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🤔 What is this IPCC report everyone is talking about?
👉 This is the first part of the new IPCC report (the previous synthesis report dates back to 2014), which outlines our understanding of climate change, its causes, and its physical consequences. Two more parts will be published by the end of 2022: the second will focus on the implications for biodiversity and human societies, as well as adaptation solutions, and the third will describe the state of the art regarding solutions to combat global warming by limiting emissions and envisioning a sustainable future.
🤔 But aren't the people at the IPCC just ideological environmentalists?
👉 No: The report is scientifically unassailable. An immense amount of work has gone into it (234 authors, 14,000 references…). It is an exemplary synthesis of existing scientific literature that establishes a true scientific consensus. Each statement in the report is carefully weighted by the authors' level of confidence in that statement ("it is {likely / very likely / extremely likely} that…"). We can therefore trust it. This report goes far beyond partisan agendas.
🤔 Is there still any doubt about human influence on climate change?
👉 No: One of the first sentences of the report sets the tone: "It is unequivocal that human influence has warmed the atmosphere, ocean and land." And this is not simply the acceleration of a natural process: the average temperature is rising almost linearly with the amount of CO2 emitted by humans. We have entered the warmest period in over 100,000 years, and the trend is not about to reverse.
🤔 What are the predicted consequences?
👉 The first obvious consequence of climate change is a rise in average temperatures. Several scenarios are considered depending on the evolution of greenhouse gas emissions, ranging from +1.4°C to +4.4°C by 2100 compared to the pre-industrial period. But be careful: these are only average values. This rise is not uniform across all regions. In particular, temperature increases in continental and polar zones will be much greater. Furthermore, heatwaves are set to intensify. We will have to wait for the second part of the report to get an idea of the consequences of these changes on our societies, but it is already clear that the changes will be so radical in some regions that we cannot simply say that "humans will adapt."
Other consequences include a rise in sea levels, between 0.5 meters and 1 meter by 2100 depending on the scenario. And if we look ahead to 2300, the rise could reach up to 7 meters, or even 15 meters in a scenario that cannot be ruled out. I'll let you imagine the consequences. At 7 meters, the island of Noirmoutier has practically disappeared, and only the center of the city of Arles remains above water. And in some countries, the situation will be dramatic.
It should also be noted that global warming is accelerating the water cycle, which will increase precipitation in many regions. But once again, the consequences must be studied precisely on a region-by-region basis, because in other areas, drought periods will intensify.
🤔 But I had a terrible summer! I don't believe any of this.
👉 And yet: the case of France in July and August 2021 was very specific, due to an exceptional meteorological phenomenon known as a "cold drop." All around us, heatwaves were indeed occurring. There were even fears of a pasta shortage due to the heatwave in Canada and the floods in Europe, which severely impacted global durum wheat production.
Furthermore, the IPCC report reminds us that temperature variability over a decade is significant. So, beware of false impressions, and let's remain attentive to general trends and the common good.
🤔 Is it still possible to reverse the trend?
👉 Yes and no. The culprits are known. They are primarily emissions of carbon dioxide, methane, and nitrous oxide. Since the correlation between global warming and these emissions is well-established, it is easy to calculate a carbon budget that must not be exceeded, depending on the scenario we choose to pursue.
We therefore know what remains to be done: work to reduce these emissions in our activities. This starts with a collective awareness. Then, it is up to everyone, whether an individual or an industrial player, to commit to reducing their own emissions by implementing the following three-step approach:
1. Measure (Collect all the data necessary for an accurate calculation of our carbon emissions)
2. Analyze (Identify the most significant emission sources)
3. Take action (Implement and monitor an emissions reduction action plan).
However, while we can limit the scale of climate change, underlying trends have already been set in motion and are irreversible, particularly in our oceans (rising temperatures, acidification, deoxygenation, etc.). Consequently, no matter what we do, the ice sheets will continue to melt for centuries or even millennia, and sea levels will continue to rise. All we can do today is limit the damage. And that is already a huge achievement!
🤔 Fair enough. I need to learn more. How do I go about it?
👉 There is no way you should try to read the full report (3,949 pages!), which should be viewed as an encyclopedic resource. Many summaries are available. We must mention the summary of 42 pages (in English) published by the IPCC, which is a bit technical but remains readable if you have a good grasp of English. It includes many charts and figures. If you only have five minutes, at least read their super-summary of 2 pages. Among the French-language sources, a special mention goes to BonPote which has created a summary accessible to everyone.