The Giec publishes this Monday the second part of its assessment report, to be seen as the synthesis, at the moment T, from tens of thousands of studies, of the state of scientific knowledge on climate change.
This second part focuses on the impacts of climate change and how to prepare for it.
In other words, this new report has looked at the issues of adaptation to climate change.
Of the 7.8 billion humans on Earth, "between 3.3 and 3.6 billion live in an environment very vulnerable to climate change", assesses, with "a high level of confidence", the Group of Experts intergovernmental on climate change (IPCC).
A high proportion of animal and plant species are too, he adds.
This is one of the many findings of the second part of its sixth climate assessment report published by the group of experts on Monday.
Since its creation in 1988 by the UN, this is the sixth time – and the first since 2014 – that the IPCC has tackled this titanic work which consists in synthesizing at the moment T the world's scientific knowledge on the climate change.
A first part, drawn up by group 1 and published on August 9, focused on the scientific aspects of the climate system and climate change and drew up the report of a climate crisis which is worsening everywhere and at unprecedented levels. .
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Two hundred and thirty-four authors from 66 countries participated in its development, based on 14,000 studies.
This is even more for this new report with 270 authors involved and 34,000 scientific studies cited.
This time, the IPCC looked at the consequences of climate change and ways to prepare for it.
A relationship that is not only written in the future
The conclusions that group 2 of the IPCC draws up in the 35 pages of the “summary for decision-makers” are not all written in the future tense.
“Since the fifth assessment report of 2015, a wider range of impacts can be attributed to climate change, specify the authors.
In other words, there is new knowledge to argue that climate change [these impacts] have caused or made them more likely.
“Many species are reaching their limits in their ability to adapt to climate change, and those that cannot adapt or move fast enough are at risk of extinction,” points out the IPCC.
Result: “the distribution of plants and animals across the globe is changing,
In many cases, these changes reduce nature's ability to provide the essential services we depend on to survive.
The IPCC cites, among these services, the protection of the coasts, the food supply, but also the regulation of the climate, via the role of carbon sinks, the oceans, the forests, the land capturing a large part of the CO2 that we emit. .
Other consequences already noted by the IPCC include the increased frequency and spread of diseases in wildlife, agriculture and humans.
The Covid-19 pandemic is the latest example.
The report also recalls that the seasons of forest fires are getting longer and that the areas burned are increasing, or that "about half of the world's population is currently experiencing serious water shortages at some point in the world. year, in part due to climate change and extreme weather events such as floods and droughts”.
Far from all being equal in the face of risks?
We are not all exposed in the same way to these climatic hazards.
This is another key message of this report: “The vulnerability of ecosystems and populations to climate change differs considerably between and within these regions, depending on the socio-economic development patterns of societies”, indicates the IPCC.
This vulnerability is higher in places where poverty, governance challenges, access to basic services and resources, violent conflicts are important, continue the authors of the report.
“Between 2010 and 2020, mortality rates from floods, droughts and storms were fifteen times higher in regions that are very vulnerable to the impacts of climate change compared to those that are the least,” continues the IPCC.
The group of experts identifies these "hotspots" of vulnerability in sub-Saharan Africa (West, Central and East), in South Asia, in Central and South America, but also in small island States, particularly exposed to the sea level rise or the Arctic.
These are regions that contribute little to global warming.
127 key risks identified with tenfold impacts the worse global warming gets
We could go on for a long time with this black picture painted by the IPCC.
Just a start?
Even by limiting global warming to 1.5°C [compared to the pre-industrial era], "the world is exposed to multiple inevitable climatic hazards in the next two decades", insists the IPCC.
And this trajectory of +1.5°C – the most ambitious of the Paris Climate Agreement – is still far from being the one we are heading towards, warns the UN on several occasions.
It is then another observation that Group 2 of the IPCC draws up with a high level of confidence: "for 127 key risks identified, the impacts assessed in the medium and long term are up to several times higher than those currently observed" .
This is particularly the case for biodiversity loss.
On Earth, "3 to 14% of the species assessed will probably face high risks of extinction at a global warming level of +1.5°C", recalls the IPCC.
The range increases from 3 to 18% at global warming of +2°C, from 3 to 29% at +3°C, from 3 to 39% at +4°C and from 3 to 48% at +5°C , list the report.
Another example: the increase in floods and their damage.
The latter will be 1.4 to 2 times higher in a world at +2°C compared to a world that has remained at +1.5°C and which would have done nothing to adapt to these risks, anticipates the Giec with, however, a medium level of confidence in this projection.
We go from 2.5 to 3.9 times more in a world at +3°C.
And at +4°C, “about 10% of the land area is expected to experience increases in extreme river flows, both high and low in the same location, which will complicate planning for water resource use” , advances the Giec, always with an average level of confidence.
“A terrible warning about the consequences of inaction”
The IPCC also mentions the pressures on agricultural production and access to food, the weakening of the soil, the increase in the indices of poor health and premature death in the list of these impacts of climate change which will increase tenfold the more warming intensifies.
The group of experts also emphasizes the risks incurred by populations living in coastal areas, while 60% of the world's population now live less than 100 km from the coast.
“The coastal population exposed to a 100-year coastal flood is expected to increase by 20% if the global mean sea level increases by 0.15 m compared to the level of 2020, estimates the IPCC.
This share doubles if the elevation is 0.75 m and triples if it is 1.4 m.
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In short, it is a picture just as black as last August that the IPCC paints in this second part of its sixth evaluation report.
“This report is a terrible warning about the consequences of inaction, insists the South Korean economist Hoesung Lee, president of the IPCC.
Our actions today will shape how humans and nature can adapt to global warming and the increase in climate hazards that it comes with.
This new report is not limited only to these worrying projections but also devotes a large part to adaptation.
Or the solutions to be implemented, right now, to adapt to climate change.
This will be the subject of a second article to come on Monday.
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