Brenda Hall – Scientists

Brenda HallBrenda Hall
University of Maine,
Climate Change Institute

What questions related to the Arctic are you trying to answer?/How will those answers help us understand more about our world? Our main interest is the cause and characteristics of abrupt climate change. Our approach towards this problem is to look at past episodes of rapid climate change and to try to figure out what happened and why. This gives us insight into climate change and helps us make predictions for the future. It allows us to determine what natural climate variability looks like and how that might differ from man-made warming. It also gives us insight into the possible consequences of man-made warming.

How are you trying to find the answers to those questions? We are taking several different approaches, but all of them center on looking at the history of glaciers in the Arctic, in particular, Greenland. Glaciers respond very sensitively to climate change, and so we can use the record they leave behind to reconstruct past changes in ice extent and even temperature variations. A lot of work involves making maps of sediments that the glaciers left behind when they were larger than today. We also look for ways to date these sediments, using chemical techniques, so that we know exactly when the glaciers were in certain spots.

Recount for us one of your field days. Most of our days are spent mapping sediments and collecting material for radiocarbon dating. For this method of determining age, we need to find something that has carbon in it – in East Greenland, this means shells. These shells once lived on the shores of the fjord, but over time, the land has risen, leaving these shells as much as 100 m above present sea level. A lot of our time is spent looking at these old ocean sediments and trying to find shells. Our typical days are spent walking long distances – more than 10 miles normally, searching for shells constantly as we walk. While there are places with lots of shells, there are many more places that don’t have any and searching is a very time-consuming, often frustrating process.

I remember the first day ever we were in the field in Greenland. We had arrived late the night before and were very eager to get out and see the new area. We set off walking after breakfast with the goal of seeing some of the key spots we had seen on our air photographs. We crossed the meltwater stream early in the morning and walked all day. In the eagerness to see things, we didn’t keep a close eye on the time – we knew we didn’t have to worry about it getting dark. By the time we made it back to the meltwater stream, it was 10 PM. Only this time the stream was a lot higher, since the glacier had been melting all day. It took us well over an hour of wading from bar to bar to find a place where we could cross. I think we got into camp that night – or the next morning – at 1 AM, some twenty miles later and too tired to eat supper. Although I’d like to say we learned a lesson, this really set the pattern for our field work in Greenland – very long days! This allowed us to take advantage of the limited time we had in the field. We were, however, a bit more careful about the meltwater streams in the future!

What do you find most rewarding about being a scientist? I like the challenge of figuring out a problem and finding out things that no one has known before.


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