The Rains of Antarctica are Coming — Warm Summer Storms Melted Texas-Sized Section of Ross Ice Shelf Surface During 2016

“In West Antarctica, we have a tug-of-war going on between the influence of El Niños and the westerly winds, and it looks like the El Niños are winning. It’s a pattern that is emerging. And because we expect stronger, more frequent El Niños in the future with a warming climate, we can expect more major surface melt events in West Antarctica (emphasis added).” — David Bromwhich, co-author of a recent study identifying massive summer surface melt in West Antarctica during 2016.

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If you’re concerned about human-caused global warming, then you should also be concerned about ice. In particular — how warming might melt a miles-high pile of the frozen stuff covering the massive continent of Antarctica.

During recent years, scientists have become more and more worried as they’ve observed warming oceans eating away at the undersides of floating ice sheets. This particular process threatens numerous cities and coastal regions with swiftening sea level rise as ice margins melt and glaciers the size of mountain ranges clamor for release into the world’s oceans.

Major Antarctic Surface Melt Event During 2016

But another potential process in a still warmer world threatens to compound the impact of the heating waters that are already melting so many of the world’s glaciers from the bottom up — large scale surface melt.

(A major warming event during January of 2016 turned a Texas-sized section of Antarctica’s surface into slush. This occurred as a storm running in from the Southern Ocean delivered warm air and rainfall to sections of West Antarctica. Scientists are concerned that more major surface melt is on the way for Antarctica as the Earth’s climate heats up and that repeated warming and rainfall events in this typically-frozen region may further quicken rates of sea level rise. Image source: Earth Nullschool.)

During January of 2016, as a very strong El Nino was combining with human-caused global warming to spike atmospheric temperatures to 1.2 C above 1880s levels, something pretty strange and concerning happened. Over the course of about 15 days, a 300,000 square mile section of the Ross Ice Shelf surface and nearby lands over West Antarctica experienced melting. This mass slushing across Antarctica’s surface occurred as a warm storm swept in from the Southern Ocean (see image above) to deliver an unheard of rainfall event to the region.

West Antarctica is typically too cold for such weather. It is also often too dry. The region is well know by climate researchers as a frozen desert. But as human-forced climate change has warmed the nearby ocean, warm, moist winds blowing in from these heating waters have become more frequent.

Westerlies Interrupted by Warming Ocean

Antarctica is typically protected by strong westerly winds that keep both heat and moisture out. But a warming ocean environment, according to Ohio State researchers, is enabling El Nino to interrupt these westerlies and hurl increasing volumes of heat and moisture over the glaciers of Antarctica. In 2016, countervailing winds pushing against the typically prevailing westerlies bore with them an odd rainstorm that set off a massive surface melt event.

(Surface melt over a large section of West Antarctica lasted for as much as 15 days as heat and moisture from the surrounding ocean beat back a protective barrier of westerly winds and invaded the frozen continent. According to scientists, these events are likely to become more frequent and long-lasting as the climate warms. Image source: Ohio State University.)

When combined with already-active melt from ocean warming, surface melt could further serve to destabilize ice sheets and swiften sea level rise. This was exactly the concern that David Bromwich, an Antarctic researcher at Ohio State and co-author of the paper that identified this strange event highlighted in this statement (please see related Washington Post article here):

“It provides us with a possible glimpse of the future. You probably have read these analyses of West Antarctica, many people think it’s slowly disintegrating right now, and it’s mostly thought to be from the warm water eating away at the bottom of critical ice shelves. Well, that’s today. In the future, we could see action at the surface of these ice shelves as well from surface melting. So that makes them potentially much more unstable (emphasis added).”

It’s worth noting that this particular storm, though unusual and noteworthy, did not produce too much in the way of surface melt ponding. Instead, the storm turned a large section of the Antarctic surface to a slurpee-like slush. But this event did deliver a considerable amount of heat to the Ross Ice Shelf region. And repeated instances could serve to seriously soften this massive ice formation.

Eventually, as warming worsens, significant surface melt and flooding could help to shatter large buttressing ice shelves like Ross or even generate risks of surface glacial outburst flooding in instances where permanent surface melt lakes form behind an ice dam. But the primary concern at this time is that these warm rain events provide a compounding melt influence that adds to risks for more rapid sea level rise this Century.

Links:

Widespread Snowmelt in Antarctica During Unusually Warm Summer

Scientists Stunned by Antarctic Rainfall and Melt Area Bigger Than Texas

Scientists Report Large Scale Surface Melting Event in Antarctica During 2015-2016 El Nino

The Ross Ice Shelf

Earth Nullschool

Hat tip to TodaysGuestIs

Did Föhn Winds Just Melt Two Miles of East Antarctic Surface Ice in One Day? 

UPDATE — Cloud Shadows and Bluish Coloration

Layer analysis of the November 27 MODIS satellite image in bands M  1-12 reveals two cloud shadows near the suspect melt pond (an issue that commentators Hendrick and Sammy raise in discussion below). The separate true color image provides comparison and generates the impression that the suspect melt pond is simply a remnant cloud shadow from the kidney-shaped cloud in the M 1-12 band image.

cloud-shadow-vs-suspect-melt-pondnon-corrected-radiance

The cloud shadows move from frame-to-frame providing a further negative confirmation.

