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Annual Public Lectures Series > Robert Bindschadler

Scientists and Journalists:
Getting the Point Across
June 9-13, 2008

Friday, June 13, 11 a.m.
Slippery When Wet
Robert Bindschadler, Chief Scientist, Hydrospheric and Biospheric Sciences Laboratory, NASA Goddard Space Flight Center

Summary

Robert Bindschadler studies the dynamics of ice sheets in Greenland and Antarctica. In recent years, he explained in his lecture for the 2008 Metcalf Institute public lecture series, scientists have become increasingly alarmed by the rate at which these ice sheets have been melting due to climate warming.

In his presentation, Slippery When Wet, on June 13, 2008, at the URI Graduate School of Oceanography, Bindschadler explained that tracking changes is important because ice sheet melt contributes significantly to sea level rise. At present, the rate of sea level rise has risen from two millimeters per year to over three millimeters per year. Even though exact estimates are uncertain, Bindschadler stated that there is little doubt that one meter of sea level rise will occur by the end of the century.

Regarding the exact response of ice sheets to climate change, scientists have been debating various outcomes. Bindschadler explained that warmer air temperatures would likely result in increased snowfall, which would quickly help to thicken the ice sheets. However, warmer air temperatures would also contribute to melting. Warmer ice tends to flow faster, which over time would result in ice breaking off in chucks and flowing away from the larger sections.

Models can help climate scientists to understand how climate shifts might contribute to the growth or shrinkage of the ice sheets. For example, decades ago Greenland's ice sheet was in equilibrium, meaning that the accumulation of snow and ice equaled melting and ice flow. Although the center is currently thickening, climate models predict that climate change would only cause about a ten percent increase in thickening. At present, scientists have observed increased melting around the edges, and models estimate that this could increase by 50 percent due to climate change.

Climate models predict a potential 100 percent increase in the acceleration of the retreat and thinning of outlet glaciers. In fact, Bindschadler noted with concern, a 210 percent increase in melting of outlet glaciers in Greenland has already been observed.

As referenced in Bindschadler's presentation title, water is one of the most important factors that influences ice sheet melting. For example, in the summertime, water from melting snow and ice funneled into rivers eventually makes its way underneath the ice. This causes basal lubrication, which helps the ice to flow faster and contributes to ice sheet shrinkage. In contrast to glaciers, which are relatively fast moving, the ice in between glaciers is slow moving and can be greatly accelerated by basal lubrication.

Ice sheet disintegration has been occurring recently at unprecedented rates. Bindschadler displayed alarming satellite images of the disintegration of Larsen B ice shelf in Antarctica, which disappeared in only six weeks. Events like these are preceded by very warm summers. Because there is such a large volume of water from increased melting, the water seeps into cracks on the ice shelf. Water, heavier than ice, acts like a powerful wedge and forces the cracks apart, thus breaking up the ice.

Glacier retreat is a problem that scientists have been studying. Bindschadler spoke about a glacier in Greenland that has been naturally retreating for over a century. However, the glacier has retreated the same distance in the past five years that used to take 50 to 60 years.

Bindschadler spoke of various hypotheses regarding other possible effects of climate change that could accelerate ice sheet melting. One links changes in weather with ocean circulation which would bring warmer water to the bottom of the ice sheet in Antarctica.

Although some consequences of climate change are uncertain, Bindschadler illuminated the certainty that impacts to the ice sheets are already underway and that we should brace for undoubted future sea level rise.

Bio

Robert Bindschadler is a Chief Scientist of NASA's Hydrospheric and Biospheric Sciences Laboratory, a Senior Fellow of the Goddard Space Flight Center, a Fellow of the American Geophysical Union, and a past President of the International Glaciological Society. He maintains an active interest in the dynamics of glaciers and ice sheets, primarily on Earth, investigating how remote sensing can be used to improve our understanding of the role of ice in the Earth's climate. As the leader of 15 Antarctic field expeditions, he has extensive first-hand knowledge of the hazards and challenges of working in the Antarctic environment. Because of his extensive work in Antarctica, he has both an Antarctic glacier and an ice stream in West Antarctica named after him. Other research has taken him to Greenland and various glaciers throughout the world. During his 27 years at Goddard, he has developed numerous unique applications of remote sensing data for glaciological research. He has testified before Congress and briefed the U.S. Vice President on the issue of ice-sheet stability and served on many scientific commissions and study groups as an expert in glaciology and remote sensing of ice. He has published over 140 scientific papers, numerous review articles, and has appeared on television, radio and is often quoted in print media commenting on glaciological impacts of the climate on the world's ice sheets and glaciers. Bindschadler also co-authored the IPCC report, which was receivly awarded the Nobel Peace Prize.

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July 31, 2008