Happy New Year 2020 : a (long) letter to 16 year old people of today.
Dear young friend, I would like to look both backwards and forward and think of climate change science and society.
When I was your age, a 16 year old high school student, I enjoyed reading science popularization magazines. In 1987, new research was emerging on the Earth's space observations, climate modelling, Antarctic ice cores.
I was also fascinated by clouds - I could spend hours watching clouds.
My wonder for nature’s beauty and my enthusiasm for science developments are clearly at the origin of my motivation to be a climate scientist.
Knowledge on climate change was much more limited than today when I was your age. It is extremely impressive to consider climate science achievements of the past decades, thanks to support by governments for basic research.
We now have the capacity to monitor key aspects of the climate system: changes in the Earth’s energy budget, changes in global and regional climate, from the top of the atmosphere to the depths of oceans, from the poles to the tropics.
This has been achieved thanks to technological progress, international cooperation, including in situ monitoring and remote sensing from space.
We also benefit from impressive progress in process based understanding, theoretical developments, as well as the revolution of numerical modelling. The field of climate modelling has expanded in the second part of the 20th century.
Climate and Earth system models play a key role to understand how the climate sytem operates, why it has changed in the past, how it has affected the intensity and likelihood of extreme events, and what are physically plausible future climate changes, depending on our choices.
World media have celebrated last year the 50th anniversary of the first footstep of a human being on the moon, as a major achievement.
No such echo has been given to the Charney report, released in the same year, which was of the first scientific assessments of the role of greenhouse gases emitted as a result of human activities on global climate.
The Charney report estimated the range of climate sensitivity – a metrics which measures the most probable warming at the Earth’s surface resulting from a doubling of the atmospheric CO2 concentration above pre-industrial levels to be near 3°C with a likely range of ± 1.5°C.
This range has been supported by more evidence from paleoclimate, observations, theory and much more sophisticated numerical climate models.
Some of the latest climate models, which better represent climate processes, have a larger spread in their response to greenhouse gas emissions.
It is an opportunity to learn and better understand climate sensitivity, given its implication for future risks and our remaining margin of action, through breakthroughs in basic climate research.
Our knowledge of past climates demonstrate the unprecedented perturbation already caused by human activities on the Earth’s climate, altering the Earth’s energy budget.
Recent studies have confirmed that the current 1°C rise of global mean surface temperature since the end of the 19th century is larger, faster, and more globally synchronous than at any other time of the past two millennia.
Our best estimate is that all of the ongoing warming is due to human activities. We already see the reality of this changing climate, with changes in regional trends, and characteristics of extreme events which affect ecosystems and livelihoods everywhere.
In France, your secondary education final exam was postponed due to a record breaking heat wave, made more likely and more intense by human-induced climate change.
Dear young friend, you are a child of the Anthropocene.
When I was a teenager, governments wanted to be provided the best state of scientific knowledge. They established the Intergovernemental Panel on Climate Change in 1988.
It is remarkable that the key patterns of what has been observed in the last 30 years had been correctly anticipated in the first crude ocean-atmosphere projections published in 1989.
Today, with more than 20 000 peer review publications with the key word « climate change », relevant knowledge production from all disciplines is accelerating.
It reflects the broad development of climate change sciences, including understanding impacts and risks, exploring options for risk management and enhancing resilience,
links with sustainable development, preserving ecosystems and improving human well being while reducing greenhouse gas emissions towards carbon neutrality.
With more than 20,000 peer review publications per year on this topic, more than ever, we need internationally coordinated efforts to assess the state of knowledge, from the critical analysis of the scientific literature.
This is the mandate of the Intergovernmental Panel on Climate Change, which has celebrated its 30th anniversary last year, and is currently producing herculean efforts to produce a set of reports within its Sixth Assessment cycle.
We have just completed the first three special reports of this cycle.
