After the facts, the effects and the means to adapt to them. While the first part of the sixth report of the Intergovernmental Panel on Climate Change (IPCC) focused on climate change, the second part, published on Monday February 28, details the consequences of this global warming on human societies and ecosystems. It also reviews ways to adapt to it.
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“This report is a dire warning about the consequences of inactionwarned Hoesung Lee, the president of the IPCC, in a press release. It shows that climate change is a serious and growing threat to our well-being and the health of this planet. Our actions today will determine how humanity and nature adapt to growing climate risks.” A third part, devoted to the means of limiting this warming, will be published at the beginning of April.
Floods, agricultural losses, heat waves… Here is what to remember from this reference document, drawn up by 270 scientists from 67 countries.
Global warming is already doing damage and the situation will get worse
Global warming is not a problem of the future, but a reality already observed with +1.09°C compared to the pre-industrial era: more intense and more frequent heat waves, increase in forest fires and precipitation, sea level rise, ocean acidification… “Human-induced climate change (…) is having a widespread negative impact and has caused loss and damage to nature and humanity, beyond any natural variation”write the authors of the report in the summary for decision makers, a short version discussed and approved with representatives of all member countries of the IPCC. “Increasing weather and climate extremes have had irreversible impacts, pushing human and natural systems beyond their adaptive limit”they continue.
On our health. Climate change is already a health problem. “In all regions, extreme heat events caused deaths”, can we read in the report. The document also highlights the increase in respiratory diseases due to forest fires, or pathologies related to food, water and animals. The report cites, for example, an increase in cholera, caused by increased rains and floods. In some regions, increasing temperatures and extreme events are also affecting the Mental Health.
on our societies. At the collective level, climate change has “reduces food security and access to water” for millions of people in Africa, Asia, Central and South America, small islands and the Arctic, leading to malnutrition problems. “Climate hazards reduce agricultural production, and CO2 stimulates photosynthesis but reduces the nutritional quality of crops”explains Delphine Deryng, researcher at the University of Humboldt (Berlin) and author of the report.
In cities, global warming has aggravated air pollution and limited the functioning of key infrastructures, such as transport, energy or water supply. On the economic plan, “damage has been detected in climate-sensitive sectors, with regional effects on agriculture, forestry, fisheries, energy, tourism and outdoor labor productivity”.
On ecosystems. Animals, plants and natural spaces are at the forefront, with “substantial damage and increasingly irreversible losses to terrestrial, freshwater, coastal and marine ecosystems”. Half of the species monitored move towards the poles or climb in altitude to escape the increase in temperature. Heat waves cause high mortality and irreversible changes are taking shape with the retreat of glaciers, the melting of permafrost in the Arctic regions or the acidification of the oceans. “The extent and magnitude of climate change impacts are greater than estimated in previous reports”the authors point out.
In the coming years. These effects, which differ according to regions and according to socio-economic categories, will worsen and intensify with each additional tenth of a degree. The risks can combine with each other – a drought and a heat wave – to create cascading consequences – a forest fire – which will be more complicated to deal with. “We’re only just starting”warns Gonéri Le Cozannet, researcher at the Bureau of Geological and Mining Research (BRGM) and one of the authors of the text.
The report distinguishes two periods, the short term (2021-2040) and the medium-long term (2040-2100). For the first, the stakes are partly already cast since we have already emitted too many greenhouse gases. “Global warming, reaching 1.5°C, will cause an inevitable increase in multiple climate risks”says the report.
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For the second, it will depend on the level of warming. If we take the example of floods, the damage will be, compared to a warming of 1.5°C, up to 2 times greater for 2°C, and up to 4 times greater for a warming of 4 °C. “About one billion people could be threatened by coastal climate hazards, in the medium term and in all scenarios” greenhouse gas emissions, notes the IPCC. At present, the promises of the States (which have not yet been kept) are leading us towards a warming of 2.7°C.
Adaptation can reduce risks, provided that the level of global warming is limited
Faced with this situation, humanity can partly adapt. “If we engage much more strongly than currently, we can manage to avoid many of the serious consequences”, explains Wolfgang Cramer, CNRS research director at the Mediterranean Institute of Biodiversity and Marine and Continental Ecology (IMBE) and one of the authors of the report. Three adaptation scenarios are reviewed: limited, incomplete and pro-active. This can significantly reduce the risks.
While it welcomes some progress, the report notes above all the existence of a “gap between the current level of adaptation and the levels necessary to (…) reduce climate risks”. Most measurements are “fragmented, small-scale, incremental, sector-specific, designed to respond to current consequences or near-term risks, and focused on planning rather than implementation”. The risk of maladaptation is also present. For the IPCC, solutions “integrated, multisectoral, which also address social inequalities” are more efficient. “It is now clear that minor, incremental, reactive or incremental changes will not be enough”write the experts in the frequently asked questions that complete the report.
“As global warming increases, loss and damage will increase and more and more human or natural systems will reach their limits of adaptation”warn scientists, pointing out that some ecosystems, such as corals, have already passed the point of no return. “Europe is much less vulnerable than Africa and yet, even on this continent, adaptation alone is not sufficient to limit the risks beyond 1.5°C of warming”explains Gonéri Le Cozannet, who participated in writing the chapter devoted to the Old Continent.
Mitigation, ie the reduction of greenhouse gas emissions resulting from our lifestyles (transport, food, housing) and drivers of global warming, is therefore essential. “This report clearly shows that ensuring climate-resilient development [qui intègre des mesures d’adaptation et d’atténuation équitables pour tous] is already difficult at the current level of warming, writes the IPCC. It will be even more complicated if it exceeds 1.5°C. In some areas, it will be impossible if it exceeds 2°C.”
Protecting nature is essential for the future of our societies
IPCC scientists insist on the importance of protecting nature, threatened by human activities. “Safeguarding biodiversity and ecosystems is fundamental for climate-resilient development”, they write. They emphasize that these natural systems play a role in limiting climate change and adapting to its effects. According to their estimates, based on published scientific literature, this requires the effective protection of 30 to 50% of land, waterways and oceans.
Otherwise, these ecosystems could on the contrary play a negative role. Their degradation and destruction “is also a source of greenhouse gas emissions and this is likely to be aggravated by the consequences of climate change, such as droughts or forest fires”. And between 3 and 14% of terrestrial species are threatened with extinction even if global warming is limited to +1.5°C.
Immediate action is needed
This report draws up an acknowledgment of failure. “Current and past trends (emissions, development and climate change) have not allowed progress towards global development resilient to climate change”write its authors. “The scientific evidence is unequivocal: climate change is a threat to the well-being of humanity and the health of the planet, stress the scientists at the conclusion of the summary for decision makers. Any delay in implementing concerted, comprehensive and anticipated action on adaptation and mitigation will cause us to miss the short window of opportunity, which is fast closing, to ensure a livable and sustainable future for all. .”