Although various recent studies have raised alarm about ice loss in Antarctica, new research offers a hint of hope for the region. A team of researchers in Denmark and the United States has found that rising bedrock underneath the West Antarctic ice sheet could slow down the rate of ice loss by protecting it from warm seawater below.
Led by the Technical University of Denmark, an international team of researchers published their findings in Science on Thursday.
A major climate assessment published earlier this month in Nature found that ice in Antarctica is melting faster than ever before, with 219 billion tonnes of Antarctic ice lost each year. By 2100, melting ice from Antarctica is projected to contribute 15 centimetres to global sea level rise, which would drastically increase the risk of flooding in coastal cities around the world.
The new study showed that rising bedrock could protect the West Antarctic ice sheet from warm seawater causing it to melt from below. This rising bedrock “may just buy the world a few extra decades,” study author Rick Aster, a seismologist at Colorado State University, told Science Magazine.
The West Antarctic ice sheet accounts for around 25% of annual melting from land-based ice. The ice sheet’s bowl-like topography makes it especially vulnerable to destabilisation, causing the area to be of particular concern amongst scientists.
According to the study, the weight placed on Earth’s crust is reduced as ice melts, allowing the compressed rock to rise back up. GPS measurements showed that bedrock near the coast of West Antarctica was rising at a rate of about four centimetres per year – one of the fastest bedrock uplift rates ever recorded in glacial areas.
The data also showed that uplift rates are accelerating, a trend the team expects to continue into the next century. Researchers said that over the next 100 years, the bedrock could rise up to eight metres in places.
“This very rapid uplift may slow the runaway wasting and eventual collapse of the ice sheet,” Aster explained in a statement. “The uplift tends to stabilise the critical grounding line where the ice sheet loses contact with underlying bedrock or sediment and goes afloat,” thereby counteracting ice sheet collapse.
However, both the study’s authors and scientists not involved in the work cautioned that bedrock rebound will not prevent the collapse of the ice sheet in the long run. Bedrock uplift might slow down the melt rate, but “it’s not a get out of jail free card,” Ted Scambos, a glaciologist at the National Snow and Ice Data Centre in Boulder, Colorado, told Science.
The West Antarctic ice sheet contains enough water to raise global sea level by three metres if total collapse were to occur.
Bedrock uplift is “still a rather slow process compared to melting,” Ingo Sasgen, a geophysicist at the Alfred Wegener Institute in Bremerhaven, Germany, explained to Science. “If you have a very strong warming from the ocean, the ice sheet will disintegrate whatever the solid earth does.”
Aster emphasised the need for climate action to limit Antarctic ice loss and its effects. “To keep global sea levels from rising more than a few feet during this century and beyond, we must still limit greenhouse gas concentrations in the atmosphere, which can only occur through international cooperation and innovation,” he said in a statement.