US government scientists reported yesterday that the Arctic Ocean’s floating ice cover has shrivelled to its second lowest extent since satellite records began in 1979.

Until this month, only once in the last 42 years has Earth’s frozen skull cap covered less than four million sq km.

The trend line is clear: sea ice extent has diminished 14% per decade over that period. The Arctic could see its first ice-free summer as early as 2035, researchers reported in Nature Climate Change last month.

But all that melting ice and snow does not directly boost sea levels any more than melted ice cubes make a glass of water overflow, which gives rise to an awkward question: who cares?

Granted, this would be bad news for polar bears, which are already on a glide path towards extinction, according to a recent study. 

And yes, it would certainly mean a profound shift in the region’s marine ecosystems, from phytoplankton to whales.

But if our bottom-line concern is the impact on humanity, one might legitimately ask, “So what?”

As it turns out, there are several reasons to be worried about the knock-on consequences of dwindling Arctic sea ice.

Perhaps the most basic point to make, scientists said, is that a shrinking ice cap is not just a symptom of global warming, but a driver as well.

“Sea ice removal exposes dark ocean, which creates a powerful feedback mechanism,” Marco Tedesco, a geophysicist at Columbia University’s Earth Institute, told AFP.

Freshly fallen snow reflects 80% of the sun’s radiative force back into space. 

But when that mirror-like surface is replaced by deep blue water, about the same percentage of Earth-heating energy is absorbed instead.

And we’re not talking about a postage stamp area here: the difference between the average ice cap minimum from 1979 to 1990 and the low point reported today – more than 3 million sq km – is twice the size of France, Germany and Spain combined.

The oceans have already soaked up 90% of the excess heat generated by manmade greenhouse gases, but at a terrible cost, including altered chemistry, massive marine heatwaves and dying coral reefs. 

And at some point, scientists warn, that liquid heat sponge may simply become saturated. – AFP, September 22, 2020.