Dear young friend, imagine behind me the 300 authors of these reports, and all those who have contributed to them, as they rely altogether on the analysis of 20 000 scientific publications, and have received 70 000 review comments from thousands of researchers worldwide.
I am very thankful for their volunteer work and dedication.
In my mind, these reports are prepared not just for policy makers in governments, but for the world’s citizens, and for your generation.
By identifying robust findings as well as limits to current knowledge and knowledge gaps, they contribute to the maturation of climate change science.
Dear young friend, you do not grow up in the same world as mine when I was 16. I could only find information in classic media, encyclopedias and libraries. Today, most people around the world are using social media to have access to information.
You are surrounded by a wealth of information, easily accessible through the internet. In a world of social media and fake news, you need more than ever to understand the difference between facts and opinions.
The voice of science on social media is weak. Your young voices are powerful to that science is not ignored.
Science is unique.
The preparation of IPCC reports follows science principles to deliver assessments of the best state of knowledge in a way that is rigorous, exhaustive, objective and transparent. Each finding is associated with a level of confidence.
This IPCC cycle is unique. We have brought together, for the first time, scientists from all disciplines to provide the most integrated assessments to date in these three special reports completed in 2018 and 2019.
Why does the IPCC special report on global warming of 1.5°C matter for you ?
It shows that for your world every fraction of warming matters, every year matters, every choice matters.
It shows that for your world every fraction of warming matters, every year matters, every choice matters.
At the current rate of warming, 0.2°C per decade, global warming will reach 1,5°C between around 2030 and 2050. At that time, you will be my age. A 1.5°C warmer world will be your world.
This report illustrates how much every half a degree matters in terms of future impacts and risks.
It shows that for the preservation of healthy ecosystems, and for health, livelihoods, food security, water supply, human security and economic growth, there are clear benefits to limit global warming at 1.5°C compared to 2°C or above.
Risks are disproportionately higher in some regions, such as drylands (also around the Mediterranean sea), for small island developing states, least developed countries and the Arctic.
Limiting warming to 1.5°C compared to 2°C would avoid exposing several hundred million people susceptible to poverty to climate-related risks. Major adaptation efforts are needed to manage risks, even for 1.5°C global warming.
This report also illustrates how much every year matters in terms of greenhouse gas emissions.
Due to the cumulative effect of CO2, stabilizing global warming can only be achieved by sharp reductions in emissions and reaching net zero emissions as soon as possible.
It also implies to reduce the net effect on climate from other emissions which also cause air pollution, which would have immediate benefits for air quality and your health.
If pledges of governements expressed in 2015 during the Paris Agreement are realized, global greenhouse gas emissions would continue to increase until 2030.
The current level of ambition to reduce slowly the rate of greenhouse gas emissions would lead to global warming of more than 3°C by 2100 and would therefore not respect the goal of the Paris Agreement.
Limiting global warming well below 2°C would imply to reduce CO2 emissions by 25% by 2030 and reach net zero by 2070. Limiting global warming to 1.5°C would imply to reduce CO2 emissions by 50% by 2030 and reach net zero by 2050.
It would require rapid, far-reaching and unprecedented transitions in energy, land use, urban, industry and infrastructure systems, using a range of technologies and behavioural changes. With more than 40 billion tons CO2 emitted every year in the atmosphere, every year matters.
What is going to happen in the coming year(s) will shape your world. More mitigation now, more leeway for you. Less mitigation now, more climate change to live with, to cope with.
Finally, this report shows how much every choice matters. It builds on the intersection between climate change impacts, options for adaptation, options for mitigation, and sustainable development goals.
By using this multi-dimensional analysis, it shows how ethical, fair and just transitions can be designed.
Different choices in terms of climate action can lead to either positive or negative outcomes with other sustainable development goals.
In each context, a careful mix of measures to adapt to climate change and reduce emissions can help achieve sustainable development goals through low carbon, climate resilient development pathways, protecting those who are most vulnerable, as well as ecosystems and biodiversity.
