Brains
A recent study from Tongji University used data from two NASA satellites to determine that the Antarctic Ice Sheet has actually gained mass between 2021 and 2023. The data also showed a steep decline in ice sheet mass over the last several decades, with a pronounced acceleration in melting that started around 2010, in line with previous studies. Though the increase in ice sheet mass might initially seem surprising given that Earth’s average temperature has been steadily rising due to anthropogenic climate change, two years of ice sheet growth is actually much more indicative of shorter timescale changes in weather, which actually are also expected in a steadily warming climate.
One key takeaway that can help contextualize a growing Antarctic Ice Sheet with rising global temperatures is the difference between weather and climate. When we talk about the weather, we are referring to what the atmospheric conditions are and what they might be for the next few hours to a few weeks from now. Climate refers to the average weather, given a long history. Think about how Utah typically gets a few hundred more inches of snow than the East Coast, but so far this season, the East Coast has been running—or skiing—circles around Utah. Looking at one of the plots from the Tongji study shown below, you’ll notice the overall trend since 2002 has been downwards, with a total mass loss of about 300 gigatons since 2002. For context, the average weight of the entire snowpack at Palisades Tahoe is in the neighborhood of 30 gigatons. In 2021 and 2022, some of the ice sheet mass is recovered, to the tune of around 3 Palisades Tahoe snowpacks. From this graph we can see that the climate in the Antarctic is changing, based on the steady decrease in ice sheet mass. But, we can also see that there are still smaller timeframe variations due to weather changes in the Antarctic, since there’s a pretty obvious two year rise in 2021 and 2022.
Ice sheets, like the big ones in Antarctica or the smaller ones at your local ski hill, change mass because of a mismatch between processes that grow or shrink the ice sheet. Ice sheets gain mass through snowfall, and primarily lose mass through melting, but given the right conditions, they can also lose mass by sublimating, or transforming from solid ice crystals to water vapor. The Antarctic Ice Sheet has been losing mass for the last several decades because it has been melting into the ocean, contributing to sea level rise. It does snow in the Antarctic, but only very rarely. The Antarctic is actually one of the driest deserts on Earth, and receives an average of less than 20 inches of precipitation (liquid water equivalent) per year. So, ice sheet masses increased because 2021 and 2022 had above average precipitation. A prior study from the same group at Tongji University identified a pair of high and low pressure weather systems in the Southern Ocean that altered prevailing winds and brought more moisture into the Antarctic region than normal.
The weather in the Antarctic, much like anywhere else on Earth, depends on a rich mixture of conditions in the atmosphere and ocean, and can vary wildly year to year. Skiers will be familiar with the El Niño Southern Oscillation and the influence it can have on winter conditions in North America, and Antarctica has its own set of multiyear oscillations that can influence weather in the region, including the Indian Ocean Dipole, the Atlantic Multi-Decadal Oscillation, and the Interdecadal Pacific Oscillation, along with El Niño. With the right alignment of conditions, a few extra huge storms bringing moisture to the Antarctic can result in much larger seasonal snowfall, and even a gain in ice sheet mass.
Of course, weather does not happen uniformly throughout the southern continent, and the data on ice sheet mass change in different parts of the continent reflects that. The Amundsen Sea Sector (ASS) has seen catastrophic melting, with no increase in 2021 and 2022, whereas Dronning Maud Land (DML), Enderby Land (EL), and Kemp Land (KL) have all seen steady gains since the early 2000s, fueled by more frequent atmospheric rivers. Other satellite studies have confirmed more pronounced snowfall in Dronning Maud Land and neighboring areas and have connected the increase in snowfall to warming ocean temperatures in the tropics, disrupting weather patterns typical of the last several centuries.
Anthropogenic climate change and the steady warming of our planet will lead to more chaotic and more intense weather patterns all over the world. The Antarctic and its vast ice sheet is intimately connected with many of the feedback mechanisms of the atmosphere and oceans, and will also be subject to changing weather patterns. While these changes to our climate play out, year to year conditions will intermittently reflect worst case scenarios or conditions reminiscent of a century ago as the changing climate interacts with the other multiyear and multidecade climate patterns that influence weather on Earth. Though the effects of climate change may not always be readily apparent, careful study of critical places like the Antarctic can deepen our understanding of what is to come, as well as remind us of what is at stake if climate change continues unabated.
More From Zach Armstrong:
- East Coast Enjoys Historically Deep November While West Waits For Snow
- Inside Wisconsin’s Famous Birkebeiner Ski Marathon, One of the World’s Largest Cross-Country Races
- Trump’s Plan to Allow Drilling for Oil in the Arctic is Met With Limited Interest
- History with SnowBrains: The Incredible Notes from a Swiss Avalanche Researcher’s Travels to Western USA in 1949
- Sierra Nevada Resiliency Team Enters Second Season Supporting Ski Patroller Mental Health Across California and Nevada