Though it is now certain that the large blue blotch in this satellite image is not a melt pond, a bluish coloration appearing over a broad swath of the above region in both the November 27 and November 28 image frames appears to indicate the presence of surface melt. So the downsloping wind related warming may well have produced a more subtle surface melt for this region of East Antarctica.

UPDATE 2 — Small Melt Ponds Visible in Hi Res Satellite Imagery

High resolution satellite imagery confirms surface melt in the region of recent föhn wind activity on November 27 through 28. Note the ponding and bluing in this close-up shot from the S2A instrument.

small-melt-ponds-bluing

(Surface melt visible along the Scott Coast in East Antarctica. Edge of frame for the above image is approximately two miles. Hat tip to Darvince, Tealight and the Arctic Sea Ice Forum. )

So it appears that this abnormal weather/climate event did result in springtime melt in East Antarctica — if not at the scale initially feared. Still rather concerning.

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It’s right there in the satellite image. A swatch of blue that seems to indicate an approximate 2-mile long melt lake formed over the surface of East Antarctica in just one day. If confirmed, this event would be both odd and concerning. A part of the rising signal that melt stresses for the largest mass of land ice on the planet are rapidly increasing.

melt-pond-scott-coast-antarctica-november-27-2016

(Possible large melt lake on the surface of an ice shelf along the Scott Coast appears in this NASA satellite image. The melt lake seems to have formed after just one day during which föhn winds ran downslope from the Transantarctic Mountain Range — providing a potential period of rapid heating of the glacier surface.)

Surface Melt Now Showing Up in East Antarctica

While scientists and environmentalists are understandably concerned about ocean warming melting the undersides of sea-fronting West Antarctic glaciers — resulting in risks for rapid sea level rise for the near future, another consequence of global warming is also starting have a more visible impact on the frozen and now thawing continent. Surface melt, which was hitherto unheard of for most of East Antarctica, is now starting to pop up with increasing frequency.

East Antarctica, according to Stewart Jamieson, a glaciologist at Durham University in the U.K., is “the part of the continent where people have for quite a long time assumed that it’s relatively stable, there’s not a huge amount of change, it’s very, very cold, and so, it’s only very recently that the first supraglacial lakes, on top of the ice, were identified.”

But now, even in austral springtime, we find evidence of surface melt in the satellite record.

On November 27, 2016, what looks like an approximate 2 mile long melt pond appeared in a section of ice shelf along the Scott Coast and just North of the Drygalski Ice Tongue in the region of McMurdo Sound. The suspect lake — which is visible as a light blue swatch at center mass in the NASA-MODIS satellite image above — suddenly showed up in the November 27 satellite image along a region where only white ice was visible before. And it appears in a region of East Antarctica that, before human-forced warming altered the typically-stable Antarctic climate, had rarely, if ever, seen surface melt.

near-freezing-temps-scott-coast-fohn-winds

(Near melting point temperatures appear along the Scott Coast in conjunction with an apparent föhn wind event. Image source: Earth Nullschool.)

The pond shows up coordinate with recorded near 0 C surface temperatures in the GFS monitor for November 26-27 and along with evidence of downsloping (föhn) winds. GFS indicators show downsloping winds gusting to in excess of 50 mph over the period. Such winds have the potential in increase surface temperatures by as much as 14 degrees Celsius in a matter of minutes. And they have, increasingly, produced surface glacial melt events in regions of Greenland and Antarctica during recent years.

Surface Melt as a Feature of Glacial Destabilization

Supraglacial lake is just another word for a surface glacial melt lake. And these new lakes pose a big issue for ice sheet stability. Surface melt lakes are darker than white glacier surfaces. They act as lenses that focus sunlight. And the comparatively warm waters of these lakes can flood into the glacier itself — increasing the overall heat energy of the ice mass.

nasa-greenland-surface-melt

(A NASA researcher investigates a surface melt pond in Greenland. During recent years, these climate change related features have become more common in Antarctica. Image source: NASA.)

But water at the glacier surface doesn’t just sit there. It often bores down into the ice sheet — producing impacts for months and years after the surface lake’s formation. Sub surface lakes can form in the shadow of surface ponds. Transferring heat into the glacier year after year. In other cases, water from these lakes punches all the way to the glacier’s base. There the added lubrication of water speeds the glacier’s flow. All of these processes generate stresses and make glaciers less stable. And it is the presence of surface melt ponds that has been responsible for so much of Greenland’s speeding melt during recent years.

Now, a similar process is impacting the largest concentration of land ice on the planet. And while Greenland holds enough ice to raise sea levels by around 21 feet, East Antarctica contains enough to lift the world’s oceans by about 195 feet. Surface melt there, as a result, produces considerably more risk to the coastal cities of the world.

 

Links:

NASA-MODIS (#ThanksNASA)

These Stunning Blue Lakes Give us New Reason to Worry About Antarctica

Earth Nullschool

New Maps Chart Greenland Glaciers’ Melting Risk

Hat tip to Shawn Redmond (and a special thanks for being the first here to ID the rather odd apparent melt pond forming along the Scott Coast.)

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