Our assessment shows clearly that the highest benefits are achieved when we reduce energy demand, consumption of non renewable materials, and pressure on land through environmentally-friendly and healthy diets.
Dear young friend, this is not exactly what advertisements surrounding you are promoting.
We know enough to act, but we also need support for science to tackle knowledge gaps identified in each IPCC report.
For instance, how will development choices affect magnitudes and patterns of climate-related risk ? What will be the interactions between climate change, land use change, vegetation health and carbon storage in terrestrial ecosystems ?
This is a great transition to the second IPCC special report of this cycle, focused on climate change and land.
We show that land is under growing pressure, with human activities affecting 70% of ice free land areas, of which 25% are already degraded.
The way we produce food, and what we chose to eat contributes to the destruction of ecosystems and loss of biodiversity. Our food system accounts for around 30% of global greenhouse gas emissions.
Land is part of solution, and there are multiple options to act through sustainably intensified production, reduced food loss and waste, and shifts to healthy and environmental-friendly diets, reducing pressure on land.
This report is about climate change in your landscape, climate change on your farm, climate change on your plate.
Impacts will increase with more warming, due to water scarcity, intensified wildfire, permafrost thaw. In a warming world, the ability of land to store carbon can decline.
Climate change will induce declines in crop yields, higher food prices, and perturbations in food supply. Some regions, countries and communities have limited capacity to deal with the negative effects of climate change.
You will be best placed to tackle climate change in a world with an overall focus on sustainability.
Near-term actions to promote sustainable land management will help reduce the loss of biodiversity, also through restoring natural ecosystems and their capacity to store carbon.
There are limits to the scale of energy crops and afforestation that could be used. It also takes time for trees and soils to store carbon effectively.
Better land management can release agricultural land for afforestation and bioenergy so as to not impact on your food security and your natural heritage, biodiversity.
Let us now move to the third Special Report of this IPCC cycle.
The ocean and cryosphere – the frozen parts of our planet – might feel remote to some of you.
But they impact all of us, for weather and climate, food and water, for energy, trade or transport, for health and wellbeing, for culture and identity.
The ocean and cryosphere have been taking the heat for climate change for decades. The consequences for nature and humanity are sweeping and severe.
Man-made climate has a major footprint on the systems that we depend upon – from the top of the mountains to the depth of ocean. These changes will continue along your lifetime and for generations to come.
Sea level rise, and many other essential life-sustaining aspects of the ocean and cryosphere are at stake.
If we reduce emissions sharply, consequences for many people and their livelihoods will still be challenging. But they will be potentially more manageable for those who are most vulnerable.
Even if greenhouse gas emissions decline sharply, extreme high sea level events which occurred only once per century in the past will occur in many coastal regions once per year by 2050.
The level of coastal risk will depend on both greenhouse gas emissions, and the implementation of local responses in communities and cities at the coast to reduce exposure and vulnerability.
For your generation, cooperation is going to be particularly important, because people with the highest exposure and vulnerability are often those with the lowest capacity to respond.
Our report provides the best available scientific knowledge to empower people, your communities and governments to tackle the unprecedented transitions in all aspects of society.
Combining scientific with local and indigenous knowledge is key to develop suitable options to manage climate change risks and enhance resilience.
This is the first IPCC report that highlights the importance of education to enhance climate change, ocean and cryosphere literacy. Dear young friend, please ask to learn more on these essential issues.
We know enough to act now,
but new knowledge is needed to better understand permafrost carbon feedbacks, to better understand the response of the southern ocean and Antarctic ice sheet and their implications for global climate and sea level rise, for compound risks and cascading impacts.
We also need to better understand the efficacy and limits of strategies to enhance resilience.
"This report highlights the urgency of prioritising timely, ambitious, coordinated and enduring action".
Dear young friend, this is the final sentence of this report, approved by all governements. I had you in mind when it was approved. We need urgent action.
