Response Time of Ice Sheets to Climatic Forcing

Dr. Anders Carlson

Collaborators:

Joe Stoner (COAS, Oregon State University), Jeff Donnelly (WHOI) Grad Students Involved; Brent Goehring (LDEO), Helen Evans (U. of Florida)

This is an on-going project (multiple) investigating the response of Northern Hemisphere Ice Sheets to climate forcing (e.g. carbon dioxide, insolation). The over arching goal is to determine how fast an ice sheet will retreat to predict the response of the Greenland and Antarctic Ice Sheets to global warming. For instance, the current carbon dioxide level (Fig. 1) has condemned us to ~20 or so meters of sea level rise (no Greenland or West Antarctic Ice Sheets).

Fig. 1. This is a graph showing the relationship between carbon dioxide concentration and sea level (ice sheet volume) relative to modern. (modified from Alley et al., 2005)

What we don't know is how fast that will happen. Current ice sheet models are incapable of simulating past rapid ice sheet retreat and are failing to predict the current acceleration of the Greenland Ice Sheet. Thus, we are circumventing the short-comings of models by using the geologic record (where there are collapses of ice sheets) to better constrain the sensitivity of ice sheets to climate perturbations. Another aspect of this research is looking at the climatic effects that occur when an ice sheet is removed. We are currently using terrestrial records (e.g. Cosmogenic Isotope dating) from the Laurentide Ice Sheet, which are indicating that this ice sheet experienced several collapses in the mid-Holocene. We have projects in the works to continue studying the Laurentide Ice Sheet along with the other Northern Hemisphere ice sheets using terrestrial and marine records.