Subglacial meltwater flowing beneath Antarctic glaciers could accelerate retreat: Study

Meltwater flowing out to sea from beneath Antarctic glaciers, or subglacial discharge, could be making m lose ice faster, researchers have found in a new study. Modelling influence of this subglacial discharge on retreat of two glaciers in East Antarctica, researchers found that it raised glaciers' contribution to sea-level rise by 15.7 per cent -- from 19 millimetres to 22 millimetres -- by year 2300.

findings, relevant in a high emissions scenario featuring 20 per cent higher CO2 emissions by 2100, suggested that subglacial discharge's influence was large eugh to make a meaningful contribution to global sea-level rise, researchers at University of California San Diego's Scripps Institution of Oceagraphy in US said.

East Antarctic glaciers, named Denman and Scott, toger hold eugh ice to cause nearly 1.5 metres, or 5 feet, of sea-level rise, y said in ir study published in journal Science vances. Current models making major sea-level rise projections, including those of Intergovernmental Panel on Climate Change (IPCC), do t take into account this mechanism of subglacial discharge, researchers said.

Thus, it could mean that current projections underestimate pace of global sea-level rise in deces to come, y said. "Kwing when and how much global sea-level will rise is critical to welfare of coastal communities," said Tyler Pelle, study's le author and a postdoctoral researcher at Scripps.

"Millions of people live in low-lying coastal zones and we can't equately prepare our communities without accurate sea-level rise projections," said Pelle. In Antarctica, subglacial meltwater is generated from melting occurring where ice sits on continental bedrock.

When subglacial discharge flows out to sea it is thought to accelerate melting of glacier's ice shelf, which is attributed to ocean mixing that stirs in ditional ocean heat within cavity beneath a glacier's floating ice shelf. resulting glacial retreat can n contribute to and drive sea level rise.

reason why this mechanism of subglacial discharge is t currently considered in sea-level rise projections is because many researchers weren't sure if its localised effects were sufficiently large to increase sea-level rise globally, according to Jamin Greenbaum, co-author of study and a researcher at Scripps Institute of Geophysics and Planetary Physics.

A key takeaway of study, however, is importance of what humanity does in coming deces to rein in greenhouse gas emissions, said Greenbaum. This is because ir model found that in a low emissions scenario, glaciers did t retreat all way into trench and thus did t result in making runaway contributions to sea-level rise.

"If re is a doomsday story here it isn't subglacial discharge," said Greenbaum. " real doomsday story is still emissions and humanity is still one with its finger on button."