Greenland Is Melting At Alarming Rate
Jay Zwally heads NASA’s ICESat (Ice, Cloud and Land Elevation Satellite) project to measure changes in the amount of ice in the earth’s polar regions. One of the world’s top glaciologists, he is based at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. His comments are adapted from a talk with NPQ in late June.
Swiss Camp, Greenland—For most of the last 30 years, Greenland has been what we glaciologists call “in zero balance”—meaning that as much ice was formed each year as was lost. In other words, Greenland was stable. What we’ve seen lately is a marked increase of surface melting and acceleration of outlet glaciers—the net loss of up to 50 cubic kilometers of ice volume annually.
The total amount of ice going out in icebergs and melt water is 10 percent greater than all the ice coming in from snowfall, which means that Greenland is now in a state of definitive loss of ice volume.
We’ve also discovered something new—the so-called “lubrication” effect in which warmer melt water formed at the surface works its way down beneath the glaciers and causes a speedup in the ice flow toward the melting edges, increasing the amount of melt water and icebergs going into the sea.
The cause of Greenland melting is without doubt due to atmospheric warming as well as ocean warming, which affects the outlet glaciers. The strong evidence is that this is due to climate warming from C02 forming a carbon blanket in the atmosphere.
So far, only 0.6 of a degree centigrade temperature increase has been attributed to the “greenhouse effect.” Even noted skeptics agree that temperatures will increase 1.8 degrees over the next century because of climate change. And the best climate models predict an even larger warming. The big effects we are already seeing are only a third or more of what we have to look forward to in terms of the impact of warming. This means that perhaps half of Greenland may cease to exist over the next few centuries.
Sea levels at present are rising one foot per century due to ocean warming and melting of small glaciers. When we add the Greenland melt to the mix, we may now be looking at three to four feet per century. Aside from raising sea levels, all that fresh water diluting the salinity of the sea could have major effects on ocean circulation and temperatures in the North Atlantic.
Rising temperature is driving the melting of Greenland. Temperature rises are driven by greenhouse gases, mainly carbon dioxide. The models have predicted that these gases would cause climate warming beyond the natural variability, and then start to go up dramatically. That is exactly what is happening.
Temperatures are increasing far beyond anything we’ve seen in millennia. And the effects of the warming on the ice are faster than many of us thought.
The biggest uncertainty we face today is not in the climate models but in what we are going to do about climate change. We are going on with business as usual. We’re not doing anything about it. We are going full speed ahead as if we don’t have to heed the warning signs. If we continue, we will see consequences not three times what we see now—the lowest predictions—but six times. We’re really facing big, big shifts from beetles invading forests in the American Northwest to hurricanes like Katrina.
Just to look at America alone, as Katrina demonstrated in New Orleans, climate change is rapidly becoming a national economic and security issue. It will have a vast impact on the lives of people, especially along the coasts, and may well end up bankrupting insurance companies as storm damage piles up upon storm damage year after year. If that doesn’t make us change our voracious pattern of carbon fuel use, I don’t know what will.