The IPCC is submitting a special report on Monday, commissioned by the UN to raise the stakes of a stabilized global warming at 1.5 ° C.
Until now, the IPCC had looked into the impacts of global warming by taking into account temperature increases of + 2 ° C by 2100, see more.
Scenarios that are more in line with the trajectory that is ours today.
This new IPCC report then makes it possible to realize the impacts that we would avoid by stabilizing global warming at 1.5 ° C.
Yet another call to action… The Intergovernmental Panel on Climate Change (IPCC) is publishing a new scientific report on Monday on the challenges of global warming.
This time, the IPCC looked at 6,000 scientific publications in order to pose the challenges of a stabilized global warming at 1.5 ° C by 2010 compared to the pre-industrial era.
In short: what impacts we would avoid by stabilizing global warming at 1.5 ° C rather than 2 ° C or even 4 ° C, a trajectory on which we are much more today.
Answer this Monday.
In the meantime,
20 Minutes
recapitulates you all the context of this new report.
The IPCC… What is it again?
The Intergovernmental Panel on Climate Change was created in 1988 at a time when people were beginning to realize the risks of too much greenhouse gas accumulation in the atmosphere. The IPCC is both an initiative of scientists aware of being faced with a problem that is difficult and important to publicize and of a political decision, this group of experts being placed under the responsibility of the World Meteorological Organization (WMO) and of the United Nations Environment Program (UNEP). Its official mission? Evaluate without bias and in a methodical, clear and objective manner, the scientific, technical and socio-economic information that is necessary for us to better understand the risks linked to global warming of human origin.
"The IPCC does not produce scientific knowledge as such," specifies Roland Séférian, climatologist at Météo France and co-author of chapter 2 of the report submitted on Monday.
It makes an assessment of the existing scientific literature.
This is not a simple compilation of studies released to date on global warming and its consequences, the IPCC draws the substance from it.
»It then provides political decision-makers with a common base of scientific knowledge on global warming on which there is consensus.
Who works at the IPCC and how many reports have been produced since 1988?
"The IPCC has only ten permanent members," indicates Hélène Guillemot, historian and sociologist of science at the Center Alexandre Koyré.
But for each report, this office collaborates with a hundred international researchers whose writings are proofread by other scientists.
And there we count in thousands.
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The IPCC has three working groups.
“The first concerns the physics of the climate and the observations and forecasts of climate change,” continues Hélène Guillemot.
It is often the work of this first group that we talk about in the media.
The second looks at the impacts of climate change.
On societies, ecosystems etc.
The third group, which we should talk about a lot more in the future, deals with responses to climate change.
"
This group of climate experts produces two types of publications.
On the one hand, there are the assessment reports, to be seen as an inventory at time T of our scientific knowledge on climate change.
Five evaluation reports have been published to date.
The last date of November 2014. He estimated at 4.8 ° C the increase in average temperatures at the surface of the planet by 2100 compared to the period 1986-2005, if greenhouse gas emissions continue at their current pace.
On the other side, there are the special reports commissioned by the UN on specific topics.
The one published on Monday falls into this second category.
Why is the new report published on Monday promising to be significant?
In a document of 400 pages and based on 6,000 scientific studies, the IPCC looked this time at the objective of a global warming of 1.5 ° C still compared to the pre-industrial era. The order was placed during the COP21 in Paris, during which the member states of the United Nations pledged to reduce their emissions to stay well below 2 ° C. “Until then, most of the scientific literature, including the IPCC report of November 2015, studied the impact of global warming based on scenarios of temperature increases by 2100 much greater than 1.5 ° ”, explains Roland Séférian. Trajectories of 3 ° C or even 4 ° C. On the other hand, we lacked scientific literature on the impacts of a warming to 1.5 ° C. "
By correcting the situation, this new report from the IPCC points to the impacts that we would avoid by stabilizing the warming at 1.5 ° C rather than at 2 ° C or even 3 °. Whether it is a question of the extent of heat waves, the extinction of species, agricultural productivity, rise in sea level… “There is a big difference between the 1.5 ° and 2 ° scenario. , slipped this week, by way of teasing, Laurence Tubiana, French diplomat, architect of the Paris Agreement of 2015 on the climate.
This new report also details the possible efforts and trajectories to limit global warming to 1.5 °.
Roland Séférian sees it as a major novelty in the work of the IPCC "From 1988 to 2015, this group of climate experts mainly sought to strengthen its observation on the existence of climate change and its consequences", observes the climatologist .
There are no more debates today, so that the IPCC is now moving on to another stage: the analysis of solutions, the evaluation of the costs and benefits that would imply a global warming limited to 1.5 ° C.
How will political decision-makers welcome this new IPCC report?
It will be possible to fully judge this on Monday.
But negotiations have already started in Incheon (South Korea), where political representatives of UN member states have been peeling the IPCC report for a week before giving their approval.
The procedure is classic.
"The publication of an IPCC report is accompanied each time by a summary for decision-makers, much shorter and which must be approved by the delegates of all countries," explains Hélène Guillemot.
Discussions do not normally focus on scientific data but on questions of formulation, the way of presenting things being able to offend the sensitivity of certain countries.
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For Pierre Cannet, responsible for the climate and sustainable cities program WWF France, the urgency is no longer to spare the various sensitivities. “The current trajectory is not good, he recalls. We are already seeing an average temperature rise of 1.1 ° C compared to the pre-industrial era a century and a half ago. At the current rate, the 2 ° C threshold will be exceeded around 2075. The IPCC's fifth assessment report was very clear on the fact that this + 2 ° C was a climatic point of no return. "
This new report comes out two months before the start of the COP24 climate negotiations scheduled for Poland.
The member countries of the UN must begin a process of revising their 2015 commitments, insufficient because of the promise of a world at 3 ° C in 2100. “If we want to stay in a world at 1.5 °, there is will have compulsory passage points, warns Pierre Cannet.
That in particular of carbon neutrality in 2050, that is to say the balance between the greenhouse gas emissions that our human activities will emit and what our planet is able to observe.
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