June 25, 2009

Summer on Ice

Assistant Professor of Earth and Atmospheric Science at City College

You don’t have to be an expert in atmospheric science to know that extensive decreases in glaciers and ice caps are contributing to the world’s rising sea levels. But how and why are they melting? Therein lies my mission for the summer.

In my field of earth and atmospheric studies, we know that a major contributing factor is that the Greeland “ice sheet” has been melting at an increasing rate in recent years. And that when snow and ice melt, the water flows along the ice sheet and some of it accumulates in large ponds called supraglacial lakes. But little is know about them.

I’m traveling to Greenland to explore the lakes and the connection between their formation and the melting of Greenland’s ice sheet. I’ll be accompanied by Nick Steiner, a graduate student in earth and atmospheric studies. Our work is supported by CUNY, the World Wildlife Foundation (WWF) and NASA.

Evidence suggests that the drainage mechanism for some lakes may involve subsurface features called moulins, and that they might be responsible for the accelerated melting of the ice sheet. When a lake contains enough water to put pressure on the ice below, a crack can develop to the bottom of the ice sheet (several hundred meters thick) and drain through. The pressure can be so great that the lake empties in a matter of hours. If the water reaches the point where ice meets bedrock, it will eventually flow toward the sea along the bottom. In theory, this could cause the ice sheet to accelerate toward the sea.

Before reaching Greenland, Nick and I will spend a few days in Iceland to study some glaciers there and to train for ice climbing. Then we head to the Greenland village of Iulissat, on the west coast, for three days of final preparations. Here we’ll collect the scientific equipment we’ve shipped from New York and get it ready for our studies. The key piece is a miniature remote-controlled boat equipped with GPS, a spectrometer, an underwater videocamera and a microcomputer. It will take our measurements of the ice sheet. Before our departure from New York, we tested the boat in Central Park and found it was good to go. (See the video: http://www.youtube.com/watch?v=qRUusdEeX50 )

We will also measure the flow of water in and out of the lakes and will collect water samples for studying the water’s biological and chemical properties as well. By collecting lake depth and spectral data on the ground comparable to what is measured by satellites, we will study the differences between the two data sets, understand the errors that we have when we use satellites data and develop new approaches for quantifying how much water is stored in these lakes and if changes occurred over the past years.

We will also collect video and photographic material during the scientific expedition and will document how people live in the Arctic, their costumes and habits. This material, together with our research findings, will be incorporated into an interdisciplinary undergraduate course called Global Warming offered by the Earth and Atmospheric Studies Department at City College and in a course titled “Changing Arctic Environment” that I will teach at the CUNY Graduate Center in the fall.