Europe 1 with AFP 10:52 am, 06 September 2023

According to the European Copernicus Observatory, 2023 is likely to be the hottest year on record. Average global temperatures have been particularly high this summer, including in the southern hemisphere, despite being in the middle of the austral winter. The average temperature recorded during the last 3 months is 16.77 degrees.

The summer (June-July-August) saw the highest average global temperatures ever measured, announced Wednesday the European observatory Copernicus, for which 2023 will probably be the hottest year in history. Heat waves, droughts, floods or fires hit Asia, Europe and North America during this period, in dramatic and often unprecedented proportions, with their cost in human lives and damage to economies and the environment.

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"The collapse has begun"

The southern hemisphere, where many heat records were broken in the middle of the austral winter, was not spared. "The June-July-August 2023 season," which corresponds to summer in the Northern Hemisphere, where the vast majority of the world's population lives, "was by far the hottest ever recorded in the world, with a global average temperature of 16.77°C," Copernicus said. This is 0.66°C above the averages of the period 1991-2020, already marked by the rise in global average temperatures due to global warming caused by human activity. And well above - about 2 tenths - the previous record of 2019.

"Climate collapse has begun," UN chief António Guterres said in a statement. July was the hottest month ever measured, August 2023 is now the 2nd, says Copernicus. And over the first eight months of the year, the average global temperature is "only 0.01 ° C behind 2016, the hottest year ever measured". But this record hangs by a thread, given seasonal forecasts and the return in power in the Pacific of the El Niño climate phenomenon, synonymous with additional warming.

And "given the excess heat at the surface of the oceans, it is likely that 2023 will be the warmest year (...) that humanity has known," Samantha Burgess, deputy head of Copernicus' climate change service (C3S), told AFP. The Copernicus database goes back as far as 1940, but can be compared to the climates of past millennia, established through tree rings or ice cores and synthesized in the latest report of the UN climate panel (IPCC).

On this basis, "the three months we have just experienced are the warmest in about 120,000 years, that is, since the beginning of human history," says Burgess.

Overheating of the oceans

Despite three successive years of La Niña, the opposite El Niño phenomenon that partly masked the warming, the years 2015-2022 have already been the warmest ever measured. The overheating of the world's seas, which continue to absorb 90% of the excess heat caused by human activity since the industrial era, plays a major role in the phenomenon. Since April, their average surface temperature has been changing to unprecedented levels of heat.

"From July 31 to August 31", it even "exceeded each day the previous record of March 2016", notes Copernicus, reaching the unprecedented symbolic bar of 21 ° C, very clearly above all archives. "The warming of the oceans leads to warming of the atmosphere and an increase in humidity, which causes more intense precipitation and an increase in the energy available for tropical cyclones," says Samantha Burgess.

Overheating also affects biodiversity: "there are fewer nutrients in the ocean (..) and less oxygen" which threatens the survival of fauna and flora, adds the scientist, who also cites coral bleaching, harmful algal blooms or "the potential collapse of reproductive cycles". "Temperatures will continue to rise until we turn off the emissions tap," mainly from the burning of coal, oil and gas, said Samantha Burgess three months before COP28 in Dubai.

This United Nations Climate Conference, where a fierce battle over the end of fossil fuels is announced, is supposed to put humanity back on the trajectory of the Paris Agreement: limiting warming to well below 2 ° C and if possible to 1.5 ° C compared to the pre-industrial era.