Despite decades of new knowledge development confirming that we are causing global climate change, and 30 years of IPCC assessments, global emissions of most greenhouse gases keep rising.
It sometimes looks like the unfolding of a Greek tragedy, where we see happening what had been anticipated decades ago by climate and Earth system modelling.
The small window of opportunity to limit global warming at low levels is closing fast with rising emissions. Failure to act today to reduce emissions will increase the burden on your generation.
You will have to face escalating consequences of higher levels of global warming, such as the irreversible loss of ecosystems, increasing need for crisis management, and more costly, difficult and risky options to manage risks.
You may know more on climate change than the mayor of your city, or the prime minister of your country.
Climate change literacy remains low amongst decision makers and the general public. Our science is not always part of school and university curricula. Climate change skills are not part of the international benchmarking of education programmes and universities.
We are facing merchants of doubt, very efficient to use media and social networks to spread misinformation on the reality of climate change and its causes. Sometimes, scientists from other fields of expertise have been the most active to attack climate science and spread denial.
There are great stories to be deconstructed.
The story which denies the evidence that our activities have profoundly disrupted atmospheric composition and climate, with impacts that are already visible and which will continue to grow with more global warming.
The story that governments, informed by information produced by the scientific community, will bravely make the decisions necessary for the long-term common good.
The story of fatalism and powerlessness, which plays on our fears of committed changes and on the inability of decision-makers to act at the scale of the issues at stake.
We must deconstruct these stories, and show how to deploy all the levers of action, at all scales, now, wisely, collectively, and design the solutions that can be deployed tomorrow through research and innovation.
Improved monitoring, understanding & modelling of the Earth system is part of these solutions. Climate services, providing climate information relevant for decision making, including an assessment of uncertainties, at regional and sectoral scales, are also part of these solutions
We need science to be more easily accessible to everyone. We need to make sure that our publications are publicly accessible to all citizens, as a fair return to their support for science through their taxes.
We need to support scientists so that they are trained to engage in social media, participatory approaches, and recognize these activities to be part of their jobs.
We need new mindsets with solid understanding of climate change risks and solutions.
We need to support the integration of research activities, at the interface between climate and climate change sciences, including social sciences, at the interface between climate and biodiversity, to better understand nature based solutions.
We need to build bridges between the academic world, practioners, engineers.
We need to empower you, our students, young people, so that you understand the science, and you experiment and learn how to act in support of sustainability.
We need to work with cities where our research centers and universities are located, in order to accelerate transitions where we live.
We need to learn what are the needs of society, and develop new approaches for the co-design and co-production of knowledge.
Scientists are also sometimes the worst examples of cognitive dissonance, working on climate change while travelling by plane around the world to attend more and more meetings. We need to reflect on our own practices.
How can we deploy pathways to reduce emissions associated with our research activities, while producing both basic knowledge breakthroughs and knowledge supporting societal transformation?
How can we better use solutions of the 21st century such as videoconferencing to stimulate intellectual exchanges, cooperation, emulation, capacity building in all countries?
What are the pathways of universities, research institutes, national and international research organisations to reduce emissions and play their roles in climate action, aligned with the Paris agreement?
What will be the state of the your world, the state of biodiversity, the state of humanity in a century from now, in 2120 ?
Will we have built resilience and managed risks ?
Will we have sharply reduced greenhouse gas emissions and improved well being for all, leaving no-one behind, through technological, frugal and social innovation ?
Will we have used all forms of knowledge, wisdom and science for human progress ?
All this will depend on our actions in the coming year(s) and decades.
As scientists, we must claim to have a voice in the affairs of our cities, to carry the voice of science, to put science at the service of the transformations of our societies,
because we must act, in a lucid and responsible way, for the greatest challenge that we must succeed to overcome together.
Dear young friend, I understand your impatience, I understand your call for action. Because it is all about your world.
