WASHINGTON • Every year for the past 15 years, environmental scientists working under the aegis of a US government agency issue a report on the state of the Arctic, and Tuesday's edition confirms an alarming trend: The North Pole is heating up twice as fast as the rest of the planet.
The year 2020 did not beat the record set in 2012, but it got very close.
The sea ice floating in the Arctic ocean melts in summer and freezes again in winter. The problem is that each year, it is melting a bit more in the warm weather and refreezing a bit less.
Scientists now get reliable data as satellites have been photographing and measuring the Arctic non-stop since 1979. And there is no room for doubt about the region's melting pattern.
The late summer thaw in 2020 was the second worst year on record after 2012. Compared with its highest historical level, half of the sea ice is now gone. The ice is thinner, younger and more fragile.
The Arctic Report Card 2020, released by the National Oceanographic and Atmospheric Administration on Tuesday, provides a wealth of information that illustrates the complexity of the Arctic climate system.
The climate in the rest of the world - wind and currents - affects what happens at the North Pole while the South Pole is comparatively more isolated.
Alaska's North Slope experienced its coldest February in 30 years and it was also colder than usual in Svalbard, Norway.
But Siberia set heat records, with temperatures 3-5 deg C above normal, and the region suffered terrible wildfires in spring.
The air temperature at the surface of the Arctic over the course of 2019-2020 was 1.9 deg C higher than the average for the period in 1981-2010, making it the second hottest year on record since 1900.
The phenomenon of "Arctic amplification", which causes this region to heat up faster than other parts of the world, is in full force.
The Arctic ocean is also heating up: In August, the water was between 1 and 3 deg C hotter at the surface than the average for 1982-2010.
Here, too, events are linked and fuel each other. When ice melts and exposes the ocean, the water absorbs more heat from the sun, which in turn worsens the melting of the sea ice, although this time from underneath.
"One of the things that's important to realise about the Arctic is it's a system. It's a system of interconnected components," said Dartmouth University's professor of engineering Donald Perovich, co-author of the sea ice chapter in the report. "You can change one thing, (and) those changes cascade through the whole system."
Sea ice is both an indicator and amplifier of global warming. Its melting does not contribute directly to rising sea levels, as this ice is already in the water. But it does contribute indirectly by heating up the water.
Models forecast that there will no longer be any sea ice in summer in the Arctic starting between 2040 and 2060.
Back in the first edition of this report in 2006, researchers were still not sure of the Arctic heating trend. They expressed doubt that permafrost - soil that is frozen year round - could melt in the north of Alaska.
Now, those same researchers say "it is anticipated that progressive deep thawing of permafrost in this region may begin in 30-40 years".