Polar Ice Is Lost at Sea

Our planet reached another miserable milestone earlier this week:  Sea ice fell to its lowest level since human civilization began more than 12,000 years ago.

That worrying development is just the latest sign that rising temperatures are inflicting lasting changes on the coldest corners of the globe.  The new record low comes as the planet’s climate system shifts further from the relatively stable period that helped give rise to cities, commerce, and the way we live now.

So far, the new year has been remarkably warm on both poles.  The past 30 days have averaged more than 21 degrees Fahrenheit warmer than normal in Svalbard, Norway — the northernmost permanently inhabited place in the world.  Last month, a tanker ship completed the first wintertime crossing of the Arctic Ocean without the assistance of an icebreaker.  Down south in the Antarctic, sea ice is all but gone for the third straight year as summer winds to a close.  

The loss of Earth’s polar sea ice has long been considered one of the most important tipping points as the planet warms.  That’s because as the bright white ice melts, it exposes less-reflective ocean water, which more easily absorbs heat.  And that, sorry to say, kicks off a new cycle of further warming.

According to  research published last fall, that cycle appears to be the primary driver of ice melt in the Arctic, effectively marking the beginning of the end of permanent ice cover there. The wide-ranging consequences of this transition, such as more extreme weather and ecosystem shifts, are already being felt far beyond the Arctic.

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