2 January, 2017

What does Greenland's Petermann glacier tell us?

Warming evangelist Chris Mooney below focuses on a glaciologist, Andreas Muenchow, who studies the Petermann glacier and notes that Muenchow has become more convinced that, over time, the glacier has been shrinking.  It probably is.  Glaciers advance and retreat all the time.  As some melt, others will be advancing -- usually in response to movements in precipitation.   So you can make no valid generalizations from what one glacier does.

And the amusing part is that the Petermann is a SHELF -- floating ice -- and we have known since Archimedes that the melting of floating ice does not raise the water level.  Mooney indirectly acknowledges that by saying that the Petermann is "holding back" other ice.  Maybe.  But if the other ice is grounded why should anything move it other than its own internal processes?

Mooney is just a teller of tall tales

So let us look at what Mooney does NOT tell us.  I have long said that volcanic heat at both poles stands behind a lot of occasional ice melts.  So let us see what Muenchow says about that.  Below is a recent (2016) abstract from an article by him:

Melting of the Greenland Ice Sheet represents a major uncertainty in projecting future rates of global sea level rise. Much of this uncertainty is related to a lack of knowledge about subsurface ocean hydrographic properties, particularly heat content, how these properties are modified across the continental shelf, and about the extent to which the ocean interacts with glaciers. Early results from NASA’s five-year Oceans Melting Greenland (OMG) mission, based on extensive hydrographic and bathymetric surveys, suggest that many glaciers terminate in deep water and are hence vulnerable to increased melting due to ocean-ice interaction. OMG will track ocean conditions and ice loss at glaciers around Greenland through the year 2020, providing critical information about ocean-driven Greenland ice mass loss in a warming climate.

Muenchow explicitly admits that subsurface heat might cause the melting, not anthropogenic global warming.  Need I say more?


As one of Greenland’s largest ice shelves shrinks, a once-doubtful scientist has come around to the role of climate change in melting it.

Half a decade before he took this trip to the farthest reaches of the north, Andreas Muenchow had his doubts about whether warming temperatures were causing one of the world’s great platforms of ice to melt and fall apart.

He even stood before Congress in 2010 and balked on whether climate change might have caused a mammoth chunk of ice, four times the size of Manhattan, to break off from this floating, 300-square-mile shelf. The University of Delaware oceanographer said he wasn’t sure. He needed more evidence.

But then the Petermann Ice Shelf lost another two Manhattans of ice in 2012, and Muenchow decided to see for himself, launching a project to study the ice shelf intensively.

He was back again in late August, no longer a skeptic. It was hard not to be a believer here at 81 degrees north latitude, where Greenland and Canada very nearly touch. The surface of the bumpy and misshapen ice was covered with pools and puddles, in some cases frozen over but with piercing blue water beneath. Streams carved through the vast shelf, swelling into larger ponds or even small lakes.

The meltwater was a sign the ice shelf was growing more fragile, moving closer to the day when it might give up more city-size chunks of ice.

The Petermann Ice Shelf serves as a plug of sorts to one of Greenland’s largest glaciers, lodged in a fjord that, from the height of its mountain walls down to the lowest point of the seafloor, is deeper than the Grand Canyon. There’s enough ice piled up behind Petermann to raise oceans globally by nearly a foot someday.

The question for Muenchow is no longer whether Petermann is changing — it’s how fast it could give up still more ice to the seas.

SOURCE






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