• Where is the science in the knowledge of climate systems and climate change?

    This is the question that the Intergovernmental Panel on Climate Change (IPCC) has looked into, as it has done five times since its creation.

  • This report, which compiled 14,000 scientific papers, will be published on August 9.

    And this is only the first part of the evaluation report that the IPCC draws up every seven years from now on.

  • Before the publication of this first part, it still remains to have the “summary for decision-makers” approved by 195 states. It is this work that the IPCC opened on Monday and which will last until August 6. With the risk that the work of the IPCC will be watered down?

On August 9, the Intergovernmental Panel on Climate Change (IPCC) will publish the first part of its sixth assessment report. A highly anticipated job, since it is about providing the most recent scientific understanding of the climate system and climate change. Before that, it remains to have the governments of the 195 States Parties to the United Nations Framework Convention on Climate Change (UNCCD) approved, this report and the “summary for decision makers”. A summary that accompanies each release of the IPCC report and whose drafting may be the subject of intense scientific controversy.

The IPCC launched this work, this Monday and until August 6, by opening a virtual plenary session (Covid-19 requires) bringing together the scientists involved in the report and the delegations of these 195 States.

What's going to come out of it?

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 takes stock.

What is the IPCC again?

The Intergovernmental Panel on Climate Change was established in 1988, at a time when there was awareness of the risks of too much greenhouse gas accumulation in the atmosphere.

The IPCC is both an initiative of scientists aware of being faced with an important problem to be publicized and a political decision, this group of experts being placed under the responsibility of the World Meteorological Organization (WMO) and the United Nations Program. United for the Environment (UNEP).

His mission ?

Evaluate without bias and in a methodical, clear and objective manner, the information necessary to better understand the risks associated with human-induced global warming.

What exactly will the IPCC publish on August 9?

The IPCC draws up two types of reports.

On the one hand, there are special reports commissioned by the UN on specific subjects.

For example, the IPCC has published a series of three since 2018: on the challenges of global warming stabilized at 1.5 ° C, on the oceans and the cryosphere and on soil conservation.

The other major mission of the IPCC is to come out of the evaluation reports. Since its inception, it has published five. "The last one dates from November 2014 and the penultimate one from 2007", specifies Sandrine Mathy, CNRS researcher at the Applied Economics Laboratory in Grenoble. This is therefore the sixth edition that the IPCC is about to release. August 9 precisely? Not quite. "These evaluation reports include three parts, corresponding to the three working groups of the IPCC," resumes Sandrine Mathy. The first consists of a major update of scientific knowledge on climate change. The second deals with the impacts and adaptations to climate change. And the last one focuses on the solutions to be provided. It is only the first part that the IPCC will be released on August 9th. "The other two will follow,in February and next March, says Clément Sénéchal, climate spokesperson for Greenpeace France. The final report should be released in October 2022. "

How did the IPCC work on this first part?

“The IPCC does not produce new scientific knowledge, insists Sandrine Mathy.

But it synthesizes existing work by focusing only on articles published in peer-reviewed scientific journals.

"A colossal work in which 234 main authors participated and in which 14,000 scientific articles are referenced," specifies the IPCC.

This first part should show notable differences with the last edition, which dates, as we have said, from seven years ago. “What is certain is that climate science has deepened and extended since 2014, thanks in particular to the proliferation of studies,” notes Clément Sénéchal. This is the case, for example, with work on attribution, a branch of climatology that studies and quantifies the mechanisms by which human activities lead to climate change. The Fifth Assessment Report spoke of a “clear” influence of human activities on climate systems. The update could leave less doubt. In January, a study published in the journal

Nature Climate Change

, by an international team of scientists, concluded that "almost all of the global warming observed since the beginning of the industrial era has been caused by human activities".

"The IPCC should also focus on the more detailed understanding that scientists have of the regional impacts of climate change", continues Clément Sénéchal.

Recent research has shown that extreme events would have been impossible without global warming.

This is particularly the case for the 2020 heat wave in Siberia and the 2016 heat wave in Asia.

Can this first part be watered down by the 195 states in the coming days?

Even before Monday, the full report - of several thousand pages - and its summary for decision-makers - reduced to a few dozen - have already been the subject of first round trips. "Both with reviewers [other scientific experts] but also by countries," explains Sandrine Mathy. These exchanges gave rise to tens of thousands of comments to which the main authors had to respond. "So Monday, we entered the final sprint with a view to agreeing on the final formulation of this summary for decision-makers", continues Lola Vallejo, director of the climate program of the Institute for Sustainable Development and International Relations (Iddri). With the risk that some States will try to rewrite this summary to reduce its scope?

"These exchanges between the scientists involved in the report and the delegations of the 195 States are very structured, so that what will be retained in the final version of the summary is very scientifically robust," replies Lola Vallejo. The stake of this plenary session is more, for the IPCC, to ensure the good understanding of its report by the governments, and therefore of its appropriation. This should not be yet another scientific report, but rather an inventory of climate science carried by States. "

Clément Sénéchal does not believe in diplomatic passes on this first part of the report either.

"We are on hard science, difficult to discuss it politically," he believes.

The negotiations are more likely to be tougher on the other two parts of the report, in particular the third, which addresses solutions to reduce greenhouse gas emissions.

A much more sensitive subject for States, between those who want to accelerate the transition, those who are late, those who do not want to be singled out… ”

Of the three parts of the evaluation report, is the first the most important?

"The three are complementary and as important as each other", slips Lola Vallejo. However, this first report, by updating the state of scientific knowledge on climate change, “can be seen as the foundation on which the other two parties will rely, on understanding the risks of climate change. and the answers to be provided ”, considers both the IDDRI expert and Clément Sénéchal to Greenpeace. The latter sees even further, recalling the diplomatic summits to come by the end of the year. From the G20 next October in Italy - which will bring together the world's richest and most emitting countries - to COP26 in Glasgow, from November 1 to 12, during which states will have to review their climate ambitions.

This report, published on August 9, should therefore sound like yet another reminder to act, “even though we can see that this summer is marked by a series of global catastrophes, from the heat dome in Canada to the exceptional precipitation over part of the country. 'Europe and Asia.

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