Antarctic ice sheets may be melting faster, study says

Climate change -induced warming of the atmosphere and oceans is increasing.

The rate at which Antarctica ‘s ice shelves are melting , jeopardizing their ability to slow down the flow of the ice sheet, one study says. ice into the ocean.

A new model from researchers at the California Institute of Technology (Caltech) suggests that Antarctica ‘s ice shelves may be melting at a faster rate.

This will contribute to a faster rise in sea level, as published in the journal ‘Science Advances’ .

The model takes into account an often overlooked narrow ocean current along the coast of Antarctica  and simulates how fast-flowing freshwater, melting from ice shelves, can trap warm, dense ocean water. at the base of the ice, causing it to heat up and melt even more.

Ice shelves are outcrops of the Antarctic ice sheet each several hundred meters thick, found where ice protrudes from the land and floats on the ocean. They act as a protective buffer against continental ice, preventing the entire ice sheet from flowing into the ocean, which would dramatically raise global sea levels.

However, warming of the atmosphere and oceans caused by climate change is increasing the rate at which these ice shelves are melting, jeopardizing their ability to slow the flow of the ice sheet into the ocean. .

“If this mechanism we’ve been studying is active in the real world, it may mean that ice shelf melt rates are 20 to 40 percent higher than predictions from global climate models, which typically don’t.” can simulate these strong currents near the Antarctic coast,” says Andy Thompson, professor of environmental science and engineering.

More dramatic changes

In this study, led by lead researcher Mar Flexas, researchers focused on one area of ​​Antarctica : the West Antarctic Peninsula (WAP). Antarctica is roughly disk – shaped, except that the PAB protrudes from the high polar latitudes into lower, warmer latitudes. It is here that Antarctica experiences the most drastic changes due to climate change.

The team had previously deployed autonomous vehicles to this region, and scientists have used data from instrumented elephant seals to measure the temperature and salinity of water and ice.

The team’s model takes into account the narrow Antarctic Coastal Current that runs counterclockwise across the entire Antarctic continent, a current that many climate models don’t include because it is so small.

“The large global climate models do not include this coastal current, because it is very narrow: it is only about 20 kilometers wide, while most climate models only capture currents of 100 kilometers or more,” explains Flexas. So there’s a chance those models might not represent future melt rates very accurately.”

The model illustrates how freshwater melting from ice in the PAO is carried by the coastal current and transported across the continent. The less dense fresh water moves quickly near the ocean surface and traps the relatively warm salty ocean water against the bottom of the ice shelves. This causes ice shelves to melt from below.

Ice shelf loss acceleration

Thus, increased meltwater in the PAO can spread climate warming through the coastal current, which in turn can also intensify melting even on West Antarctic ice shelves thousands of kilometers away. the peninsula.

This distant warming mechanism may be part of the reason why the volume loss of the West Antarctic ice shelves has accelerated in recent decades.

“There are aspects of the climate system that we are still discovering,” says Andy Thompson, professor of environmental science and engineering. “As we advance our ability to model interactions between the ocean, ice shelves and the atmosphere, we can make more accurate predictions with better uncertainty constraints. We may need to revise some of the sea level rise predictions in the next few decades or the next century – that’s work we’ll do in the future.”

(With information from Europe Press)