Although experts believe that global warming will raise the planet's oceans over the next few decades, some have pointed to heavier snowfall over the continent of Antarctica as a potential factor to put the brakes on this process. However, University of Washington researchers are now saying that this might not be the case.
Warmer air holds more moisture, which creates more snow inland and, according to climate model projections, will help to slightly rebuild the glacier. The authors of the current paper examined data from the West Antarctic Ice Sheet Divide ice core to shed light on the variation in the continent's snowfall over the past 31,000 years.
"It's allowed us to look at the snow accumulation back in time in much more detail than we've been able to do with any other deep ice core in Antarctica," said T.J. Fudge of the University of Washington and lead author of the study. "We show that warmer temperatures and snowfall sometimes go together, but often they don't."
The team discovered that prior to 8,000 years ago, as Earth was emerging from its last ice age, air temperatures shot up without any indication of an increase in snowfall.
"Our results make it clear that we cannot have confidence in projections of future snowfall over Antarctica under global warming," said Eric Steig, a University of Washington professor and co-author of the study.
Despite climate models suggesting that warming temperatures will increases future snowfall in Antarctica, the new data points to temperature as an unreliable indicator of this process.
"Depending on what part of the record you look at, you can draw different conclusions," Fudge said. "During some of the more abrupt climate changes, from when we had ice sheets to our current climate state, there's actually no relationship between temperature and snowfall."
The team believes that the variation in the relationship could stem from atmospheric patterns such as winds, which play a big role in the temperature of Antarctica and its sea ice, especially on shorter timescales.
"For sea-level rise, we're not really interested in what happens over thousands of years," Fudge said. "We're interested in what happens over the next few hundred years. At that shorter timescale, the variability in how the storms reach the continent matters much more than a few degrees of warming."
The current data will help scientists better understand the effect of winds on Antarctic weather and its connection to sea-level rise.
"By getting models to better capture the variability in our snowfall record, we actually will get a better idea of how the warm ocean is going to interact with the ice sheets at the edge, and those will have an even bigger impact on sea level, eventually," Fudge said.
The findings were published in the April 28 issue of the journal Geophysical Research Letters.
