Treehugger Tuesday

From Mother Nature News:

7 Reasons Why Arctic Sea Ice Matters
Russell McLendon
November 19, 2018, 11:30 a.m.

The vanishing veneer of frozen ocean isn't just vital for polar bears.

Ice in the central Arctic Ocean has thinned by more than 60 percent since 1975.

The Arctic hasn't been itself lately. Temperatures there are rising at twice the global rate, sparking an array of changes unlike anything seen in recorded history.

One of the most striking examples is the region's sea ice, which is now declining by about 13 percent per decade, with the 10 lowest seasonal minimums all recorded since 2007. In September 2018, Arctic sea ice tied for its sixth-lowest extent on record, according to the National Snow and Ice Data Center (NSIDC).

"This year's minimum is relatively high compared to the record low extent we saw in 2012, but it is still low compared to what it used to be in the 1970s, 1980s and even the 1990s," says Claire Parkinson, a climate change senior scientist at NASA's Goddard Space Flight Center, in a statement.

Arctic sea ice always waxes and wanes with the seasons, but its average late-summer minimum is now shrinking by 13.2 percent per decade, according to the U.S. National Oceanic and Atmospheric Administration (NOAA). And according to a 2017 study published in the journal Geophysical Research Letters, satellite estimates of Arctic sea ice may have been overestimated by as much as 25 percent, suggesting the meltdown is even more severe than previously thought.

Scientists widely agree the main catalyst is human-induced climate change, boosted by a feedback loop known as Arctic amplification. (Antarctic sea ice, meanwhile, is more buffered against warming.) The basic problem has become well-known even among laypeople, thanks largely to its compelling effect on polar bears.

But while many people realize humans are indirectly undermining sea ice via global warming, there's often less clarity about the reverse of that equation. We know sea ice is important to polar bears, but why is either one important to us?

Such a question overlooks many other dangers of climate change, from stronger storms and longer droughts to desertification and ocean acidification. But even in a vacuum, the decline of Arctic sea ice is disastrous — and not just for polar bears. To shed some light on why, here are seven of its lesser-known benefits:

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