q9.pdf ; accessed at January 14th 2025
N.N.; Q10 Why has an “ozone hole” appeared over Antarctica when ozone-depleting substances are present throughout the stratosphere?; URL : https://csl.noaa.gov/assessments/ozone/2010/twentyquestions/Q10.pdf ; accessed at January 14th 2025
N.N.; Dobson unit; URL : https://en.wikipedia.org/wiki/Dobson_unit ; accessed at January 14th 2025
N.N.; Ozone depletion; URL: https://en.wikipedia.org/wiki/Ozone_depletion ; accessed at January 14th 2025
N.N.; Satellites track the health of the ozone layer; URL: https://earth.esa.int/eogateway/news/satellites-track-the-health-of-the-ozone-layer ; accessed at January 14th 2025
N.N.; Main Ozone hole poster ; URL : https://www.nasa.gov/wp-content/uploads/2013/05/752034main_ozone_hole_poster.pdf ; accessed at January 14th 2025
N.N.; Ozone Depletion and Climate Change; URL: https://uk-air.defra.gov.uk/research/ozone-uv/moreinfo?view=deleption-climate-change ; accessed at January 14th 2025
N.N.; Clorine monoxide; URL: https://en.wikipedia.org/wiki/Chlorine_monoxide ; accessed at January 14th 2025
CLARK Jim; Chemguide: Core Chemistry 14 – 16, Environmental problems involving the air – ozone depletion in the high atmosphere; URL: https://www.chemguide.uk/14to16/air/ozone.html ; accessed at January 14th 2025
N.N.; Chlorofluorocarbon; URL: https://en.wikipedia.org/wiki/Chlorofluorocarbon ; accessed at January 14th 2025
N.N.; Halogeen; URL: https://nl.wikipedia.org/wiki/Halogeen ; accessed at January 14th 2025
N.N.; Halon; URL: https://nl.wikipedia.org/wiki/Halon ; accessed at January 14th 2025
American Chemical Society; Chloroflorocarbons and Ozone Depletion; URL: https://nl.wikipedia.org/wiki/Halon ; accessed at January 14th 2025

Blog 9 - How about that hole?

In blog 8 I wrote how, thanks to the ozone-oxygen equilibrated cycle, all UV-C radiation and almost all UV-B radiation are absorbed by oxygen (O2) and ozone (O3) in the ozone layer. We are grateful this radiation does not reach the earth because this reduces the amount of severe sunburns and skin cancers. However, initially ignorantly, we humas have succeeded to disrupt the equilibrium resulting in lowered ozone concentrations in the ozone layer. I explain in this blog how this happened. How we managed, after realizing our mistake, to turn the tide and prevent further destructive consequences – the good part of this story – is for blog 10.

In the 1930s manufacturers started using halons in common household products. This was revolutionary at the time. Halons are hydrocarbons (compounds built with carbon atoms (C) and hydrogen atoms (H)) in which some of the hydrogen atoms are replaced by halogens such as fluorine (F), chlorine (Cl), bromine (Br) or iodine (I). These chemical compounds have excellent characteristics to be used as refrigerant in refrigerators and air conditioners and were also added to spray cans and fire extinguishers as aerosol. They are not toxic which made them logically way more attractive than the toxic substances that were previously used for the same applications. Well-known examples of halons are CFC’s, chlorofluorocarbons.

If the refrigerator is end of life and the halons end up in the air, they can remain unaltered in the troposphere for 45 – 150 years. When researcher James Lovelock demonstrated with his measurements that halons were present everywhere in the troposphere, this was initially not considered an issue. Because of their chemical stability halons are inert and consequently non-harmful in the troposphere.

Sherry Rowland and Mario Molina executed more extensive research and stumbled upon a – literally – more elevated problem. Also because of their stability, halons have time to migrate into the stratosphere. This is in contrast to most other substances that are emitted by people near the earth’s surface. They naturally decompose in the troposphere. Once arrived in the stratosphere, the halons are exposed to energetic forces they did not have to deal with in the troposphere: UV-C radiation. This intense radiation succeeds in breaking the chemical bond between the halogen atom (chlorine in case of CFC’s) and the other part of the molecule resulting in the formation of a halogen radical (Cl. in case of CFC’s). This radical is very reactive and reacts with pleasure and ease with the chemical instable O3 in the ozone layer.

I explain, based on two chemical formulas, what happens exactly. The example handles a chlorine radical (Cl.) that has originated from destruction of a CFC molecule in the stratosphere. The reactions are identical for any other halogen radicals such as for instance the bromine radical (Br.).
Follow along.

Reaction (1)

While the ozone molecule is split in the natural ozone-oxygen cycle by UV-C or UV-B radiation (reaction (3) of blog 8), reaction with a chlorine radical (Cl.) will also lead to dissociation. It generates a chlorine monoxide radical (ClO.) and an oxygen molecule (O2). There is no absorption of UV radiation occurring.

Cl. + O3 —> ClO. + O2

We have now one destroyed O3 molecule.
Help! This was not supposed to happen!

Reaction (2)

Even more alarming than the occurrence of reaction (1) is the fact that the formed ClO. is also highly reactive. It can react with an oxygen radical (O.) present in the stratosphere. This leads to the reappearance of the chlorine radical (Cl.), that had been consumed in reaction (1).

ClO. + O. —> Cl. + O2

The now again free Cl. can destroy another O3 molecule via reaction (1).
Now we are in real trouble!

This means that the chlorine radical acts as a catalyst. A chain reaction has been initiated in which the Cl. itself is not being consumed, it simply facilitates the destruction of O3. In this way a single chlorine radical can be responsible for the removal of up to 100 000 O3 molecules. Eventually this mechanism leads to significant reduction of the O3 concentration in the ozone layer.

That was really not supposed to happen…

That this chemistry and the associated effect was actually going on in our stratosphere was illustrated – painfully – in the 1980s when images of ‘the hole’ in the ozone layer above Antarctica were published. (It was at the same time an example of excellent science imaging and communication.) The word ‘hole’ is a hyperbole, I assume brought to life to highlight the severeness of the problem.

There is no actual hole…
What would that even mean?
An area of vacuum in the atmosphere?

As explained in blog 8 the ozone layer is simply air. The density of the gas molecules does not alter there where we define the presence of the ‘hole’. What is different in the area of the ‘hole’ though is the concentration of the ozone molecules. In 1994 we measured the lowest ozone concentration ever. It was measured above Antarctica and equaled 73 DU (Dobson Unit, measuring unit for ozone). The concentration of ozone in that year at that spot was more than 60% lower than what had been, under normal circumstances (without halons in the air), the minimal value ever measured, which is 220 DU. It is this base value that determines the definition of the ‘hole’: there where the ozone concentration is lower than the historical healthy minimum of ozone (220 DU), we talk about a ‘hole’ in the ozone layer.

