The oceans, way of becoming a nightmare for man

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The same oceans that contributed to the evolution of the human being will end up contributing misery on a global scale if the CO2 pollution that is damaging the marine environment is not reduced, according to the draft of a UN report obtained by the AFP that will be presented on 25 September in Monaco.

The destructive changes that are under way can make fish stocks decline sharply , multiply by one thousand the damages caused by cyclones (also known as superstorms) and leave hundreds of millions of people homeless due to sea level rise, according to the "special report" on oceans and icy areas (cryosphere) of the Intergovernmental Panel on Climate Change (IPCC).

Melting glaciers will first give too much water and then very little to billions of people who depend on them, according to this work.In addition, the permafrost surface of the northern hemisphere could melt between 30 and 99% and record an explosion of emissions of CO2 and methane, further accelerating global warming.

Governments will study the report in Monaco , while world leaders attend a climate summit on September 23 in New York, convened by UN Secretary General Antonio Guterres, to obtain greater national commitments in the fight against warming.

Insufficient promises

But according to several experts, the offers of the world's largest emitting countries - China, the United States, India and those of the EU - may not be up to the climatic urgency. The four - which represent almost 60% of global emissions from fossil fuels - are exposed to devastating impacts related to oceans and glaciers, but none of them seems prepared to announce ambitious goals.

The American president, Donald Trump, wants to take his country out of the Paris Agreement and has shattered the climate policies of his predecessor, Barack Obama. India rapidly develops solar energy, while continuing to build coal plants. The European Union strives for a goal of zero net emissions, but several Member States are reluctant.

China - which emits almost as much CO2 as the United States, the EU and India together - is also sending mixed signals. "Beijing has less and less eyes on environmental issues, especially on climate change," according to Li Shuo, China's climate policy analyst at Greenpeace International.

The resurgence of domestic coal plants and a relaxation of air pollution regulations suggest that China is primarily concerned about the economic slowdown and its trade war with the United States.

Towards irreversible changes

And yet all these nations face many of the threats underlined in the IPCC report, which can lead to "irreversible" changes.

For example, Shanghai, Ningbo, Taizhou and another half a dozen large coastal cities in China are very vulnerable to sea level rise, which is expected to reach one meter compared to the end of the 20th century if emissions are not reduced.

Millionaire efforts in the United States to protect New York, Miami and other exposed cities could become ineffective, experts say.

"There is this widespread idea in the United States now promoted by techno-optimists who believe we can design a way out of the problem," according to Michael Mann, director of the Earth System Science Center at the State University of Pennsylvania.

"But the United States is not prepared for the rise of one meter in 2100," he told AFP. "Just look at the consequences of cyclones Sandy, Katrina, in Houston or Puerto Rico."

Extreme phenomena every year

In 2050, many megacities located at low altitude and small island-nations will experience annual "extreme events" related to sea level, even if the most optimistic emission reduction scenarios were given, according to the report.

In 2100, annual damage due to flooding will be multiplied by a range of 100 to 1,000, according to the report summary.

Even if the world manages to limit warming to 2 ° C, the level of the oceans will rise sufficiently to displace 280 million people as early as 2100, although some experts anticipate that this will happen later.

"Even if it's 100 or 50 million, it's still a big problem and a lot of human misery," according to Ben Strauss, president of Climate Central, a research group in the United States, which highlights the "political instability levels already imply. relatively low current migrations. "

The global average temperature rose 1 ° C since the end of the 19th century and is on the way to increasing another two or three degrees at the end of the century. The Paris Agreement advocates limiting the climb to less than 2 ° C.

The rise in sea level in the 21st century "could exceed several centimeters per year," more than a hundred times than current levels, according to the report.

Marine heat waves

The oceans absorb a quarter of CO2 emissions, as well as more than 90% of the additional heat generated by greenhouse gas emissions since 1970.

Without this marine sponge, the heat on Earth would already be unbearable for the species.

But this action has a cost: acidification is altering the ocean's food chain and marine heat waves are creating vast dead zones.

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