Climate scientists and activists responded with alarm Thursday to reporting that this is the latest date in recorded history that "the main nursery of Arctic sea ice in Siberia has yet to start freezing," another example of the present-day consequences of human-caused global heating.

According to the Guardian, "The delayed annual freeze in the Laptev Sea has been caused by freakishly protracted warmth in northern Russia and the intrusion of Atlantic waters, say climate scientists who warn of possible knock-on effects across the polar region."

"The lack of freeze-up so far this fall is unprecedented in the Siberian Arctic region," Zachary Labe, a postdoctoral researcher at Colorado State University, told the newspaper, adding that the current conditions are in line with scientists' expectations about the consequences of anthropogenic climate change.

"2020 is another year that is consistent with a rapidly changing Arctic," added Labe, who also shared a series of related graphics on Twitter. "Without a systematic reduction in greenhouse gases, the likelihood of our first 'ice-free' summer will continue to increase by the mid-21st century."

As the Guardian detailed:

The Laptev Sea is known as the birthplace of ice, which forms along the coast there in early winter, then drifts westward carrying nutrients across the Arctic, before breaking up in the spring in the Fram Strait between Greenland and Svalbard. If ice forms late in the Laptev, it will be thinner and thus more likely to melt before it reaches the Fram Strait. This could mean fewer nutrients for Arctic plankton, which will then have a reduced capacity to draw down carbon dioxide from the atmosphere.

More open sea also means more turbulence in the upper layer of the Arctic ocean, which draws up more warm water from the depths.

In a series of tweets about the reporting, climate scientist Peter Kalmus declared, "Goodbye to the delicate sheet of ice at the top of our planet."

Kalmus was far from alone in expressing concern and frustration over the conditions in the Arctic and pointing to the new record as just the latest evidence that policymakers must urgently address the climate crisis.

"This is a frightening milestone," Food & Water Watch tweeted about the lack of ice in the Laptev Sea. "Our leaders must act to curb and mitigate climate change."

The Green Party in the United Kingdom also shared the report and warned that "we're breaking the wrong records."

"Time is running out," tweeted former congressional candidate Skylar D. Hurwitz, calling on Americans to vote for Democratic presidential candidate Joe Biden. Although the former vice president remains under pressure from progressives to embrace bolder policies, the contrast between his positions and those of President Donald Trump has won him widespread support from climate experts and advocates.

The latest climate crisis record comes after Arctic sea ice shrank to the second-lowest documented extent last month, which the National Oceanic and Atmospheric Administration found was the hottest September ever recorded. Global scientists warned earlier this month that 2020 is on track to be the warmest year on record.