While the concentration of ozone in the stratosphere has lowered almost everywhere due to the presence of halons, this ‘hole’ forms yearly above Antarctica at the end of winter (September/October). That the lowest concentrations of O3 are measured above the south pole was initially contra intuitive. Naturally the concentration of O3 is namely lowest above the equator and highest above the poles. Furthermore, our most southern continent is not exactly densely populated so there are very little – I hope none – old air conditioners being dumped from which CFC molecules can leak into the atmosphere.
Further research explained this phenomenon. At low temperature polar stratospheric clouds (PSCs) form above the south pole. These clouds attract halons electrostatically which then leads to a higher concentration of this destructive compound above Antarctica, compared to other areas in the stratosphere. Consequently, more halogen radicals are formed in this area which are then available to catalytically destroy a higher fraction of the O3 molecules in the ozone layer. The lower temperature in the stratosphere above Antarctica at the end of the winter season is also a driver for the occurrence of the reactions discussed above.
There you go, a classic example of a global problem: pollution generated at one spot on planet earth results in negative effects all over the world and most severely even at a totally different location.

This all sounds pretty depressing, doesn’t it?
Well, it was.
We have however, collectively and constructively, reacted to this problem. Because of that we can now breath a sigh of relief and cherish realistic hope for a complete recovery of the ozone layer in the near future. How we have managed to do this and why there is a link to the Canadian city of Montreal, I will explain in blog 10 where the story continues.

SOURCES:
N.N.; World of Change: Antarctic Ozone hole; URL: https://earthobservatory.nasa.gov/world-of-change/Ozone; accessed at January 14th 2025
N.N.; Q9 What are the chlorine and bromine reactions that destroy stratospheric ozone?; URL: https://csl.noaa.gov/assessments/ozone/2010/twentyquestions/Q9.pdf ; accessed at January 14th 2025
N.N.; Q10 Why has an “ozone hole” appeared over Antarctica when ozone-depleting substances are present throughout the stratosphere?; URL : https://csl.noaa.gov/assessments/ozone/2010/twentyquestions/Q10.pdf ; accessed at January 14th 2025
N.N.; Dobson unit; URL : https://en.wikipedia.org/wiki/Dobson_unit ; accessed at January 14th 2025
N.N.; Ozone depletion; URL: https://en.wikipedia.org/wiki/Ozone_depletion ; accessed at January 14th 2025
N.N.; Satellites track the health of the ozone layer; URL: https://earth.esa.int/eogateway/news/satellites-track-the-health-of-the-ozone-layer ; accessed at January 14th 2025
N.N.; Main Ozone hole poster ; URL : https://www.nasa.gov/wp-content/uploads/2013/05/752034main_ozone_hole_poster.pdf ; accessed at January 14th 2025
N.N.; Ozone Depletion and Climate Change; URL: https://uk-air.defra.gov.uk/research/ozone-uv/moreinfo?view=deleption-climate-change ; accessed at January 14th 2025
N.N.; Clorine monoxide; URL: https://en.wikipedia.org/wiki/Chlorine_monoxide ; accessed at January 14th 2025
CLARK Jim; Chemguide: Core Chemistry 14 – 16, Environmental problems involving the air – ozone depletion in the high atmosphere; URL: https://www.chemguide.uk/14to16/air/ozone.html ; accessed at January 14th 2025
N.N.; Chlorofluorocarbon; URL: https://en.wikipedia.org/wiki/Chlorofluorocarbon ; accessed at January 14th 2025
N.N.; Halogeen; URL: https://nl.wikipedia.org/wiki/Halogeen ; accessed at January 14th 2025
N.N.; Halon; URL: https://nl.wikipedia.org/wiki/Halon ; accessed at January 14th 2025
American Chemical Society; Chloroflorocarbons and Ozone Depletion; URL: https://nl.wikipedia.org/wiki/Halon ; accessed at January 14th 2025

One of the atmosphere’s sublayers has an important function and an interesting recent history: the ozone layer. In this blog I give its definition and explain how it protects life on earth, in the next blog the story about the hole.
The ozone layer can be found, as mentioned in blog 7, between 15 and 30 km above sea level. This layer contains … drum roll please … simply air. The general composition of gases in the ozone layer is the same as the air we breathe at the earth’s surface: 70% nitrogen (N2), 20.9% oxygen (O2), 0.9% argon (Ar) and 0.1% of other gasses. This might surprise you.
Where is that notorious ozone (O3)?
The average concentration of ozone in the atmosphere is 0.3 ppm. So ozone can be found within the 0.1% other gasses of the air composition. The same is true for the ozone in the ozone layer, but the concentration of ozone here is a bit higher. It varies between 2 and 15 ppm. Not particularly high, you might think. That’s right, looking at it as an absolute value, the concentration is still very low: maximally 15 out of 1 million gas molecules in the ozone layer are ozone molecules. The fact that this layer is still named after this component is mostly signaling its importance for life on this planet.
The ozone layer protects us, as a natural and transparent sunscreen, against UV radiation from the sun. The fraction of the solar radiation spectrum we know best is the radiation with wavelengths between 380 nm (color violet) and 700 nm (color red). We observe this as visible light. Radiation with a shorter wavelength than visible light (smaller than 380 nm) is called ultraviolet (UV) light. This UV light is further partitioned into three sub spectra: UV-C (100 – 280 nm), UV-B (280 – 315 nm) and UV-A (315 – 400 nm). The shorter the wavelength, the more intense the radiation.
For humans, too long exposure to UV light leads on short term to burned skin. In the long run too long and frequent exposure increases the risk of skin cancer. This is well-known. It is the reason why we collectively apply sunscreen when lying on our towel staring at the blue sky on a beach in the south of France.
It might be lesser known that oxygen and ozone in the stratosphere have already executed the most important part of the protective work before the UV rays reach the surface of the earth.
To explain how exactly oxygen and ozone save our delicate skin, I briefly dive into the chemistry. The active mechanism is called the Chapman cycle. It exists of four main reactions.
Follow along.
Reaction (1): oxygen-photodissociation
In the stratosphere oxygen will be split into two oxygen radicals (O.) by UV-C radiation with wavelength shorter than 242 nm.
O2 + hv(< 242 nm) —> 2 O.
This reaction is called ‘oxygen-photodissociation’ and considering the high concentration of oxygen in the stratosphere (the radiation easily ‘finds’ an oxygen molecule to split), all UV-C radiation with wavelength shorter than 242 nm is absorbed in the stratosphere. By oxygen.
Reaction (2): formation of ozone
The oxygen radicals formed in reaction (1) are highly reactive and can react with another oxygen molecule. This leads to the formation of ozone.
O2 + O. —> O3
Reaction (3): ozone-photodissociation
The formed ozone from reaction (2) is however chemically instable and will be again destroyed when absorbing UV radiation with a wavelength between 240 and 310 nm.
O3 + hv(240 – 310 nm) —> O2 + O.
This reaction is called ‘ozone-photodissociation’ and guarantees that the other fraction of UV-C radiation and more than 95% of the UV-B radiation is absorbed in the ozone layer. By ozone.
Simultaneously an oxygen radical has again originated, which can lead to formation of ozone via reaction (2). Reaction (2) and (3) alternate.
Reaction (4): loss of ozone
While reaction (1) feeds the system with additional oxygen radicals, reaction (4) removes ozone from the system. This happens when ozone reacts with an oxygen radical.
O3 + O. —> 2 O2
The formed oxygen molecules could be again split via the ‘oxygen-photodissociation’ in reaction (1).
The cycle restarts.
If this natural blockage of UV-C and UV-B radiation would not exist, I would strongly advise you to stay in your hotel room reading a good book when the sun is shining on that beautiful July afternoon. To this day there is no sunscreen available on the market that can save you in that case.
UV-A is persistent in getting through the atmosphere, we have to endure it at full blast. Even though this is the least intense variant of the UV radiation, applying sunscreen stays of utmost importance to limit the chances of premature skin aging and skin cancer.
Because of the ozone-oxygen cycle – the continuous formation and destruction of both molecules in the stratosphere during which UV radiation is being absorbed – there is a more or less constant ozone concentration present in the ozone layer. This assures that the layer can offer us lasting protection against harmful UV radiation.
What a beautiful example of nature’s ingenuity. It leads to a simple recommendation: let’s not disrupt this process. 😉

Blog 8 - The wonders of the ozone layer

One of the atmosphere’s sublayers has an important function and an interesting recent history: the ozone layer. In this blog I give its definition and explain how it protects life on earth, in the next blog the story about the hole.

