The best and worst of journalism is surfacing on the heels of the administration’s National Climate Assessment report. The catastrophic melting of polar icecaps — predicted several times, as early as 1922 — has not yet materialized. Recent reports contain rehashes of earlier ones alleging imminent collapse of the West Antarctic ice sheet while ignoring other studies that offer more rational, if less dramatic, explanations.
Erosion of Antarctica’s glaciers has proceeded unabated since the end of the last ice age and continued slowly through the past century to the present day. Passage of time, even millennia, would be required before enough ice melted to raise sea levels by the 12 to 13 feet mentioned in recent news accounts, assuming the rate of about 7 inches per century remains constant.
There is reason to expect another intervening period of sustained cooling could interrupt or reverse the process, as has happened during past millennia. Recent changes in sun spot activity, signaled in Sun Cycles 23 and 24, may serve as a harbinger of change much sooner than climate alarmists realize.
Carbon dioxide added to the atmosphere by man’s activities since 1950 (the post-World War II industrial expansion) has contributed little to global-scale warming compared with natural processes that dominate climate. Increasing carbon dioxide and slowly melting ice do not signal the imminent destruction of the West Antarctic Ice Shelf, as a New York Times reporter admitted in a May 12 article.
Statements suggesting man-made carbon dioxide somehow triggers high-velocity circumpolar winds over the Southern Ocean is speculative for a region already notorious for high winds and treacherous seas. (See accounts of Ferdinand Magellan and Sir Francis Drake.) The New York Times’ uncharacteristically tempered expectation of a delay in the collapse of the ice shelf into the next millennium likewise assumes current warming continues unchecked by changes in the natural order. Cyclical patterns of warming followed by cooling are very common in the geologic record, as interpreted from ice and ocean sediment core data from widely separated regions around the planet.
Recent reports indicate ice over the interior (as well as sea ice) of the Antarctic continent has increased for at least several decades, reversing or at least delaying a longer-term trend in rising seas. These observations are consistent with the idea that comparatively warmer water produces greater amounts of precipitation over the continent, helping to replenish glacial ice.
The West Antarctic Ice Shelf is grounded ice. The shelf extends over a broad bay of the Amundsen Sea (along Antarctica’s west coast) and drains glacial fields fed by the Vinson Massif — at 16,067 feet, the highest elevation in Antarctica. Because of its immense weight, the sheet rests on a bedrock platform that would be submerged under sea water absent the ice. Melting of grounded ice contributes to the volume of the oceans and thus to rising sea level. Melting of floating sea ice does not contribute to rising levels when it melts, in the sense that a melting ice cube does not raise the level in a glass of ginger ale.
The “unstoppable” melting of the West Antarctic Ice Shelf is open to discussion. Clearly, the entity or an earlier version existed during and after previous glacial periods before the last one ended about 10,000 years ago. A New York Times article notes a smaller ice sheet along the eastern side of the Antarctic Peninsula completely melted about 6,000 years ago, then reformed around 4,000 years ago. The smallest of several nearby shelves broke up in the same area in 2002, causing great consternation among alarmists.
Pessimism over continued — and allegedly accelerating — melting of the larger sheet may once again prove unwarranted. Coolings that followed each past period of cyclical warming were sufficient to reverse the effects of prior synoptic warming: The Dark Ages Cold Period followed the Roman Optimum, and the Little Ice Age followed the Medieval Optimum.
Diligent efforts at regional climate modeling by statistical or mathematical methods have disappointed their practitioners. Even global climate models, together costing more than $1 billion, failed to anticipate the nearly 18-year pause in warming since 1996-97. They fail to replicate, with reasonable accuracy, the temperature record beginning in 1950. In the language of the climate scientists, the models lack “skill.”
These failures spring from an inadequate understanding of the physical processes (forcings and feedbacks) controlling coupled interactions taking place in dynamic, chaotic systems. Complex processes determine the weather in the near-term and climate over decades and centuries.
William D. Balgord, geochemist and consultant, heads Environmental & Resources Technology Inc. in Middleton, Wis.