January 31, 2006

Does Global Climate Change Affect the Glaciers in Alaska?

Submitted by Cruise West Exploration Leader- Peter Rumm

Nothing is more anticipated by our guests, returning officers and crew than a to visit one of the most dramatic places in all of North America, Tracy Arm Fjord and its' two stunning Sawyer Glaciers at its terminus. I have been making this pilgrimage since 1998 with guests, however,  this was the first season anyone could remember that for weeks, even months we could not reach either of these two glaciers. In years past, the Sawyer Glacier was clear of ice and we had no trouble safely viewing it from a 1/4 mile.   In 2005, South Sawyer Glacier was visible but only from a distance, with so much ice calving off the face, and breaking off the submerged bottom that it completely choked off the entrance preventing a close approach. It was not until July, when I was on the Sheltered Seas that Captain Mike managed to squeeze up to the face. We let our guests know that they were the first boat of the season to get as close as we did. What is so interesting from a naturalists point of view, is that this glacier has retreated unevenly over two miles in the past two years! Why is this glacier retreating so fast and calving off so much ice? One instantly asks if it has anything to do with climate change?

The earth's climate history is very complex and full of dramatic changes on extraordinary time scales completely outside of the human experience and on very small time scales within the human experience. Human life spans and recorded history are minuscule when compared to geologic or climatic change. Scientific data is indicating that humans have begun to influence the climate via industrial green house gases. A process that most likely started slowly with the industrial revolution. The outcome of these emissions is thought to be most significantly detected in the temperatures recorded in the atmosphere, oceans surface water and also the chemical compositions of both. Some of these changes can be detected with a marked increase in temperature, it is however possible to see negative feedbacks causing a decrease in temperature. That is why it is important to refer to man's potential effects on the climate as “change” and not necessarily always “warming.”

Throughout the earth's 4.5 billion year history, it is thought that development of ice sheets on the polar caps is a rare event, however the appearance and disappearance of these ice sheets occurs over million of years. In our “modern times” glaciers around the world have been receding and advancing since the end of the last great ice age around 12,000 years ago. Many glaciers in Alaska have been receding since before the industrial revolution, some are still advancing today. It is a continual challenge for scientists to make distinct connections to mans influences on the climate, oceans and glacial recession, when they can not separate what the natural fluctuations would have been without mans influence. There is however, mounting evidence that man is potentially affecting the rhythms of glacial activity in Alaska and throughout the world. Glaciologists found that the 1990’s have shown almost double the rate of glacial thinning when compared to the past forty years. This combined with increasing atmospheric and more importantly ocean temperatures has lead to the current state of alarm amongst most scientists.

For more information about melting glaciers please visit: The National Snow and Ice Data Center

Posted by Peter on January 31, 2006

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