The ozone layer can be found, as mentioned in blog 7, between 15 and 30 km above sea level. This layer contains … drum roll please … simply air. The general composition of gases in the ozone layer is the same as the air we breathe at the earth’s surface: 70% nitrogen (N2), 20.9% oxygen (O2), 0.9% argon (Ar) and 0.1% of other gasses. This might surprise you.

Where is that notorious ozone (O3)?

The average concentration of ozone in the atmosphere is 0.3 ppm. So ozone can be found within the 0.1% other gasses of the air composition. The same is true for the ozone in the ozone layer, but the concentration of ozone here is a bit higher. It varies between 2 and 15 ppm. Not particularly high, you might think. That’s right, looking at it as an absolute value, the concentration is still very low: maximally 15 out of 1 million gas molecules in the ozone layer are ozone molecules. The fact that this layer is still named after this component is mostly signaling its importance for life on this planet.

The ozone layer protects us, as a natural and transparent sunscreen, against UV radiation from the sun. The fraction of the solar radiation spectrum we know best is the radiation with wavelengths between 380 nm (color violet) and 700 nm (color red). We observe this as visible light. Radiation with a shorter wavelength than visible light (smaller than 380 nm) is called ultraviolet (UV) light. This UV light is further partitioned into three sub spectra: UV-C (100 – 280 nm), UV-B (280 – 315 nm) and UV-A (315 – 400 nm). The shorter the wavelength, the more intense the radiation.
For humans, too long exposure to UV light leads on short term to burned skin. In the long run too long and frequent exposure increases the risk of skin cancer. This is well-known. It is the reason why we collectively apply sunscreen when lying on our towel staring at the blue sky on a beach in the south of France.

It might be lesser known that oxygen and ozone in the stratosphere have already executed the most important part of the protective work before the UV rays reach the surface of the earth.
To explain how exactly oxygen and ozone save our delicate skin, I briefly dive into the chemistry. The active mechanism is called the Chapman cycle. It exists of four main reactions.
Follow along.

Reaction (1): oxygen-photodissociation
In the stratosphere oxygen will be split into two oxygen radicals (O.) by UV-C radiation with wavelength shorter than 242 nm.

O2 + hv(< 242 nm) —> 2 O.

This reaction is called ‘oxygen-photodissociation’ and considering the high concentration of oxygen in the stratosphere (the radiation easily ‘finds’ an oxygen molecule to split), all UV-C radiation with wavelength shorter than 242 nm is absorbed in the stratosphere. By oxygen.

Reaction (2): formation of ozone
The oxygen radicals formed in reaction (1) are highly reactive and can react with another oxygen molecule. This leads to the formation of ozone.

O2 + O. —> O3

Reaction (3): ozone-photodissociation
The formed ozone from reaction (2) is however chemically instable and will be again destroyed when absorbing UV radiation with a wavelength between 240 and 310 nm.

O3 + hv(240 – 310 nm) —> O2 + O.

This reaction is called ‘ozone-photodissociation’ and guarantees that the other fraction of UV-C radiation and more than 95% of the UV-B radiation is absorbed in the ozone layer. By ozone.

Simultaneously an oxygen radical has again originated, which can lead to formation of ozone via reaction (2). Reaction (2) and (3) alternate.

Reaction (4): loss of ozone

While reaction (1) feeds the system with additional oxygen radicals, reaction (4) removes ozone from the system. This happens when ozone reacts with an oxygen radical.

O3 + O. —> 2 O2

The formed oxygen molecules could be again split via the ‘oxygen-photodissociation’ in reaction (1).
The cycle restarts.

If this natural blockage of UV-C and UV-B radiation would not exist, I would strongly advise you to stay in your hotel room reading a good book when the sun is shining on that beautiful July afternoon. To this day there is no sunscreen available on the market that can save you in that case.
UV-A is persistent in getting through the atmosphere, we have to endure it at full blast. Even though this is the least intense variant of the UV radiation, applying sunscreen stays of utmost importance to limit the chances of premature skin aging and skin cancer.

Because of the ozone-oxygen cycle – the continuous formation and destruction of both molecules in the stratosphere during which UV radiation is being absorbed – there is a more or less constant ozone concentration present in the ozone layer. This assures that the layer can offer us lasting protection against harmful UV radiation.
What a beautiful example of nature’s ingenuity. It leads to a simple recommendation: let’s not disrupt this process. 😉

