Arctic sea ice plunged to a record low for the month of May, and now lies in a more brittle, fragile state than normal for this time of year, just as the height of the summer melt season gets underway.
According to the National Snow and Ice Data Center (NSIDC) in Boulder, Colorado, sea ice extent across the Arctic was 4.63 million square miles, which was an astonishing 224,000 square miles below the previous record low for the month of May, set in 2004.
Compared to the 1981-2010 average, sea ice extent was a whopping 537,000 square miles below average.
To put this another way, this means that the Arctic was missing a chunk of sea ice that was twice the size of the state of Texas.
“I think people have a hard time getting a grasp on how big a loss this is," NSIDC director Mark Serreze told Mashable in an interview. “This is a lot of real estate.”
The sea ice record occurred after record lows were also set in January, February and April, following a record warm winter throughout large parts of the Arctic that surprised even veteran climate scientists.
"We’re losing ice in all seasons now. And what happened, why we are where we are for this May, so very low, is very clearly a reflection of how absurdly warm it was over the Arctic all winter and into the spring,” he said.
In a press release on Tuesday, the NSIDC said that "an unusually early retreat" of sea ice cover in the Beaufort Sea to the north of Alaska, and "pulses of warm air entering the Arctic from eastern Siberia and northernmost Europe" helped prime the Arctic for the record low.
Regarding the prospects for setting an all-time record sea ice minimum at the end of the summer, Serreze told Mashable, "We are starting off definitely on a bad footing here.”
Every day in May set a daily sea ice record low, the NSIDC reported, with daily sea ice extents tracking about 232,000 square miles below any previous year in the 38-year satellite record. While the satellite record dates back to 1979, other records from submarines, indigenous peoples' knowledge and clues found in glacial ice cores and other sources point to the sea ice cover likely at its smallest and thinnest state in human history.
Importantly for what the May record could mean for the summer sea ice minimum coming up in September, the NSIDC found that daily sea ice extents were two to four weeks ahead of the levels seen in 2012, when the existing September sea ice minimum was recorded.
Comparing May 2016 with May 2012 shows a stark difference, with last month averaging more than 386,000 square miles below the extent observed in May 2012.
That doesn't necessarily mean that the 2016 sea ice minimum will set a new record, Serreze says, though it does increase the odds of such an outcome.
According to Serreze, a rule of thumb in sea ice forecasting holds that the earlier the sea ice melt season starts, the lower the summer sea ice minimum is likely to be. This is because as the reflective, brightly colored sea ice gives way to dark open ocean water, the ocean absorbs more incoming heat, and causes the water to warm up.
This in turn raises overlying air temperatures, helping to melt more ice and continuing the feedback loop known to scientists as Arctic amplification.
This is part of the reason why the Arctic is, on average, warming twice as fast as the rest of the globe.
Right now, sea ice cover is unusually small and thin, which means it's more susceptible to melting under the right weather conditions.
However, the rule of thumb does not always hold true or prove to be exact, since summer weather patterns will play a big role in moving the ice cover around — either encouraging some of it to remain intact or instigating a more rapid melt if sunny, mild weather prevails.
The NSIDC reported on Tuesday that sea ice extent remains below average in the Kara and Barents seas, which continues a pattern seen last winter through this spring.
Image: NASA/Modis via nsidc
Sea ice is also below average in the Bering Sea and East Greenland Sea. And in the Beaufort Sea to the north of Alaska "large open water areas have formed near the coast and ice to the north is strongly fragmented due to wind-driven divergence," the NSIDC said in a statement.
"The opening began in February, continued through March, and greatly expanded in April," the NSIDC said.
Air temperatures near the surface during May were 4 to 5 degrees Fahrenheit above average across most of the Arctic Ocean, with even higher temperatures, at up to 9 degrees Fahrenheit milder than average, affected sea ice across the Chukchi Sea, which lies to the northwest of Alaska.
Serreze says research is underway to determine what led to the record warmth throughout the winter, and he suspects part of the answer lies in the strong El Niño event in the tropical Pacific Ocean, which released vast quantities of stored ocean heat into the atmosphere. The other major factors, of course, were human-caused global warming, with a dose of natural climate variability added in for good measure.
Image: Weatherbell analytics
One of the main areas to watch throughout the rest of the melt season is the Beaufort Sea, where a large area of fragmented sea ice exists, extending all the way to the North Pole. This has led to larger, thicker multiyear ice floes surrounded by thinner first-year ice and open water.
The early emergence of open water areas there may mean that, as in 2007, more of the thick, multiyear ice will perish this summer, which continues a long-term trend.
Due to a malfunctioning satellite sensor, some of the NSIDC's exact figures may change, but the overall record will not be affected since sea ice was so far below average.