Greenland's Melt Zone Now Reaching One Mile In Altitude - NYT

[hatrack]

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"In the last few years, Greenland's melt zone, where summer warmth turns snow on the edge of the ice cap into slush and ponds of water, has expanded inland, reaching elevations more than a mile high in some places, said Dr. Konrad Steffen, a glaciologist at the University of Colorado.

Recent measurements by NASA scientists show that such melting can have outsize effects on the ice sheet. Meltwater formed on the surface each summer percolates thousands of feet down through fissures, allowing the ice to slide more easily over the bedrock below and accelerating its slow march to the sea.

Some jutting tongues of floating ice, where riverlike glaciers protrude into the sea, are rapidly thinning. Measurements this year by Dr. Steffen and others on the Petermann Glacier in northern Greenland show that more than 150 feet of thickness melted away under that tongue in the last year. Such melting can speed the seaward movement of ice in the same way that removing a doorstop lets a door swing freely.

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Some oceanographers say global warming may already be pushing the North Atlantic toward instability. In less than 50 years, waters deep in the North Atlantic and Arctic have become significantly fresher, matched by growing saltiness in the tropical Atlantic. Worldwide, seas have absorbed enormous amounts of heat from the warming atmosphere. A big outflow of water from Greenland could take the system to a tipping point, some say. In past millenniums when such oceanic breakdowns occurred, the climate across much of the Northern Hemisphere jumped to a starkly different state, with deep chills and abrupt shifts in patterns of precipitation and drought from Europe to Venezuela. Some changes persisted for centuries. But whether something similar is likely to result from the new melting in Greenland is far from clear. The forces that caused abrupt climate change in the past, like monumental floods released from collapsing ice-age glaciers, are different from the much slower ones being measured today."

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[donsu]

1. it's too late, all we can do now is prepare for the worst

nt

[IrateCitizen]

2. I was intrigued by the inadequacy of the climate models available

But whether something similar is likely to result from the new melting in Greenland is far from clear. The forces that caused abrupt climate change in the past, like monumental floods released from collapsing ice-age glaciers, are different from the much slower ones being measured today.

Gaps in understanding are enormous. Scientists have been unable to devise computer simulations that consistently replicate past jolts to the climate, leaving intellectual heartburn about the future.

"The models are not nearly as sensitive as the real world," Dr. Richard B. Alley, an expert at Penn State on Greenland's climate history, said. "That's the kind of thing that makes you nervous."

What I see inherent in a statement such as this one from Dr. Alley is the fact that we truly understand so little about how our natural systems truly operate. While a conservative thinker would see this and say, "Well, then that means we shouldn't change our ways because we have no idea if what we do will make things worse," for me it highlights the need to vastly decrease our collective ecological footprint on the earth.