It is high time for a new blog that handles a new Earthshot. Blog 3, 4, 5 and 6 were focused on ‘Reviving of our oceans’. Blog 7, 8, 9 and 10 will be dedicated to the challenge ‘Cleaning our air’. Let’s start by talking about our life’s blanket. The atmosphere.
No air, no life. Air is a gas mixture with a specific composition of different molecules: 78% nitrogen (N2), 20.9% oxygen (O2) – this is what we breathe to live, 0.9% argon (Ar) and 0.1% of other gasses. The gas molecules in our atmosphere have the composition of air.
The sole reason why the air stays in the atmosphere and does not escape to airless space (gas molecules that are not subjected to external forces take on a volume as large as possible), is gravity. This is truly amazing when you think about it. Consider object one: the earth, and consider object two: one gas molecule. These two objects exert a force on one another, they attract each other. The magnitude of this force is directly proportional to the multiplication of both objects’ masses. This means that the bigger the product of these masses (mass object 1 x mass object 2), the bigger the gravitational force. The mass of the earth (mass object 1) is obviously way bigger than the mass of one gas molecule (mass object 2) (50 orders of magnitude bigger, so add 50 zeros). It is thus evidently the mass of the earth that assures the force between the two objects is significantly strong. However, if the gas molecule would be completely weightless, the product would be equal to zero (mass object 1 x 0 = 0), there would be no attracting forces between the two objects and the gas molecule would escape to outer space.
The gravitational force is inversely proportional to the distance (squared) between the two objects. This means that the further the earth and the gas molecule are away from each other, the smaller the force is that they exert on each other. The gas molecules are thus ‘more free’ if their distance to the earth is bigger. Consequently they can move more easily away from each other. This leads to lower air density higher up: per volume unit the amount of gas molecules is smaller. This is called ‘thin’ air and it specifically means that with each breath you inhale less gas molecules of air (and thus oxygen) at the top of the Mount Everest compared to the same inhalation at the foot of this highest mountain in the world.
The atmosphere is thus wrapped as a shell around the earth, formed by gas molecules that are spread out further from each other the higher you go.
Scientists have distinguished different layers in the atmosphere. The layer we are living in is called the troposphere. It reaches up to 15 km above sea level. 75 – 80% of the total mass of gas that is present around the earth is grouped in the troposphere. This layer houses the top of the Mount Everest, flight routes of commercial airplanes and the weather. If you are no astronaut, military air force pilot or extreme adventurer (even more extreme than climbing the Mount Everest), you will not exceed the troposphere in your lifetime. That is not something to be too sorry about because from 18 km of height (Armstrong limit) you cannot survive in our atmosphere without a space suit that regulates the pressure around your body. Search for more details on this topic if you are intrigued – it is all about the boiling of our bodily fluids, true horror.
After the troposphere the stratosphere begins. This layer ends 50 km above sea level. The American Alan Eustace was crazy enough to jump from a balloon hanging in this layer (41.4 km above the earth). There you go, seemingly my definition of an extreme adventurer. Because he choose this height, Alan moved during his free fall back to the face of the earth – thank you gravity – through the ozone layer. This sublayer of the atmosphere is a part of the stratosphere and is defined between 15 and 30 km above sea level. In blog 8 I will explain what is so fascinating about the ozone layer.
The next layer of the atmosphere is called the mesosphere and reaches from 50 up to 85 km above earth’s surface. Thanks to this layer – the density of the gas molecules is just high enough here – most meteors do not come closer than the distance of 50 km to the earth - which to me still sounds freakishly close. They will burn because of the friction that arises between the falling rock and the gas molecules present that are being pushed aside with brute force by the meteor. If you witness this protecting function of the atmosphere, you can make a wish.
After the mesosphere there is the thermosphere which ends at 600 km (some sources report 600 km) above the earth. All gas molecules in this sphere belong to the earth and are thus part of the physical atmosphere. However, a theoretical end of the atmosphere is defined withín the thermosphere, more specifically at 100 km above sea level. This boundary is called the Karman line. The distance is arbitrary chosen and 99.99997% of the total mass of gas molecules that are grouped around the earth, are present below this line. The International Space Station (ISS) is thus, theoretically speaking, located outside of our atmosphere, in outer space. However, at its altitude of 400 km the astronauts will see from time to time a somwhat lost gas molecule pass by. Don’t be fooled though, it belongs to the earth and will most probably never escape its attractional force.
To finalize, let’s add some perspective. The diameter of the earth is 6378 km. The (theoretical) atmosphere rises up to 100 km above the earth’s surface. On a smaller scale you can compare this ratio with a tennis ball and the point of a sharpened pencil. In comparison with the diameter of the earth the atmosphere is thus only a thin shell that wraps around our planet. And it is this layer of gas molecules that sustains life on earth as we know it. In the book Earthshot, astronaut Naoko Yamazaki describes how she, when looking from the right angle with the right light, is able to observe from space our atmosphere, the air we breathe. She continues by comparing the quality of our atmosphere’s air with the quality of the air in a space ship. For the astronauts it is of vital importance that this limited amount of air remains in perfect condition. The ship is floating through vacuum, there are thus no gas molecules present around it, no option to open a window and let some fresh air in.
Exactly the same applies to us, earthlings. As cosmonauts of spaceship Earth – soaring through the airlessness – we have the shared responsibility to take good care of the air quality of our atmosphere. Our lives depend on it.

SOURCES:
BUTFIELD Colin & HUGHES Jonnie (authors), Z.K.H. Prins William (foreword); 2021; Eartshot – How to save our planet; Publisher John Murray; London
CONTMEDIA GmbH; Astronomie – een fascinerende reis naar de sterren en planeten; p. 94 – 97; Publisher Komet Verlag GmbH; Keulen
N.N.; Atmosphere of Earth; URL: https://en.wikipedia.org/wiki/Atmosphere_of_Earth ; accessed on December 21st 2024
N.N.; Newton’s law of universal gravitation; URL: https://en.wikipedia.org/wiki/Newton%27s_law_of_universal_gravitation ; accessed on December 21st 2024
DESONIE Dana; 10.3 Pressure and Density of the Atmosphere; URL: https://flexbooks.ck12.org/cbook/ck-12-middle-school-earth-science-flexbook-2.0/section/10.3/primary/lesson/pressure-and-density-of-the-atmosphere-ms-es/ ; accessed on December 21st 2024
N.N.; Armstrong limit; URL: https://en.wikipedia.org/wiki/Armstrong_limit ; accessed on December 21st 2024
N.N.; Space diving; URL: https://en.wikipedia.org/wiki/Space_diving ; accessed on December 21st 2024
N.N.; What is the Karman line?; URL: https://www.worldatlas.com/articles/what-is-the-karman-line.html; accessed on December 21st 2024

Blog 7 - How our atmosphere sustains life on earth

It is high time for a new blog that handles a new Earthshot. Blog 3, 4, 5 and 6 were focused on ‘Reviving of our oceans’. Blog 7, 8, 9 and 10 will be dedicated to the challenge ‘Cleaning our air’. Let’s start by talking about our life’s blanket. The atmosphere.

No air, no life. Air is a gas mixture with a specific composition of different molecules: 78% nitrogen (N2), 20.9% oxygen (O2) – this is what we breathe to live, 0.9% argon (Ar) and 0.1% of other gasses. The gas molecules in our atmosphere have the composition of air.

The sole reason why the air stays in the atmosphere and does not escape to airless space (gas molecules that are not subjected to external forces take on a volume as large as possible), is gravity. This is truly amazing when you think about it. Consider object one: the earth, and consider object two: one gas molecule. These two objects exert a force on one another, they attract each other. The magnitude of this force is directly proportional to the multiplication of both objects’ masses. This means that the bigger the product of these masses (mass object 1 x mass object 2), the bigger the gravitational force. The mass of the earth (mass object 1) is obviously way bigger than the mass of one gas molecule (mass object 2) (50 orders of magnitude bigger, so add 50 zeros). It is thus evidently the mass of the earth that assures the force between the two objects is significantly strong. However, if the gas molecule would be completely weightless, the product would be equal to zero (mass object 1 x 0 = 0), there would be no attracting forces between the two objects and the gas molecule would escape to outer space.
The gravitational force is inversely proportional to the distance (squared) between the two objects. This means that the further the earth and the gas molecule are away from each other, the smaller the force is that they exert on each other. The gas molecules are thus ‘more free’ if their distance to the earth is bigger. Consequently they can move more easily away from each other. This leads to lower air density higher up: per volume unit the amount of gas molecules is smaller. This is called ‘thin’ air and it specifically means that with each breath you inhale less gas molecules of air (and thus oxygen) at the top of the Mount Everest compared to the same inhalation at the foot of this highest mountain in the world.

The atmosphere is thus wrapped as a shell around the earth, formed by gas molecules that are spread out further from each other the higher you go.

