Posted by
Doc Stephens on Saturday, June 21, 2008 1:16:05 PM
The News Scan section of the July 2008 edition of Scientific American includes an article by Editor, Peter Brown, entitled "Climate Change: Polar Express - Ice is melting at the poles much faster than climate models predict." The article includes a photograph with the following caption "Shattered fragments of ice are all that remain of a 160-square-mile area of Antarctica's Wilkins ice shelf—dramatic evidence of climate warming around the Antarctic Peninsula." The first sentence of the article states: "The accelerating pace of climate warming in the earth's polar regions is spurring a new sense of scientific urgency." What's wrong with this? Several things! And it is quite illustrative.
Scientific American is a well respected periodical that has been around for a very long time--more than 150 years. I've personally had a subscription for more than 50 years. Obviously, I enjoy reading this publication. Nevertheless, it provides a nice example of journalistic bias--agenda journalism. I expect better from a scientific publication of this stature. I expect balanced reporting, especially in the news section. I don't expect exaggeration and distortion.
Ice always melts in the summer and no climate models are able to predict the amount of ice melt for a given summer. During the most recent summer in the southern hemisphere the sea ice decreased to 2.1 million sq-km which was the third greatest amount of summer sea ice in the past 30 years. And the three years out of the last 30 showing the greatest extent of summer sea ice in the southern hemisphere were all in this current decade: 2001, 2003, and 2008. There is as much as 16,000,000 square-kilometers of sea ice in the southern hemisphere during the winter months. The most ever recorded using satellite imagery over the past 30 years was during the most recent winter. This is according to data from NSIDC and NASA. There is no discernable trend in the amount of sea ice in the southern hemisphere. The amount of sea ice in the summer and winter varies each year by as much as a million square kilometers.
Temperature records over the past 50 years in Antarctica have been studied and reported by a number of scientists. Mohaghan, et al reported in the Journal of Geophysical Research in 2007 that near surface temperatures from 15 recording stations in Antarctica excluding the Antarctic Peninsula showed no statistically significant temperature fluctuations over the continent--which is larger than the United States--with one exception, the reporting station at the South Pole has cooled at a rate of -0.17 K per decade. The South Pole has gotten cooler over the past 50 years—contrary to implications in the News Scan piece.
There has been warming on the Western Antarctic Peninsula, particularly in the area referenced in the Peter Brown News Scan article--all 160 square miles (414 sq-km). This area represents less than a thousandth of one percent of the area of sea ice in the southern hemisphere. It is warmed by a southern oceanic current which oscillates on a multi-decadal cycle—currently in a warm period. It will get cold again over the next few decades. The Western Antarctic Peninsula also has experienced increased snowfall over the past 50 years, apparently due to increased moisture from the relatively warm current near the peninsula. Thomas, et al, reported this in Geophysical Letters, 2007. Even the IPCC, in 2007 reports "Antarctic sea ice extent continues to show inter-annual variability and localized changes but no statistically significant average trends, consistent with the lack of warming reflected in atmospheric temperatures averaged across the region."
What about the "accelerating pace of climate change in the earth's polar regions" and how does this compare with recent studies. This past April, a group of researchers at the TRACE 2008 Conference in Zakopane, Poland, reported on a study of climate variation, cycles and trends, as determined from preserved Scots Pine tree rings in Finland (Mielikainen, et al). The study covered 7,641 years and focused on summer temperatures on both sides of the present timberline in Finland. The most obvious conclusion from this study is that temperature and other variables of climate are always changing. Furthermore, the warmest period of the last 7,641 years in this part of Finland was around 7,000 years ago. Of the past 1,300 years, the warmest 250 year period was from AD 931-1180, the so called Medieval Warm Period. The coldest 250 year period was from AD 1,601-1,850, the so called Little Ice Age. The 20th century was relatively warm, particularly in the first half. The study shows that Finnish summers have been cooling since 1994. Longer range forecasts from this study predict general cooling of summers over the next 30 to 50 years with warming after that, but not as warm as in the 10th through 12th centuries.
Climate is always changing and the pace of change is not accelerating. Ice is not melting at an unusual rate. Melting of the relatively miniscule 414 sq-km area of Antarctica's Wilkins ice shelf compared to the +/- I million sq-km variability in sea ice extent for the hemisphere is not dramatic evidence of climate warming around the Antarctic Peninsula. In fact, much of what is written in the Scientific American News Scan is incorrect, but typical of biased journalism as it pertains to climate science. This publication should stick to the science reporting and leave the politics to others.