A recent study conducted by UC San Diego’s Scripps Institution of Oceanography reveals that the flow of meltwater beneath Antarctic glaciers is causing an acceleration in ice loss. This phenomenon, known as subglacial discharge, could significantly impact predictions of global sea-level rise, especially if greenhouse gas emissions continue to rise.
Through simulations, researchers found that meltwater flowing beneath Antarctic glaciers could increase sea-level rise by 15% by the year 2300. These findings suggest that future projections should take into account the effects of subglacial discharge.
The study, published in Science Advances and funded by the National Science Foundation, NASA, and the Cecil H. and Ida M. Green Foundation for Earth Sciences, used a new Antarctic ice sheet model to demonstrate that meltwater flowing from beneath glaciers is causing them to lose ice at a faster rate.
The model showed that this effect could make a significant contribution to global sea-level rise, particularly under high greenhouse gas emissions scenarios. Currently, major sea-level rise projections, such as those by the Intergovernmental Panel on Climate Change (IPCC), do not consider this additional ice loss caused by subglacial discharge. If it is found to be a major driver of ice loss across the entire Antarctic ice sheet, current projections may underestimate future sea-level rise.
The lead author of the study, Tyler Pelle, emphasized the importance of accurate sea-level rise projections for coastal communities. He stated that millions of people live in low-lying coastal areas and accurate projections are necessary for adequate preparation.
The study focused on two glaciers in East Antarctica, Denman and Scott, which together hold enough ice to cause nearly 1.5 meters (5 feet) of sea-level rise. The model found that under a high emissions scenario, subglacial discharge increased the sea-level rise contribution of these glaciers by 15.7% by the year 2300.
These glaciers are situated on a continental trench over two miles deep. Once their retreat reaches the steep slope of the trench, their contribution to sea-level rise is expected to accelerate dramatically. With the added influence of subglacial discharge, the model indicated that the glaciers reached this threshold around 25 years earlier than they would have without it.
Jamin Greenbaum, a co-author of the study, highlighted the importance of including subglacial discharge in ice sheet models. He stated that the findings of the study should serve as a wake-up call for the modeling community, highlighting the need to account for this process in future projections.
The study also emphasized the significance of reducing greenhouse gas emissions in the coming decades. The researchers found that in a low emissions scenario, the glaciers did not retreat into the trench, avoiding further contributions to sea-level rise.
The study sheds light on the understudied role of subglacial discharge in accelerating sea-level rise and underscores the importance of reducing emissions to mitigate the consequences of climate change.
