According to a landmark study published in Nature on 13/065/18, Antartica has lost an incredible 2.7 trillion tonnes of ice since 1992. The study further suggests that if climate change continues unchecked such ice-loss could begin to reshape Earth’s coastlines.
Even more concerning than the sheer amount of mass lost is the suggestion that a whopping two-thirds of this loss occurred in the last five years. This marks an increase in the speed of the melting of land-based ice in Antartica by a factor of three. Prior to 2012 Antartica lost approximately 76 billion tonnes annually. That figure has now soared to 219 billion tonnes.
The study authored by a consortium of 84 scientists should dispel any questions regarding the shrinking of the continent’s kilometres thick land ice casing. It also presents a stark warning of the threat facing low-lying coastal towns and cities.
Unlike ice which already floats in the sea, land-based ice sheets have the potential to cause major sea level rise when they melt through melt-water run-off and ice breaking free and running into the sea. Scientists were involved in a heated debate as to whether Antartica had been losing more ice through these channels than it gained through snowfall or whether the two actors balanced. This study, which examined over two decades of satellite data from 24 different space-based surveys to reach its conclusions should conclusively end such debates and leave scientists in little doubt that the outflow of ice in the region is greater than the inflow.
The study also manages to pinpoint the location of the most concern. Most of the ice lost over the last 25 years has originated from West Antarctica. This area has been the most vulnerable to warming and the Antartic Penisula has seen 6,500 kilometres of ice shelves sheer off into the sea between 1995 and 2017.
In addition to this two major glaciers, Thwaites and Pine Island have accelerated in their progress seaward and are now considered unstable. These glaciers currently hold back ice masses further in-land from finding their way to the ocean.
The 2.7 trillion tonnes of ice lost since 1992 is estimated by the team to have added approximately 8 millimetres to sea level. This means that if the current trend was to continue Antarctica could become the single biggest source of sea-level rise overtaking other sources such as runoff from the Greenland ice-sheet and mountain glaciers and the thermal expansion of ocean water.
The paper’s co-author, Eric Rignot of NASA’s Jet Propulsion Laboratory had stark words of warning for global leadership in the wake of these findings: “We now have an unequivocal picture of what is happening in Antartica,” Adding “We view these results as another ringing alarm for action to slow the warming of our planet.”
The study has been praised by other climate scientists. Martin Siegert of the Imperial College London called the outcome of the study “Deeply concerning,” Siegert continued “If we aren’t already alert to the dangers of climate change, this should be an enormous wake-up call.”