by Phillip Manning ~ August 6th, 2013
Five years of planning went into a drilling project in the heart of the Alaska Range. The scientists involved weren’t drilling for oil, however. They are part of a team studying glacier ice to better understand how the climate has changed over the last thousand years.
Dr. Erich Osterberg is an Assistant Professor of Earth Science at Dartmouth College. He and a team of professors and students from Dartmouth, the University of New Hampshire, and the University of Maine spent a month and a half drilling on Mt. Hunter this summer in order to obtain glacial ice cores from as far down as 700 feet. The samples were obtained using a solar and wind powered drill, and were then packed and flown out of the mountains. The ice will be used to study past, present, and future climate change. Osterberg says that central Alaska has been warming, both due to natural cycles and greenhouse gas. He says that some of those natural cycles are decades long, meaning that weather records, which only go back for about a century, don’t provide enough historical data.
“We really need these ice cores to get further back in time to understand both how the climate cycled naturally in the past, but also what caused those cycles. That puts us in a much better position to understand what’s happening there today, which is pretty dramatic in some cases, and some of the most dramatic warming that we’re seeing anywhere in North America.”
To better understand the cycles and patterns that control Alaska’s climate, Osterberg and his team will be carefully analyzing the ice cores to see when the climate changed. He says that the ice has layers, much like the rings on a tree trunk, that help determine how old each core sample is. The team will be studying the ice all the way down to the molecular level to determine what , other than water, is present.
“Our specialty is looking at the chemistry of the ice in the core. That includes anything that falls on the glacier, like dust, volcanic ash, or sea salt that’s blown up from the Gulf of Alaska in these storms. We can see how much of that fell on to the glacier in the past, and that tells us, for example, how strong those storms were. There’s a very good relationship between how strong the storms are that are hitting Talkeetna and how much sea salt is getting blown in…”
Osterberg hopes the team’s research into the history of natural climate cycles will give them clues as to what controls them, and what impact continued natural warming, as well as greenhouse gases, will have in the future. In addition, he believes the study will give insight to how Alaska’s glaciers respond to climate change.
“We’re going to be investigating how the glaciers in Denali Park advanced and retreated over the last thousand years as well. We’re going to have climate data from the ice cores, and then we’re going to see how the glaciers responded by looking at where their positions moved through time. We’ll be able to put those into our glacier models and our climate models and get a really good understanding of how these glaciers respond to climate change…That will allow us to predict how much they’re going to melt back in the future, and therefore how much they’re going to contribute to global sea level rise.”
The data analysis will take another two years, but afterwards, the team hopes to have a much better understanding of what controls the climate in central Alaska.