Climate analysis makes sense of Antarctic puzzle

In a warmer world, scientists expect to see an increase in snowfall over the Antarctic because of higher levels of moisture in the air. This is expressed in global and regional climate models as an increase in surface mass balance (SMB) -- a term that incorporates the loss of mass in the Antarctic ice sheet through sublimation and the gain in mass due to snowfall.

However, so far -- and contrary to robust projections -- observations have failed to detect any such increase in net snow accumulation in the region in recent times. Reporting their findings in the journal Environmental Research Letters, scientists in the US have looked into this discrepancy in more detail.

"The long-term SMB trend due to global warming in recent decades is small compared to the natural variability of SMB that arises from random, chaotic variations in the weather," explained Michael Previdi of Columbia University, who performed the study together with his colleague, Lorenzo Polvani. "As a result, these random weather variations could have effectively 'masked' the global warming signal, thus preventing any long-term SMB trend from being detected in the observations."

Their conclusions are based on the analysis of 35 different climate models, which allow the researchers to quantify i) the human influence on Antarctic SMB and ii) the natural variability of SMB that arises from random, chaotic variations in the weather.

"We believe that the human influence on Antarctic SMB will become detectable within the next few decades," said Previdi. "This is of critical societal importance since increases in snowfall in the region will have a mitigating effect on future global sea-level rise."

Full details on the work can be found in the open access journal Environmental Research Letters .