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Global warming is increasing the temperature of the Arctic at a record pace, reducing ice in the region and causing major environmental changes worldwide, a US government agency said Tuesday. The year 2018 is the second warmest in the Arctic since it began recording temperatures in 1900, according to a report by the National Oceanic and Atmospheric Administration (NOAA), which warned that the warming had resulted in "profound changes" in the ecosystem.
The agency reported that only the year 2016 had been historically warmer than in 2018, the year in which the Arctic recorded a temperature of 17 ° C above the average of last three decades, with warming twice as fast as the global average.
is clear: the last five years have been the hottest ever recorded, according to NOAA, which coordinated this historical report written by more than 80 scientists from 12 countries.
"The Arctic is going through an unprecedented transition period in the history of humanity," said Emily Osborne of the University of California at Berkeley in a report on the effects of climate change. NOAA Arctic Research Program
In the Arctic Ocean, ice is formed from September to March, but this range is decreasing inexorably over the years. The ice is thinner, younger and covers a smaller part of the ocean.
It is a vicious circle: the youngest ice is more fragile and melts in early spring. And less ice means less sun reflection: the ocean absorbs more energy and heats up a bit more.
In the past 12 years, the ice cover has been the most fragile. Bering between Russia and Alaska as well as in 2017-2018. In general, the strongest winter arrives in February, but this year the ice melted this month. "This is an important piece of information this year," said Donald Perovich, a professor at Dartmouth College, "the loss of a region the size of Idaho," an area of of about 215 000 km 2 in February.
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In contrast, the acceleration of the melting of the Greenland ice cover stabilized, according to the NOAA
The US agency has extensive data. Its satellites travel the Arctic 28 times a day and provide the most accurate readings possible on the ice and oceans. It is also based on a network of scientists, sensors and buoys.
According to this agency, the six rivers of Eurasia that have flowed into the Arctic Ocean have dumped 25% more water in the summer than in the 1980s. [19659002]
"The agency noted that the continued warming of the atmosphere and oceans in the Arctic is causing major changes to the environmental system," the agency said.
Reindeer populations in the wild tundra have declined since the middle of the month. 1990s.
Only two of the 22 herds monitored did not decline. Five have lost more than 90% of their members in Alaska and Canada and "show no signs of recovery"
"Some herds have populations at the lowest level ever recorded," warns the agency. Most are officially clbadified as rare or endangered.
The probable cause is the enlargement of the summer and its ills for the animals, well equipped for the winter but not for the hot season because of parasites, fleas and diseases.
On the other hand, warming helps toxic red algae (microscopic plankton or larger algae) to conquer new territories as they penetrate into increasingly cold Arctic waters, where fish and crustaceans can poison. "The data collected over the last decade clearly show that there are many toxic algal species in the Arctic food chain at unsafe levels, and it is very likely that this problem persists and remains unclear. "worsens in the future," according to the NOAA
Arctic Warming is also changing the jet stream that has consequences for midlatitudes, well below the pole. But if this barrier "softens", the cold air mbades descend and bring warm air up. According to the report, this contributes to the proliferation of extreme weather events, such as heatwaves in the western United States and exceptional snowstorms on the east coast.
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