Researchers testing heat in the West Antarctic ice sheet have found a surprisingly high level of geothermal heating. Their results, published in Science Advances on July 10, could help scientists to better understand and predict the rate at which the ice sheet is melting.
Geothermal heat is generated deep within the Earth and radiates upward. The heat detected, 285 milliwatts per square meter, would seem miniscule to most. It is roughly the equivalent of one LED Christmas light per square meter. However, in the frigid cold of the Antarctic it can have a considerable impact.
According to Andrew Fisher of UC Santa Cruz, lead author of the paper, the heating is not sufficient to account for the level of melting found in the West Antarctic.
“The ice sheet developed and evolved with the geothermal heat flux coming up from below–it’s part of the system. But this could help explain why the ice sheet is so unstable. When you add the effects of global warming, things can start to change quickly,” said Fisher in a statement.
The author also cautions that the heat reading was only taken at a single location. Assuming that it is indicative of temperatures in the region, a higher than expected heat reading could help to explain the presence of lakes beneath the ice sheet and the rapid flow of ice streams.
“This is the first geothermal heat flux measurement made below the West Antarctic ice sheet, so we don’t know how localized these warm geothermal conditions might be. This is a region where there is volcanic activity, so this measurement may be due to a local heat source in the crust,” said Fisher.
The warmer than anticipated temperatures could also help to explain the diversity of microbial life found in subglacial lakes, as reported in the journal Nature last year.
Coauthor Slawek Tulaczyk, also of UC Santa Cruz, points out that a more thorough understanding of geothermal cycles of heating will be essential to creating accurate computer models of the West Antarctic. These models will help scientists to better understand the overall climate and estimate the region’s contribution to sea level rise.
“It is important that we get this number right if we are going to make accurate predictions of how the West Antarctic ice sheet will behave in the future, how much it is melting, how quickly ice streams flow, and what the impact might be on sea level rise. I waited for many years to see a directly measured value of geothermal flux from beneath this ice sheet,” said Tulaczyk.
A large part of the reason that the temperature was only taken in one location is the difficulty in getting such readings at all. Getting the temperature reading required boring through deep sheets of ice in an inhospitable climate. It also required a special instrument, developed by Scott Tyler at the University of Nevada, Reno which was left in the bore hole as it refroze.
The measurements were taken as part of a project funded by the National Science Foundation called WISSARD (Whillans Ice Stream Subglacial Access Research Drilling).
