High temperatures in North Pole The ice covering the Arctic Ocean has shrunk this year to its second lowest level in four decades, scientists announced, in another sign of how the climate crisis is rapidly changing the region.

Satellites recorded the minimum sea ice for this year at 3.74 million square kilometers on September 15, researchers at the National Ice and Snow Data Center said, which is only the second time that ice has been measured below 4 million square kilometers in 40 years of record-keeping.

“It’s somewhat devastating to have such a consistently low sea ice.” Toila Moon, a glaciologist at the Research Center in Boulder, Colorado, said, “But unfortunately, this is not surprising.”

The record low of 3.41 million square kilometers, reached in 2012 after a late-season hurricane storm smashed the remaining ice, not much less than what researchers see today.

The decline this year was particularly rapid between August 31 and September 5, thanks to pulses of warm air emanating from the Siberian heatwave, according to NSIDC. The rate of ice loss during those six days was faster than in any other year on record. Another team of scientists found in July that a heatwave in Siberia was impossible without human-induced climate change.

As Arctic sea ice disappears, it leaves patches of dark water open. Those dark waters absorb solar radiation instead of reflecting it back out of the atmosphere, a process that amplifies warming and helps explain why temperatures in the Arctic have risen more than twice as fast as the rest of the world over the past 30 years.

Tom Furman, arctic wildlife expert and Arctic guide, said the loss of sea ice also threatens Arctic wildlife, from polar bears and seals to plankton and algae.

“The numbers we get in terms of how much sea ice is diminishing each year put us on high alert in terms of the level of anxiety that we have and our concern for the stability of this environment,” said Furman.

The same warming that began in the summer in Arctic waters is also eroding in the ice sheets covering the Arctic lands of Canada and Greenland. The faster those ocean ice sheets melted, the higher the sea level around the world.

Given that a warmer Arctic could affect weather patterns around the world, Moon said the world should not wait for a new low level of sea ice before taking action to curb climate change.

“We have to work hard to make variations in our emissions of pollutants so that we don’t see a lot of records created in the future,” Moon said.