Everyone has heard about it: Global warming is causing polar ice to melt.
But is it actually melting? This much-publicized phenomenon, like many others related to global warming, has been attacked by so-called climate skeptics, and getting to the bottom of what is actually going on with the icecaps is not a straightforward matter.
Steve Goreham, executive director of the Climate Science Coalition of America, recently wrote an article in response to a Sept. 20 PBS NewsHour segment about the shrinking Arctic icecap.
The author of the book The Mad, Mad, Mad World of Climatism: Mankind and Climate Change Mania, Goreham accused PBS of ignoring the “elephant in the room.”
He said Arctic ice is indeed melting, but it only makes up about 2 percent of the world’s ice, while 90 percent is found in the Antarctic icecap, which is actually growing, according to data from the National Snow and Ice Data Center.
So does this mean all is well with polar ice?
It is not even pessimistic to say that there will be virtually no sea ice in the Arctic during the summer in 10 years’ time.
—Veijo Pohjola, glaciologist, Uppsala University, Sweden
Not really. According to professor Veijo Pohjola, a glaciologist from Uppsala University in Sweden, “The basic facts in the article are mostly correct, but as always, when you deal with autodidacts [Goreham is not an expert himself in the field], you get errors.”Pohjola explained that sea ice—the ice floating in the oceans—and the ice sheets and glaciers found on land live totally different lives.
Sea ice fluctuates greatly over the seasons, since it is exposed directly to ocean water, while ice sheets and glaciers change very slowly. It is true the Antarctic ice sheet contains most of the world’s ice, but it rests on a continent, while the Arctic ice is all sea ice.
The Antarctic also has a portion of the sea ice, which has actually grown slightly, by about 1 percent, over the past 30 years. In that same period, the Arctic sea ice has shrunk by more than 4 percent. The difference might not seem great, but the results are dramatic, according to Pohjola.
“It is not even pessimistic to say that there will be virtually no sea ice in the Arctic during the summer in 10 years’ time,” said Pohjola.
There is controversy among scientists over whether or not the growth in the Antarctic sea ice is statistically significant. Goreham says it is, and Pohjola agrees on this point, but says more research is needed to understand why this is happening.In any case, Pohjola said, current climate models predict that the effects of global warming will show faster and more clearly in the Arctic.
The reason is that ocean currents such as the Gulf Stream are like a highway of warm water stretching from the equator to the Arctic, while the ocean currents around the Antarctic are different, where not as much heat exchange is occurring.
Greenland Ice Drop Off
So, forgetting for now the fate of the polar bears, if most of the world’s ice is bound up in the ice sheets, and the Antarctic ice sheet is actually growing, does this mean there is no risk of a “Waterworld” scenario? In this 1995 movie, global warming has caused the polar icecaps to melt, covering the entire Earth in water.
Again, reality is more complex, Pohjola said.
“Eight-five percent of the world’s glacier ice is found in the Antarctic, but the remaining 15 percent is still enough to raise the sea level by 7 or 8 meters [22–26 feet], so I think the public should be aware,” he said.
Most of this 15 percent is found on Greenland in the Arctic, where dramatic developments have taken place in the last few years, with big chunks of ice dropping off and floating off to sea.
This is, according to Pohjola, probably due to the ice sheet being undermined from below by the increased ocean temperature.
Furthermore, this phenomenon has also been observed in west Antarctica.
The eastern Antarctic ice sheet has grown some, due to increased precipitation, again an effect of global warming, according to Pohjola. However, the western part has lost six times as much mass, based on gravimetric studies. This is very hard to measure, however, Pohjola added.
Goreham, meanwhile, said there are “differing conclusions” regarding Greenland, and he is skeptical of the gravimetric studies.
“Gravimetric measurements from the NASA GRACE satellites have been shown to be subject to large errors and have established nothing ‘beyond doubt,’” he said.
“In addition, scientists have only a few years of gravimetric data. Such data are subject to short-term fluctuations in ice and do not have an estimate of what has been occurring over decades of time for either Greenland or Antarctica.”
Ice Loss or Gain?
Goreham said he believes Greenland is only “melting near the edges as the Earth warms naturally from the cold period of the Little Ice Age, but is getting thicker in the center from accumulating snow.”
He cited an example of a group of airplanes left on Greenland in 1942 that was found hidden under 270 feet of ice.
Again, while this may seem striking, “This reflects a lack of understanding of the dynamic flow of the ice,” Pohjola said.
“Even if an ice sheet loses mass, the upper parts will always accumulate mass, while the ice is moving downward and out to sea. This means that Greenland could still be losing incredible amounts of mass, but these airplanes will sink and snow over,” he noted.
This kind of back-and-forth between the skeptics, dubbed “deniers” by some, and those who can be said to represent the scientific mainstream, dubbed “climatists” by some, most likely becomes impossible to navigate for a layman at a certain point.
Pohjola believes that, as a scientist, he must continue to do his best to present complicated scientific facts in an understandable way, especially on important and controversial matters like global warming.
“It is the only way [to] gain the public’s trust,” Pohjola said.
He added, “Extremists on both sides of the climate debate seldom listen to scientific arguments. They take our careful claims and uncertainty as a sign that we don’t really know. But they don’t understand our way of reasoning.
“You could actually sum up all the signs we are seeing right now with the expression, ‘If it walks like a duck and quacks like a duck, it probably is a duck.’”
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