At first glance, it seems like the news that snow falling over Antarctica has been steadily increasing over the last century is a good thing. But start to delve a little deeper and you’ll realize that this is a worrying sign that the climate is slipping out of kilter.
It has long been predicted that as the climate slowly heats up, there would be more snowfall over the southern continent as a warm atmosphere holds more water and thus produces more precipitation. It was therefore thought that any ice loss also caused by a warming planet would be more than balanced out by the rise in snowfall. But worryingly this doesn’t seem to be the case.
As snow lands on Antarctica, it builds up in massive layers that are slowly but surely compressed as fresh snow lands on top. Over time, this compressed snow forms the massive ice sheets that cover the continent. By taking 79 ice cores from across Antarctica, researchers have therefore been able to reconstruct exactly how much snow has been falling since the 1800s.
“When ice loss is not replenished by snowfall then sea level rises,” said lead author Dr Liz Thomas. “Satellite observations give us a picture going back around 20 years. [But] analysis of the ice core records allows us to reconstruct snowfall over several hundred years.”
This data has shown that on average over this period there has been an increase in snowfall of a not insignificant 10 percent. This equates to some extra 272 billion tonnes of snow every year, which is equivalent to around twice the volume of the Dead Sea. But while this sounds like a good thing, helping to slow the rise in sea level, there are some concerning findings in the study, which was presented at the European Geosciences Union General Assembly this week.
The greatest increase in precipitation has been around the Antarctic Peninsula, which is also experiencing the greatest increases in temperature, and the two are likely linked. As the sea ice surrounding the peninsula melts, it increases the amount of open water, which in turn increases the moisture in the air and so leads to more snowfall. The changes in ocean currents due to the loss of ice also means that more warm water passes by the region, which also increases evaporation.
So while the increase in snow has had a modest impact on the rising sea levels, slowing it by a fifth of a millimeter, this has been overwhelmingly been counteracted as ice sheets continue to slide into the sea at an ever-increasing rate.
