Cullather contributes to large-scale study about Antarctica’s ice loss

By Teri West

Eighty-four scientists contributed to a study that gained global publicity after its recent publication in Nature. Headlines and news alerts reported on the grave findings: Antarctica’s ice loss has been accelerating rapidly.

ESSIC associate research scientist Richard Cullather, who studies the ice sheet and was one of the 84 participating scientists, wasn’t surprised by the report’s media attention. Though it was his first time participating in such a large study, he found it to be a highly organized process and attention-getting given the number of scientists involved.

Cullather has been studying ­­­­the polar regions since 1994 and collects data on ice sheet mass balance using a technique called the input-output method. It measures input of mass onto the ice sheet through snowfall and output from melting to determine an overall change.

The input-output method is one of several ways that scientists measure ice sheet mass, but when used in isolated studies, different metrics and time periods make it difficult to draw uniform conclusions. The sheer size of Antarctica further complicates its study.

“The ice sheet is 1.5 times the size of the continental U.S.,” Cullather said. “That big size creates some issues for understanding overall trends.”

The Ice Sheet Mass Balance Inter-comparison Exercise (IMBIE) was created in 2011 to tackle the challenges of studying ice sheet mass. It brings together scientists from around the world who use different methods of measurement to create large-scale studies that work with standardized metrics. The new study, which estimates ice mass for every year between 1992 and 2017, is the largest yet.

It found that in those 25 years, melting raised sea levels by 7.6 millimeters. Forty percent of that increase, however, occurred in just the last five years.

“This has to be a concern for the governments we trust to protect our coastal cities and communities,” Andrew Shepherd, a professor at the University of Leeds who led the study, said in a press release.

According to Cullather, the study’s outcome suggests there is much more to learn about Antarctica’s evolution, which is particularly important in response to future loss projections. He also notes the importance of studying the potential causes of mass change, such as snowfall deviations or the impact of sections of the sheet connected to the ocean floor.

There will also be a similar study conducted about Greenland, Cullather said.

Cullather is currently working on several NASA-funded projects related to the ice sheet. In one he is fine-tuning NASA’s snowfall estimates for the region. He is also trying to project changes of the ice sheet using models that analyze the flow of ice into the ocean.

Scientists have been starting to give more attention to the impact of melting ice sheets on sea level rise in recent years, Cullather said.

“It appears that the ice sheets are beginning to make larger and larger contributions to sea level,” he said.