Scientists have distinguished different layers in the atmosphere. The layer we are living in is called the troposphere. It reaches up to 15 km above sea level. 75 – 80% of the total mass of gas that is present around the earth is grouped in the troposphere. This layer houses the top of the Mount Everest, flight routes of commercial airplanes and the weather. If you are no astronaut, military air force pilot or extreme adventurer (even more extreme than climbing the Mount Everest), you will not exceed the troposphere in your lifetime. That is not something to be too sorry about because from 18 km of height (Armstrong limit) you cannot survive in our atmosphere without a space suit that regulates the pressure around your body. Search for more details on this topic if you are intrigued – it is all about the boiling of our bodily fluids, true horror.

After the troposphere the stratosphere begins. This layer ends 50 km above sea level. The American Alan Eustace was crazy enough to jump from a balloon hanging in this layer (41.4 km above the earth). There you go, seemingly my definition of an extreme adventurer. Because he choose this height, Alan moved during his free fall back to the face of the earth – thank you gravity – through the ozone layer. This sublayer of the atmosphere is a part of the stratosphere and is defined between 15 and 30 km above sea level. In blog 8 I will explain what is so fascinating about the ozone layer.

The next layer of the atmosphere is called the mesosphere and reaches from 50 up to 85 km above earth’s surface. Thanks to this layer – the density of the gas molecules is just high enough here – most meteors do not come closer than the distance of 50 km to the earth - which to me still sounds freakishly close. They will burn because of the friction that arises between the falling rock and the gas molecules present that are being pushed aside with brute force by the meteor. If you witness this protecting function of the atmosphere, you can make a wish.

After the mesosphere there is the thermosphere which ends at 600 km (some sources report 600 km) above the earth. All gas molecules in this sphere belong to the earth and are thus part of the physical atmosphere. However, a theoretical end of the atmosphere is defined withín the thermosphere, more specifically at 100 km above sea level. This boundary is called the Karman line. The distance is arbitrary chosen and 99.99997% of the total mass of gas molecules that are grouped around the earth, are present below this line. The International Space Station (ISS) is thus, theoretically speaking, located outside of our atmosphere, in outer space. However, at its altitude of 400 km the astronauts will see from time to time a somwhat lost gas molecule pass by. Don’t be fooled though, it belongs to the earth and will most probably never escape its attractional force.

To finalize, let’s add some perspective. The diameter of the earth is 6378 km. The (theoretical) atmosphere rises up to 100 km above the earth’s surface. On a smaller scale you can compare this ratio with a tennis ball and the point of a sharpened pencil. In comparison with the diameter of the earth the atmosphere is thus only a thin shell that wraps around our planet. And it is this layer of gas molecules that sustains life on earth as we know it. In the book Earthshot, astronaut Naoko Yamazaki describes how she, when looking from the right angle with the right light, is able to observe from space our atmosphere, the air we breathe. She continues by comparing the quality of our atmosphere’s air with the quality of the air in a space ship. For the astronauts it is of vital importance that this limited amount of air remains in perfect condition. The ship is floating through vacuum, there are thus no gas molecules present around it, no option to open a window and let some fresh air in.
Exactly the same applies to us, earthlings. As cosmonauts of spaceship Earth – soaring through the airlessness – we have the shared responsibility to take good care of the air quality of our atmosphere. Our lives depend on it.

SOURCES:
BUTFIELD Colin & HUGHES Jonnie (authors), Z.K.H. Prins William (foreword); 2021; Eartshot – How to save our planet; Publisher John Murray; London
CONTMEDIA GmbH; Astronomie – een fascinerende reis naar de sterren en planeten; p. 94 – 97; Publisher Komet Verlag GmbH; Keulen
N.N.; Atmosphere of Earth; URL: https://en.wikipedia.org/wiki/Atmosphere_of_Earth ; accessed on December 21st 2024
N.N.; Newton’s law of universal gravitation; URL: https://en.wikipedia.org/wiki/Newton%27s_law_of_universal_gravitation ; accessed on December 21st 2024
DESONIE Dana; 10.3 Pressure and Density of the Atmosphere; URL: https://flexbooks.ck12.org/cbook/ck-12-middle-school-earth-science-flexbook-2.0/section/10.3/primary/lesson/pressure-and-density-of-the-atmosphere-ms-es/ ; accessed on December 21st 2024
N.N.; Armstrong limit; URL: https://en.wikipedia.org/wiki/Armstrong_limit ; accessed on December 21st 2024
N.N.; Space diving; URL: https://en.wikipedia.org/wiki/Space_diving ; accessed on December 21st 2024
N.N.; What is the Karman line?; URL: https://www.worldatlas.com/articles/what-is-the-karman-line.html; accessed on December 21st 2024

Blog 5 would handle another eartshot. I wrote blog 3 and 4 about water, now it was time to start exploring the air. However, because water is so intriguing – probably secretly my favorite – I write two bonus articles about a sea animal that crosses our oceans. After the corals of blog 3 and 4, now the whales (cetacea), possibly the most amazing animals on this planet earth. Allow me to try to convince you.
This first paragraph should in fact suffice. The blue whale, one of the approximately 90 whale species, is the biggest animal to have ever existed on this earth. They are 2700 times bigger than us, 40 times bigger than an elephant and 30 times bigger than the largest dinosaur, the T-rex. Immense. If this specie would have been, 66 million years ago, suddenly erased from the face of the earth due to a comet strike, there would have been countless blockbusters dedicated to its mythical existence.
Cetacea are defined as big placental sea mammals with a hairless streamlined body, a horizontal tailfin and a blowhole at the top of their head to be able to breathe at the water’s surface. This last feature leads to gorgeous images.
This family is categorized into two subgroups: the baleen whales (mysticeti) and the toothed whales (odontoceti).
The mammals of the first subgroup, the baleen whales to which the blue whale belongs, are larger than the mammals from the second subgroup. They have baleens growing down from their upper jaw which they use to filter from the water large volumes of small food (plankton). They have 2 blow holes and are extremely loud: with a for the animal kingdom record noise level of 180 dB they sing in low frequency (30 – 8000 Hz). Their songs (there are many recordings that can be found online, worth a listen) are both for communication and orientation purposes and their sound can, when voiced at the right depth, travel up to 16 000 km (10 000 miles). Professor Christopher Clark of the Cornell University explains that the whales would use their sounds for ‘echomapping’: by sending their signals and waiting for its return they map the oceans and its shores. With a hydrophone installed in Virginia (East coast of the USA) his research team can hear the song of a whale swimming near the coast of Ireland. The distance between those two places is 5500 km (3400 miles). That is incredible.
Already convinced? If not, then I continue. The mammals of the second subgroup, the toothed whales, have teeth and hunt for fish and other mid-sized sea life. Dolphins are a part of this family (all dolphins are whales) and the orca or killer whale is the biggest dolphin. Also the less known porpoises are toothed whales. The toothed whales have only one blow hole, but are similarly loud as the baleen whales, although they are noisy at higher frequency. Some species can generate and receive sounds up to 160 000 Hz. As a reference, for those of my generation who can still remember the “secret” ringtone we could hear as a 15-year-old while the teacher couldn’t: this one has a frequency of 17 000 Hz. The toothed whales use their sounds for communication as well as for ‘echolocation’: a sent signal bounces off of for example prey to which they consequently can determine the distance. The system is extremely ingenious and has thus been subject to research for multiple decades. Dolphins are even being trained by defense departments to amongst other things assist with identification of underwater mines. They perform this task with utmost precision.
In case further argumentation would be in order. Whales are true world travelers. There are species that travel from the equator to the furthers northern or southern parts of the world and back in the same year. This family of mammals thus adds to their record list, apart from being the biggest and the loudest, also performing the longest mammal migration in the world.
And oh yes, there is something else. Like all mammals whales have lungs. What is difficult to then comprehend is that they are also divers, deep sea divers. There comes record number four: the deepest dive of a mammal recorded by us was performed by a Cuvier’s beaked whale and was 2992 m deep. Other mammals do not even come close to this record number. On average whales are diving for about an hour, but the up till now longest registered dive lasted 222 minutes (more than 3.5 hours). To be able to withstand the water pressure on the lungs deep underwater, whales would purposefully collapse their lungs. Collapsed longs come with a couple of advantages for mammals that our spending time under water, but it also results in a lung capacity of literally 0 l and thus no potential oxygen transfer to the blood at the alveoli (there where the lungs transfer O2 and CO2 with blood). Whales can however, compared to humans, store more oxygen outside of the lungs: they have 2x more hemoglobin, the protein that transports oxygen in the blood, and 10x more myoglobin, the protein that stores oxygen in the muscles. Additionally, they would temporarily stop the blood flow to different organs such as kidneys and the liver. This conserves energy and thus reduces oxygen consumption. Their heartbeat slows down as well and they fold their fins to be able to slide even more aqua dynamically through the water.
All thus pretty cool. And on top of that they could be of assistance to help us rebalance our shared climate. That is story for blog 6.

