By Brian Resnick@B_resnickbrian@vox.com
The Arctic Ocean once froze reliably every year. Those days are over.
Arctic sea ice extent has been measured by satellites since the 1970s. And scientists can sample ice cores, permafrost records, and tree rings to make some assumptions about the sea ice extent going back 1,500 years. And when you put that all on a chart, well, it looks a little scary.
In December, NOAA released its latest annual Arctic Report Card, which analyzes the state of the frozen ocean at the top of our world. Overall, it’s not good.
“The Arctic is going through the most unprecedented transition in human history,” Jeremy Mathis, director of NOAA’s Arctic research program, said at a press conference. “This year’s observations confirm that the Arctic shows no signs of returning to the reliably frozen state it was in just a decade ago.”
The report, which you can read in full here, compiles trends that scientists have been seeing for years. The Arctic is warming at twice the rate of the rest of the world. And 2017 saw a new record low for the maximum sea ice extent (i.e., how much of the Arctic ocean freezes in the coldest depths of winter).
NOAA
That huge drop-off at the end? That’s “the largest magnitude decline in sea ice, and the greatest sustained rate in sea ice decline in that 1,500-year record,” said Emily Osborne, the NOAA scientist who compiled the data for the chart.
There is some natural variability, and a fairly wide range of error in these assumptions, she said. But even accounting for that, it’s clear we’re living through something unprecedented. And it seems to be getting worse very quickly: “This was the third straight year of a record low winter maximum,” the report concludes.
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