By David L. Brown
As we all know by now there is no global warming or climate change, thanks to a concerted effort by deniers to insist that we all put our fingers in our ears and recite “La, la, la I can’t hear you”. Unfortunately, they forgot to tell Mother Nature because the planet continues to show signs of warming and as far as climate change, well just turn on the Weather Channel and draw your own conclusions.
One of the most significant “canaries in the mine” that I’ve been following for some time is the extent of Arctic sea ice. The Arctic ice cap has been melting fairly steadily, and I predicted about seven or eight years ago that we would see an essentially ice free Arctic Ocean by 2015. At that time the experts were saying it wouldn’t take place until the end of the 21st century, and while I was probably setting too early a target, the trends certainly indicate that it will almost certainly happen far sooner than was thought just a few years ago.
Why is the Arctic ice important? For one thing, it provides a heat shield for the Arctic Ocean itself, preventing it from absorbing solar rays during the long period of 24-hour Midnight Sun during the months of summer. Ice and snow reflect heat back into space, while open water is dark and absorbs the rays. The more open water is exposed, the more heat is absorbed.
This matters not only because it represents de facto global warming, but also because the Arctic is an important “climate regulator” and if it’s disrupted it can create havoc, particularly in the North Atlantic. That can cause climate effects in major population centers of North America and Europe, including the possible disturbance of the Gulf Stream, the warm waters of which prevent northern Europe from being like Siberia which is at a similar latitude but has quite different climate conditions.
Right now the Arctic ice cover is at its lowest point ever for this date, as shown in the graph at left. The blue line represents this year’s ice coverage as of yesterday, August 13, 2012. The dotted line is the record low point set in 2007. Above that is the average for the previous 20-year 1979-2000 period (represented by the solid black line) and the effect of two standard deviations to that average shown by the gray band. As you can see, not only has the 2012 ice coverage extent exceeded the record low, right now it’s taking a decidedly downward turn. All in all, we’re way out of what was normal during the last two decades of the 20th century. (I’ve cropped all but the most recent data points from the graph. You can see the whole thing here.)
One of the factors that’s often overlooked in evaluating the extent of sea ice is that it is a two-dimensional view of the situation. In other words, it only shows the ice covered areas versus open water. But like most things the ice is three dimensional. In other words, in addition to its surface area the ice has the third dimension of thickness, and that dimension has been steadily decreasing. Thus, the total mass of ice is far less than it was in past years, and thus the rate of melting is able to increase because there’s less total ice to melt. To understand this, you merely need to put a block of ice out on the driveway in front of your house in July (assuming you live in the Northern Hemisphere) and watch. At first the ice will seem to melt very slowly, almost like watching grass grow. But as thawing proceeds the rate appears to speed up until toward the end it virtually disappears before your eyes.
Something like that could be taking place in the Arctic Ocean. I haven’t looked up recent figures, but a few years ago to the best of my recollection I reported that the ice had averaged about ten feet in thickness back in the 1950s, and by the early 2000′s it had been reduced to only about three feet. It’s probably even thinner today, making the ice cover even more prone to disappearing. At right is a map of the present coverage, again as of August 13. Both these graphics are from the website of the National Snow and Ice Data Center (see link above). The white area, of course, shows the extent of the ice coverage and the purple lines indicate the previous “normal” boundaries, again the average during the 1979-2000 decades.. There’s obviously a lot of open water right now that was ice-covered at this date in past year, and that water is happily absorbing those solar rays. The annual minimum coverage, by the way, usually occurs in mid-September so we have about another month of melting ahead.
You might note the little X in the right center of the ice area. That represents the North Pole. A friend of mine recently visited that remote spot on a nuclear-powered Russian ice breaking ship. I remember a few years ago reading about how a similar vessel arrived at the pole to discover an area of open water…the pole itself was ice free. Quite a disappointment for the tourists I’m sure, because one of the great thrills of taking such an expensive trip is to get out and walk around on the ice at the top of the world.