SOURCES:
DARRAH P.; The fascinating differences between whales and dolphins; URL: https://www.gvi.ie/blog/smb-the-fascinating-differences-between-whales-and-dolphins/; accessed on March 3rd 2024
N.N.; Are dolphins whales?; URL: https://www.ifaw.org/journal/are-dolphins-whales#:~:text=Spoiler%20alert%2C%20dolphins%20are%20in,baleen%20whales%20and%20toothed%20whales.; accessed on March 3rd 2024
N.N.; Whale and dolphin species guid; URL: https://us.whales.org/whales-dolphins/species-guide/#:~:text=There%20are%20around%2090%20species,creatures%20in%20our%20species%20guide.; accessed on March 3rd 2024
N.N.; Difference between whales and dolphins; URL: https://seaworld.com/orlando/blog/difference-between-whales-and-dolphins/; accessed on March 3rd 2024
N.N.; Whale vs dolphin: what’s the difference between these mysterious denizens of the ocean?; URL: https://www.discoverwildlife.com/animal-facts/marine-animals/whale-vs-dolphin-whats-the-difference; accessed on March 3rd 2024
N.N.; How deep can a whale dive?; URL: https://www.nhm.ac.uk/discover/quick-questions/how-deep-can-a-whale-dive.html#:~:text=The%20deepest%20recorded%20dive%20was,1%2C000%20to%202%2C000%20metres%20deep.; accessed on March 3rd 2024
CHAPMAN A.; If the ocean pressure can break human bones, why don’t whales and other species die?; URL: https://www.ucl.ac.uk/culture-online/case-studies/2022/sep/if-ocean-pressure-can-break-human-bones-why-dont-whales-and-other-species-die#:~:text=Whales%20are%20adapted%20in%20amazing,these%20are%20some%20record%2Dbreakers!; accessed on March 3rd 2024
PONGANIS P. J. & KOOYMAN G. L.; How do deep-diving sea creatures withstand huge pressure changes?; URL: https://www.scientificamerican.com/article/how-do-deep-diving-sea-cr/ ; accessed on March 3rd 2024
N.N.; Blauwe vinvis; URL: https://nl.wikipedia.org/wiki/Blauwe_vinvis; accessed on March 3rd 2024
The Editors of Encyclopaedia Britannica; Whale; https://www.britannica.com/animal/whale ; accessed on March 3rd 2024
MBARI R.; Whale communication; https://www.shapeoflife.org/blog/whale-communication ; accessed on March 3rd 2024
CORMIER Z.; The loudest voice in the animal kingdom; URL: https://www.bbcearth.com/news/the-loudest-voice-in-the-animal-kingdom ; accessed on March 3rd 2024
PAVID K. ; Secrets of the deepest-diving whales; URL: https://www.nhm.ac.uk/discover/secrets-of-deep-diving-whales.html; accessed on March 10th 2024
NELSON B.; 14 of the greatest animal migrations – Some creatures travel impressive distances in search of new habitats.; URL: https://www.treehugger.com/greatest-animal-migrations-4869293#:~:text=The%20tiny%20Arctic%20tern%20makes,for%20making%20a%20similar%20journey.; accessed on March 29th 2024

Blog 5 - why whales might be the coolest creatures on earth

Blog 5 would handle another eartshot. I wrote blog 3 and 4 about water, now it was time to start exploring the air. However, because water is so intriguing – probably secretly my favorite – I write two bonus articles about a sea animal that crosses our oceans. After the corals of blog 3 and 4, now the whales (cetacea), possibly the most amazing animals on this planet earth. Allow me to try to convince you.

This first paragraph should in fact suffice. The blue whale, one of the approximately 90 whale species, is the biggest animal to have ever existed on this earth. They are 2700 times bigger than us, 40 times bigger than an elephant and 30 times bigger than the largest dinosaur, the T-rex. Immense. If this specie would have been, 66 million years ago, suddenly erased from the face of the earth due to a comet strike, there would have been countless blockbusters dedicated to its mythical existence.

Cetacea are defined as big placental sea mammals with a hairless streamlined body, a horizontal tailfin and a blowhole at the top of their head to be able to breathe at the water’s surface. This last feature leads to gorgeous images.
This family is categorized into two subgroups: the baleen whales (mysticeti) and the toothed whales (odontoceti).

The mammals of the first subgroup, the baleen whales to which the blue whale belongs, are larger than the mammals from the second subgroup. They have baleens growing down from their upper jaw which they use to filter from the water large volumes of small food (plankton). They have 2 blow holes and are extremely loud: with a for the animal kingdom record noise level of 180 dB they sing in low frequency (30 – 8000 Hz). Their songs (there are many recordings that can be found online, worth a listen) are both for communication and orientation purposes and their sound can, when voiced at the right depth, travel up to 16 000 km (10 000 miles). Professor Christopher Clark of the Cornell University explains that the whales would use their sounds for ‘echomapping’: by sending their signals and waiting for its return they map the oceans and its shores. With a hydrophone installed in Virginia (East coast of the USA) his research team can hear the song of a whale swimming near the coast of Ireland. The distance between those two places is 5500 km (3400 miles). That is incredible.

