Wednesday, April 1, 2015

Antarctic Hot Spell Gets The Headlines, But The Real Trouble Is In The Ice

Esperanza Base on the northern tip of the
Antarctic Pennisula just recorded what might be
the warmest temperature on record for
Antarctica. But that's not the
real danger in Antarctica if the world warms.
Thawing ice sheets could cause big problems.  
The climate world was abuzz last week with news that Antarctica had its warmest temperature on record.

Readings of 63.5 degrees were reported at Base Esperanza and 63.3 degrees at Marambio, says Christopher Burt at Weather Underground. 

Both weather stations are on the Antarctic Pennisula, which juts north toward the warmer environments of the southern tip of South America.

The standing record for Antarctica was 59 degrees at Vando in 1974, which is definitely closer to the South Pole than the stations that had readings in the 60s last week.

There's no question that the hot temperatures Esperanza and Marambio were highly unusual for Antarctica.

Since records are spotty and don't go back all that far on Antarctica, and not many people are there to monitor the weather there, there's a good possibility it has been hotter than that 63.5 degrees last week.

The bottom line: If you're talking about those warm temperatures in the context of global warming, it's interesting, but doesn't tell you all that much about it.

A little more buried in the headlines, though, was something more ominous, at least in the long term.

Last year we learned that the West Antarctic ice sheet, a huge mass of ice down there, was less stable than originally thought. As warmng ocean water infiltrates underneath it, the ice sheet could eventually collapse, allowing masses of ice on land to flow toward the oceans and melt.

This would raise sea levels substantially around the world, which of course is not a good thing, especially if you live in a coastal city just a few feet above sea level.

Now, we learn the even bigger, gigantic glacier of East Antarctica is also under the same threat of collapse, says the Washington Post. 

Again, warm ocean water is getting beneath the East Antarctica ice sheet, especially the ice shel of the Totten Glacier, thinning it from below.

Says the Washington Post:

"The floating ice shelf of the Totten Glacier covers an area of 90 miles by 22 miles. It is losing an amount of ice 'equivalent to 100 times the volume of Sydney Harbor every year,' notes the Australian Antarctic Division."

That's alarming, because the glacier holds back a much more vast catchment of ice that, were its vulnerable parts to flow into the ocean, could produce a sea level rise of more than 11 feet - which is comparable to the impact from a loss of the West Antarctica ice sheet. And that's a 'conservative lower limit' says lead study author Jamin Greenbaum a PhD candidate at the University of Texas at Austin."

If ice floating on the ocean melts, it's not THAT big a deal in terms of sea level. If ice floating on the ocean melts, it's like an ice cube melting in a glass. The glass doesn't overflow when the ice melts.

But the ice floating on the ocean on the West and East Antartica Ice shelves is holding back masses and masses of ice on land. If the ice shelves melt, the ice from the land moves toward and into the ocean and melts.

That's why the scientists studying this thing are worried about sea levels rising.

Of course, the combined 22 feet of sea level rise from melting the West and East Antartica ice won't happen by, say, Friday. This will go on over decades and centuries, and be a big problem for future generations.  Greenland in the northern hemisphere is melting, too, so that adds to the sea level rise.

The immediate problem is, a little bit of sea level rise can cause big problems.

Gradually, coastal areas will see increased flooding, erosion from storms and salt water intrusion from sea water on fresh water supplies increase. It's already starting to happen. Just ask anyone in Miami, Florida or Virginia Beach/Norfolk, Virginia, for instance, about the increasing number of floods during many high tides.

As is always the case with these types of scientific studies, experts are going to have to do a lot more poking and prodding and questioning and replicating to make sure the conclusions about the East Antarctica ice shelf melting are true.

Nobody has yet physically gotten any equipment into the water beneath the ice shelf to confirm that it's warming as much as they think it is, and the ice is going as fast as they think it is. Instruments and observations do confirm there is a thinning of the ice, but scientists need to refine the measurements more.

Scientists are busily getting on with that work, we're told.

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