The Arctic shattered heat records in the past year as unusually warm air triggered massive melting of ice and snow and a late fall freeze, US government scientists said Tuesday.
The grim assessment came in the Arctic Report Card 2016, a peer-reviewed document by 61 scientists around the globe issued by the US National Oceanic and Atmospheric Administration (Noaa).
The Noaa report covers from October 2015 to September 2016, a period it said the Arctic’s average annual air temperature over land was the highest on record.
“The report card this year clearly shows a stronger and more pronounced signal of persistent warming than any previous year in our observational record” going back to 1900, Noaa Arctic Research Program director Jeremy Mathis told the American Geophysical Union conference in San Francisco, where the report was released.
The environment has steadily declined since scientists started doing the annual report card, now in its 11th year, co-author Donald Perovich said.
Warming twice as fast
The Arctic region is continuing to warm up more than twice as fast as the rest of the planet, which is also expected to mark its hottest year in modern times.
Climate scientists say the reasons for the rising heat include the burning of fossil fuels that emit heat-trapping gases into the atmosphere, southerly winds that pushed hot air from the mid-latitudes northward, as well as the El Nino ocean warming trend, which ended mid-year.
The Arctic’s annual air temperature over land was 3.5° C higher than in 1900, the report said.
The sea surface temperature in the peak summer month of August 2016 reached 5°C above the average for 1982-2010 in the Barents and Chukchi seas and off the east and west coasts of Greenland.
It was also 28% less than the average for 1981-2010 in October.
Scientists added a section to the report about noteworthy records set in October and November 2016, even though that extended beyond the report’s typical time span.
On thin ice
More of the ice that freezes in the Arctic winter is thin, made of only a single year’s worth of freeze rather than thicker, more resistant ice built up over multiple years.
In 1985, almost half (45%) of Arctic sea ice was called “multi-year ice.” Now, just 22% of the Arctic is covered in multi-year ice. The rest is first-year ice.
In Greenland, the ice sheet continued to shrink and lose mass as it has every year since 2002, when satellite measurements began. Melting also started early in Greenland last year, the second earliest in the 37-year record of observations, and close to the record set in 2012.
The springtime snow cover in the North American Arctic hit a record low in May, when it fell below 4 million square kilometres for the first time since satellite observations began in 1967.
This melting, combined with retreating sea ice, has allowed more sunlight to penetrate the ocean’s upper layers, stimulating widespread algae blooms.
The Arctic’s people and animals are also suffering from the climate changes.
The Arctic could be free of summer ice by the 2040s, Perovich said, adding that the changing temperatures are already affecting people who live in the region.