Already convinced? If not, then I continue. The mammals of the second subgroup, the toothed whales, have teeth and hunt for fish and other mid-sized sea life. Dolphins are a part of this family (all dolphins are whales) and the orca or killer whale is the biggest dolphin. Also the less known porpoises are toothed whales. The toothed whales have only one blow hole, but are similarly loud as the baleen whales, although they are noisy at higher frequency. Some species can generate and receive sounds up to 160 000 Hz. As a reference, for those of my generation who can still remember the “secret” ringtone we could hear as a 15-year-old while the teacher couldn’t: this one has a frequency of 17 000 Hz. The toothed whales use their sounds for communication as well as for ‘echolocation’: a sent signal bounces off of for example prey to which they consequently can determine the distance. The system is extremely ingenious and has thus been subject to research for multiple decades. Dolphins are even being trained by defense departments to amongst other things assist with identification of underwater mines. They perform this task with utmost precision.

In case further argumentation would be in order. Whales are true world travelers. There are species that travel from the equator to the furthers northern or southern parts of the world and back in the same year. This family of mammals thus adds to their record list, apart from being the biggest and the loudest, also performing the longest mammal migration in the world.

And oh yes, there is something else. Like all mammals whales have lungs. What is difficult to then comprehend is that they are also divers, deep sea divers. There comes record number four: the deepest dive of a mammal recorded by us was performed by a Cuvier’s beaked whale and was 2992 m deep. Other mammals do not even come close to this record number. On average whales are diving for about an hour, but the up till now longest registered dive lasted 222 minutes (more than 3.5 hours). To be able to withstand the water pressure on the lungs deep underwater, whales would purposefully collapse their lungs. Collapsed longs come with a couple of advantages for mammals that our spending time under water, but it also results in a lung capacity of literally 0 l and thus no potential oxygen transfer to the blood at the alveoli (there where the lungs transfer O2 and CO2 with blood). Whales can however, compared to humans, store more oxygen outside of the lungs: they have 2x more hemoglobin, the protein that transports oxygen in the blood, and 10x more myoglobin, the protein that stores oxygen in the muscles. Additionally, they would temporarily stop the blood flow to different organs such as kidneys and the liver. This conserves energy and thus reduces oxygen consumption. Their heartbeat slows down as well and they fold their fins to be able to slide even more aqua dynamically through the water.

All thus pretty cool. And on top of that they could be of assistance to help us rebalance our shared climate. That is story for blog 6.

SOURCES:
DARRAH P.; The fascinating differences between whales and dolphins; URL: https://www.gvi.ie/blog/smb-the-fascinating-differences-between-whales-and-dolphins/; accessed on March 3rd 2024
N.N.; Are dolphins whales?; URL: https://www.ifaw.org/journal/are-dolphins-whales#:~:text=Spoiler%20alert%2C%20dolphins%20are%20in,baleen%20whales%20and%20toothed%20whales.; accessed on March 3rd 2024
N.N.; Whale and dolphin species guid; URL: https://us.whales.org/whales-dolphins/species-guide/#:~:text=There%20are%20around%2090%20species,creatures%20in%20our%20species%20guide.; accessed on March 3rd 2024
N.N.; Difference between whales and dolphins; URL: https://seaworld.com/orlando/blog/difference-between-whales-and-dolphins/; accessed on March 3rd 2024
N.N.; Whale vs dolphin: what’s the difference between these mysterious denizens of the ocean?; URL: https://www.discoverwildlife.com/animal-facts/marine-animals/whale-vs-dolphin-whats-the-difference; accessed on March 3rd 2024
N.N.; How deep can a whale dive?; URL: https://www.nhm.ac.uk/discover/quick-questions/how-deep-can-a-whale-dive.html#:~:text=The%20deepest%20recorded%20dive%20was,1%2C000%20to%202%2C000%20metres%20deep.; accessed on March 3rd 2024
CHAPMAN A.; If the ocean pressure can break human bones, why don’t whales and other species die?; URL: https://www.ucl.ac.uk/culture-online/case-studies/2022/sep/if-ocean-pressure-can-break-human-bones-why-dont-whales-and-other-species-die#:~:text=Whales%20are%20adapted%20in%20amazing,these%20are%20some%20record%2Dbreakers!; accessed on March 3rd 2024
PONGANIS P. J. & KOOYMAN G. L.; How do deep-diving sea creatures withstand huge pressure changes?; URL: https://www.scientificamerican.com/article/how-do-deep-diving-sea-cr/ ; accessed on March 3rd 2024
N.N.; Blauwe vinvis; URL: https://nl.wikipedia.org/wiki/Blauwe_vinvis; accessed on March 3rd 2024
The Editors of Encyclopaedia Britannica; Whale; https://www.britannica.com/animal/whale ; accessed on March 3rd 2024
MBARI R.; Whale communication; https://www.shapeoflife.org/blog/whale-communication ; accessed on March 3rd 2024
CORMIER Z.; The loudest voice in the animal kingdom; URL: https://www.bbcearth.com/news/the-loudest-voice-in-the-animal-kingdom ; accessed on March 3rd 2024
PAVID K. ; Secrets of the deepest-diving whales; URL: https://www.nhm.ac.uk/discover/secrets-of-deep-diving-whales.html; accessed on March 10th 2024
NELSON B.; 14 of the greatest animal migrations – Some creatures travel impressive distances in search of new habitats.; URL: https://www.treehugger.com/greatest-animal-migrations-4869293#:~:text=The%20tiny%20Arctic%20tern%20makes,for%20making%20a%20similar%20journey.; accessed on March 29th 2024

Two years ago I lived for a work assignment on the Luzon island in the Philippines. I learned how to dive there, which was on the top of my bucket list. Diving in the Philippines means having the absolute privilege to visit the coral reefs of the region. And I can tell you, the most beautiful gardens on earth are below the water surface. The colors, the textures, the abundance, the ordered disorder, the life it houses, it is truly magnificent.
I did some research. Corals are animals. They have a diameter of 1-10 mm and they have a stomach and a mouth and tentacles which they use to catch little animals to eat. This is the first food source of the organism. One animal is called a polyp and many polyps together form a coral colony. Every polyp in a colony has the same genetic material, they are formed by asexual reproduction. Sexual reproduction takes place when the polyps exert their gametes once a year after which the fertilization takes place at the water surface. The formed ‘planulae’ sink, after floating along the current for a while, and search sturdy underwater surface to nestle. The planula metamorphoses into a polyp and the growth of a new coral colony can start.
Corals living in relatively shallow waters start a collaboration (symbiosis) with zooxhantellae, a type of algae. These algae are plants and perform photosynthesis: using the energy of the sunlight they transform carbon dioxide (CO2) and water (H2O) in sugars (organic material) and oxygen (O2). These sugars are made available for the coral. This is the second food source of the organism.
The presence of these algae is what gives the corals their vibrant colors. When corals are being exposed to a stressful environment for a significant amount of time, they expel their algae. Consequently their own, translucent color is visible. This is coral bleaching. It is important to point out that bleached corals are not dead. However, due to the absence of the zooxanthellae they lack an important food source which makes them weaker: their growth slows down and their immunity is lower. When the stress factor is removed, the zooxanthellae return to the coral an the colony can regain strength and even fully recover.
There are soft and hard corals. Soft corals have their polyps exposed, waving freely in the water. Hard corals form an exoskeleton to protect their polyps. This skeleton grows chemically: calcium ions present in the sea water react with carbonate ions to form calcium carbonate (Ca2+ + CO32- -> CaCO3). The formed CaCO3 has an aragonite crystal structure. There is no yet scientific consensus about the exact mechanism taking place that forms this skeleton, but a lot of interesting research is already published and ongoing.
Corals are being threatened and that worries us. But why exactly? Why are they important?
Even though coral reefs cover only 0.1% of the ocean surface, 25% of the ocean life is directly dependent on it for food, housing, hiding, reproduction,… This is the first reason for conservation: the coral reefs form a unique ecosystem with enormous biodiversity. Secondly, the reefs protect the land that lies behind it. They absorb the energy of waves, storms and even tsunamis and protect in this manner the coast line against erosion and destruction. Thirdly, there is a big economic dependence on the coral reefs. It is estimated that the corals generate € 9.9 billion/year. And fourthly, there is a lot of hope that scientists are able to one day use the toxins present in the corals to produce important medicines.
There are thus more than enough important reasons, on top of the conservation of natural beauty, to protect the coral reefs and their ecosystem.

