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Don Paul: Greenland ice is melting faster than expected

Don Paul

That Greenland’s ice mass is melting faster than projected is no small thing. Simply put, it is a big thing and a bad thing for the planet.

A study published this week in the Proceedings of the National Academy of Sciences and summarized by National Geographic demonstrates the loss of ice mass is proceeding much faster than had been expected. A warming climate is the culprit, as you might guess. It is the Arctic region where warming is proceeding fastest, as forecast decades ago in early climate models.

Greenland is the world’s largest island. Its ice mass is second only to much larger Antarctica, a continent.

Michael Belvis, an Ohio State University geoscientist, is the lead author in this newest study. He is convinced Greenland has hit a “tipping point” in ice loss. That point began around 2002-2003, when ice mass loss radically accelerated. Belvis told National Geographic ice loss had increased by 2012 to four times the rate of loss in 2003, which was “unprecedented.” Much of this accelerated loss came from a part of Greenland which previously had been experiencing less ice loss than most of the rest of the island, the southwest portion. The ice loss from other parts of Greenland had been mainly from ice discharges, breaking off into the sea. This southwest ice loss has been mainly meltwater, as “rivers which flow into the sea.”

Hard data gathered by NASA’s Grace Satellite and coastal GPS stations show the average annual ice loss between 2002 and 2016 was 280 billion tons. That annual loss is enough to cover Florida and New York State hip-deep in meltwater, along with Washington, D.C., and one or two other small states.

To give you some sort of scale, were a total meltdown on Greenland to occur, sea levels would rise by 7 meters, or 23 feet. (Those numbers are dwarfed by the Antarctic ice mass. If melted, sea levels would go up 57 meters, or 187 feet.)

Up until now, I had assumed a near or total Greenland meltdown was beyond the range of our warming climate. I assumed wrong. Of course, I’m no glaciologist. Penn State glaciologist Richard Alley states an unabated period of warming would indeed, over a few centuries, produce that meltdown. Yes, not a one of us or even our children would be here to witness that endpoint. But on the way to that meltdown, with continued warming, the impacts on humanity and the planet would bring on many catastrophes, some gradual, and some relatively rapid.

So far, the global mean temperature has risen 1 degree C since 1880 (due mainly or entirely to human activity), and we already have this rapid acceleration in melting. Alley and other glaciologists calculate if we don’t cap off the warming, in just a few decades the Greenland ice loss will become irreversible. With the loss of ice, especially on the southwest part of Greenland, temperatures will rise above freezing more often. That has already become more common in recent years. It used to be very rare for surface readings to go above freezing. Of course, that hastens melting.

Again, a loss of most or all of Greenland ice would raise sea levels 23 feet. What happens then? An earlier study found: “If global carbon emissions continue to increase at the current rate, it could lead to an increase in sea levels of up to 23 feet by the end of this century, submerging more than 1,400 cities and towns in the U.S., including Miami, Virginia Beach, Sacramento and Jacksonville.” By the way, U.S. carbon dioxide emissions had been going down for at least a decade, due largely to utilities abandoning coal and switching to natural gas, along with reduced industrial activity during the recession. Now, our emissions are rising again. We’re not going to catch up with China, but we went up by 3.4 percent last year, while global emissions went up 2.7 percent.

Another effect from the warming in the Arctic has been the impact of the North Atlantic Oscillation (NAO). When the NAO is in its negative phase in the winter, it can bring cold and stormy weather to the East Coast. But now in the summer, with ongoing warming, the other edge of the NAO pumps warm air up into Greenland in its negative phase. Until earlier this century, a negative NAO did not bring summer warming to Greenland. So, that too has added to the accelerated warming on the island.

There has long been theoretical evidence that increased fresh meltwater flowing into the North Atlantic would dilute its salinity. Lower salinity, it’s been thought, would weaken the Gulf Stream. The Gulf Stream is what brings temperate weather to western Europe.

Now, hard data shows in a study last year in Nature that the Gulf Stream has weakened by about 15 percent since the mid-20th  century. Many meteorologists believe this weakened oceanic flow is responsible for more frequent extreme heat waves in Western Europe in recent years. From the National Geographic article: “A co-author of the Nature study, Stefan Rahmstorf of the Potsdam Institute for Climate Impact Research in Germany, attributed the slow-down to the huge volumes of meltwater from Greenland. “I think it is happening….And I think it’s bad news,” he told the Washington Post.

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