This is the new “bible” of climate change. The summary of the Intergovernmental Panel on Climate Change’s (IPCC) Sixth Assessment Report was released on Monday, March 20 and will become the benchmark for scientific knowledge on global warming and its consequences.
This document is the result of a compilation of thousands of studies and researches in this field conducted since the end of 2014 and the publication of the previous summary by IPCC experts.
The authors of this “Summary for Policymakers” point to the magnitude of the damage these climate changes have already caused in a world experiencing temperatures that have already increased by 1.1°C compared to the 1850-1900 reference period.
They also underline the inadequacy of countries’ efforts to meet the commitments made at the various climate summits. The target of staying within 1.5°C to 2°C of temperature rise by 2100 seems increasingly unachievable. “The temperature rise could exceed 1.5 °C within ten years if annual CO2 emissions remain at current levels,” explains Gerhard Krinner, a researcher at the Institute for Environmental Geosciences and one of the authors of the IPCC report.
“The benefits far outweigh the costs”
But all is not black in this politically highly sensitive document, which was carefully considered before publication. “There are several available and effective options to reduce greenhouse gas emissions and adapt [le monde] on man-made climate change,” even the IPCC states in the preamble of this document.
In particular, it is “the first time that the IPCC has taken a stand and generally considered it beneficial to make an effort to keep temperatures below the 2°C rise threshold,” stresses Jean-Charles Hourcade, climate economist at CNRS who helped prepare the report contributed.
In fact, these scientists have so far only been content with assessing how the climate goals can be achieved and estimating how realistic this is. This time, “they claim that the benefits of measures to limit temperature rise more than outweigh the costs,” says Jean-Charles Hourcade.
A position clearly aimed at persuading decision-makers to do more to reform and invest in a greener future. Even if these changes will lead to profound social upheavals in the short term.
According to the IPCC, the best program of action would be “to divert the bulk of investment [environnementaux] in developing countries,” assures Jean-Charles Hourcade. In these areas, every dollar invested brings the best return for the planet and the economy.
The key data of the IPCC report
1.1°C. Between 2011 and 2020, the global temperature was 1.1°C higher than between 1850 and 1900. This last period serves as a reference for all the models that have been developed by scientists to calculate our climate trajectory and to determine whether we are, for example, temperature increases to 1.5°C or 2°C.
3.2°C. This is the mean temperature rise expected by 2100, taking into account all the measures countries have already taken to limit their emissions.
In fact, according to calculations by IPCC scientists, it should be between 2.2 and 3.5 °C. In any case, the efforts made so far are far from sufficient to reach the target of a maximum warming of 2°C set in 2015 during the COP21 in Paris.
0.45°C. The IPCC claims that for every 1,000 billion tons of CO2 emitted by human activity, global temperatures rise by 0.45°C.
Based on CO2 emissions alone in 2018 – 38 billion tons – the temperature rise would exceed 1.5°C within 23 years. In reality, however, this threshold is likely to be reached within ten years due to other greenhouse gases such as methane, which also contribute to global warming.
3.7mm This is the annual sea level rise due to global warming between 2006 and 2018, the IPCC notes. The speed of this phenomenon has accelerated significantly, since between 1971 and 2006 this annual increase was almost half as fast.
Overall, sea level has risen by 20 cm since the beginning of the 20th century. In other words, almost a fifth of the total increase took place between 2006 and 2018 (4.4 cm).
6 meters. In the very long term, sea levels could rise by almost 6 meters even if humanity manages to limit temperature rises to a maximum of 2°C.
In fact, the IPCC report indicates that in this scenario, the water level should rise by 3 to 6 meters over the next 2,000 years. Enough to dramatically alter the geography of the globe and make some of the land that has now surfaced disappear.
Even limiting temperature rise to 1.5°C, sea levels would still rise sharply – between 2 and 3 meters – 2,000 years from now.
Between 3.3 and 3.6 billion Humans live in contexts that make them highly vulnerable to the effects of global warming. Almost half of the world’s population is therefore expected to be affected by extreme weather events such as drought, heavy rain or earthquakes.
It is the populations living in the poorest countries who are most at risk, the IPCC scientists emphasize again. Between 2010 and 2020, mortality related to floods, droughts or even hurricanes was 15 times higher in the poorest countries than in the regions of the so-called rich countries.