Ice in the Arctic Ocean melted to its second-lowest level on record this year, scientists announced on Monday, in yet another sign of how global warming is rapidly transforming the polar region.
Satellites recorded this year’s sea ice minimum at 3.74 million square km (1.4 million square miles) on September 15, only the second time the ice has been measured below 4 million square km (1.5 million square miles) in 40 years of record-keeping, according to researchers at the United States’s National Snow and Ice Data Center.
“It’s been a crazy year up north, with sea ice at a near-record low… heat waves in Siberia, and massive forest fires,” said Mark Serreze, director of the NSIDC.
“The year 2020 will stand as an exclamation point on the downward trend in Arctic sea ice extent. We are headed towards a seasonally ice-free Arctic Ocean, and this year is another nail in the coffin.”
This year’s melt is second only to 2012, when the ice shrank to 3.4 million square km (1.3 million square miles) following a late-season cyclonic storm.
Arctic sea ice reaches its low point in September and its high in March after the winter, and in the 1980s, the ice cover was about 2.7 million square km (1 million square miles) bigger than the current summer levels.
This year’s decline was especially fast between August 31 and September 5, because of pulses of warm air from a heatwave in Siberia, according to the NSIDC. The rate of ice loss during those six days was faster than during any other year on record.
Temperatures in the Siberian Arctic were 8 to 10 degrees Celsius (14 to 18 degrees Fahrenheit) above normal for much of the year, and another team of scientists found in July that the Siberian heatwave would have been all but impossible without human-caused climate change.
Studies show that the warming of the Arctic and the melting of sea ice change weather further south, by altering the jet stream and other waves that move weather systems.
As the Arctic sea ice vanishes, it leaves patches of dark water open. Those dark waters absorb solar radiation rather than reflecting it back out of the atmosphere, a process that amplifies warming and helps to explain why Arctic temperatures have risen more than twice as fast as the rest of the world over the last 30 years.
The loss of sea ice also threatens Arctic wildlife, from polar bears and seals to plankton and algae, said Tom Foreman, a polar wildlife expert and Arctic guide.
“The numbers that we’re getting in terms of extent of sea ice decrease each year put us pretty much on red alert in terms of the level of worry that we have, our concern for the stability of this environment,” Foreman said.
The same warming that is opening summertime Arctic waters is also eating away at the ice sheets covering Arctic lands in Canada and Greenland. The faster those ice sheets melt into the surrounding ocean, the faster sea levels will rise worldwide.
“The rapid disappearance of sea ice is a sobering indicator of how closely our planet is circling the drain,” Greenpeace Nordic Oceans campaigner Laura Meller said in a statement.
“Over the past decades we have lost two-thirds of the volume of the Arctic sea ice, and as the Arctic melts the ocean will absorb more heat and all of us will be more exposed to the devastating effects of climate breakdown,” she later told the AFP news agency from a ship on the edge of the sea ice.
“What we are seeing here in the Arctic is really the opening up of a new ocean on top of the world, which means that we need to be protecting the area.”
The 2015 landmark Paris climate deal enjoins nations to limit global temperature rises to “well below” two degrees Celsius (3.6 degrees Fahrenheit) through a rapid and sweeping reduction in greenhouse gas emissions.
But emissions have continued to rise despite the deal, and several analyses have warned that without a thoroughly re-tooled global economy prioritising green growth, the pollutions savings due to the COVID-19 pandemic will have an insignificant mitigating effect on climate change.