SOURCES:
BUTFIELD Colin & HUGHES Jonnie (authors), Z.K.H. Prins William (foreword); 2021; Eartshot – How to save our planet; Publisher John Murray; London
N.N.; Koraalrif; URL: https://nl.wikipedia.org/wiki/Koraalrif; accessed at January 15th 2024
N.N.; Coral; URL: https://en.wikipedia.org/wiki/Coral; accessed at January 15th 2024
National Ocean service ; Corals tutorial ; URL : https://oceanservice.noaa.gov/education/tutorial_corals/welcome.html; accessed at January 15th 2024
Coral guardian; Why are corals so important?; URL: https://www.coralguardian.org/en/coral-reef-important/; accessed at January 15th 2024
Flower Garden Banks National Marine Sanctuary; Coral bleaching; URL: https://flowergarden.noaa.gov/education/bleaching.html; accessed at January 15th 2024
Flower Garden Banks National Marine Sanctuary; Spawning oberservations; URL: https://flowergarden.noaa.gov/education/spawningobservations.html; accessed at January 15th 2024
MASS T.; GIUFFRE A. J. ; e.a. ; July 28th 2017 ; Amorphous calcium carbonate particles form coral skeletons ; Edited by Andrew H. Knoll, Harvard University, Cambridge, MA
LIPPSETT Lonny; November 12th 2018; How do corals build their skeletons? Subtle architecture affects reefs’ ability to withstand threats; URL: https://www.whoi.edu/oceanus/feature/how-do-corals-build-their-skeletons/; accessed at January 15th 2024

Blog 3 - Defintion: what are corals and why are they important

Two years ago I lived for a work assignment on the Luzon island in the Philippines. I learned how to dive there, which was on the top of my bucket list. Diving in the Philippines means having the absolute privilege to visit the coral reefs of the region. And I can tell you, the most beautiful gardens on earth are below the water surface. The colors, the textures, the abundance, the ordered disorder, the life it houses, it is truly magnificent.

I did some research. Corals are animals. They have a diameter of 1-10 mm and they have a stomach and a mouth and tentacles which they use to catch little animals to eat. This is the first food source of the organism. One animal is called a polyp and many polyps together form a coral colony. Every polyp in a colony has the same genetic material, they are formed by asexual reproduction. Sexual reproduction takes place when the polyps exert their gametes once a year after which the fertilization takes place at the water surface. The formed ‘planulae’ sink, after floating along the current for a while, and search sturdy underwater surface to nestle. The planula metamorphoses into a polyp and the growth of a new coral colony can start.

Corals living in relatively shallow waters start a collaboration (symbiosis) with zooxhantellae, a type of algae. These algae are plants and perform photosynthesis: using the energy of the sunlight they transform carbon dioxide (CO2) and water (H2O) in sugars (organic material) and oxygen (O2). These sugars are made available for the coral. This is the second food source of the organism.

The presence of these algae is what gives the corals their vibrant colors. When corals are being exposed to a stressful environment for a significant amount of time, they expel their algae. Consequently their own, translucent color is visible. This is coral bleaching. It is important to point out that bleached corals are not dead. However, due to the absence of the zooxanthellae they lack an important food source which makes them weaker: their growth slows down and their immunity is lower. When the stress factor is removed, the zooxanthellae return to the coral an the colony can regain strength and even fully recover.

There are soft and hard corals. Soft corals have their polyps exposed, waving freely in the water. Hard corals form an exoskeleton to protect their polyps. This skeleton grows chemically: calcium ions present in the sea water react with carbonate ions to form calcium carbonate (Ca2+ + CO32--> CaCO3). The formed CaCO3 has an aragonite crystal structure. There is no yet scientific consensus about the exact mechanism taking place that forms this skeleton, but a lot of interesting research is already published and ongoing.

Corals are being threatened and that worries us. But why exactly? Why are they important?

Even though coral reefs cover only 0.1% of the ocean surface, 25% of the ocean life is directly dependent on it for food, housing, hiding, reproduction,… This is the first reason for conservation: the coral reefs form a unique ecosystem with enormous biodiversity. Secondly, the reefs protect the land that lies behind it. They absorb the energy of waves, storms and even tsunamis and protect in this manner the coast line against erosion and destruction. Thirdly, there is a big economic dependence on the coral reefs. It is estimated that the corals generate € 9.9 billion/year. And fourthly, there is a lot of hope that scientists are able to one day use the toxins present in the corals to produce important medicines.

There are thus more than enough important reasons, on top of the conservation of natural beauty, to protect the coral reefs and their ecosystem.

SOURCES:
BUTFIELD Colin & HUGHES Jonnie (authors), Z.K.H. Prins William (foreword); 2021; Eartshot – How to save our planet; Publisher John Murray; London
N.N.; Koraalrif; URL: https://nl.wikipedia.org/wiki/Koraalrif; accessed at January 15th 2024
N.N.; Coral; URL: https://en.wikipedia.org/wiki/Coral; accessed at January 15th 2024
National Ocean service ; Corals tutorial ; URL : https://oceanservice.noaa.gov/education/tutorial_corals/welcome.html; accessed at January 15th 2024
Coral guardian; Why are corals so important?; URL: https://www.coralguardian.org/en/coral-reef-important/; accessed at January 15th 2024
Flower Garden Banks National Marine Sanctuary; Coral bleaching; URL: https://flowergarden.noaa.gov/education/bleaching.html; accessed at January 15th 2024
Flower Garden Banks National Marine Sanctuary; Spawning oberservations; URL: https://flowergarden.noaa.gov/education/spawningobservations.html; accessed at January 15th 2024
MASS T.; GIUFFRE A. J. ; e.a. ; July 28th 2017 ; Amorphous calcium carbonate particles form coral skeletons ; Edited by Andrew H. Knoll, Harvard University, Cambridge, MA
LIPPSETT Lonny; November 12th 2018; How do corals build their skeletons? Subtle architecture affects reefs’ ability to withstand threats; URL: https://www.whoi.edu/oceanus/feature/how-do-corals-build-their-skeletons/; accessed at January 15th 2024

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Blog 16 - Explain to me the Paris Agreement

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Blog 3 - Definition: what are corals and why are they important?

Blog 3 - Defintion: what are corals and why are they important