As a result of coastal ocean currents, Antarctica’s ice shelves may be melting up to 40 percent quicker than previously believed, a new study warns.
Californian scientists have developed a new climate model that incorporates the influence of the Antarctic Coastal Current (ACC).
According to the experts, this restricted stream melts Antarctica’s ice shelves, which are floating platforms of ice along the Antarctic coastline.
Their model implies that ice shelf melting rates are 20 to 40 percent higher than what earlier climate models had predicted.
Ice shelves protect against the uncontrolled discharge of inland ice into the ocean, therefore their melting could eventually lead to a faster increase in sea level.
The latest study, which was published on Friday in the journal Science Advances, was led by researchers from Caltech and JPL in California.
If this mechanism we’ve been studying is active in the real world, it could mean that ice shelf melt rates are 20 to 40 percent higher than predicted by global climate models, which cannot typically simulate these strong currents near the Antarctic coast,’ said Andy Thompson, lead author of the study at Caltech.
Ice shelves are enormous floating ice platforms that link to a landmass, such as Antarctica or Greenland. Ice shelves can also be found in other polar regions, such as the Arctic.
The shelves serve as a protective buffer for the ice on the continent, preventing the entire Antarctic Ice Sheet from draining into the ocean, which would significantly raise global sea levels.
However, a warming atmosphere and oceans due to climate change are increasing the rate at which these ice shelves are melting, jeopardizing their ability to prevent the ice sheet from flowing into the ocean.
The crew focused on the West Antarctic Peninsula for their research.
Antarctica is disk-shaped, except for the peninsula, which protrudes out of the high polar latitudes and into the lower, warmer latitudes.
Here, in Antarctica, the effects of climate change are most pronounced.
The team has already deployed autonomous vehicles in this region, and scientists have measured the temperature and salinity of the water and ice using data collected by elephant seals with devices connected to them.
The researchers developed a computer model that takes into consideration the Antarctic Coastal Current, a narrow ocean current that is frequently disregarded near the Antarctic coast.
The Antarctic Coastal Current, which is the world’s southernmost current, flows counterclockwise around the whole Antarctic continent.
However, many climate models exclude the Antarctic Coastal Current due to its relative narrowness – approximately 12.5 miles (20 km).
“Most climate models only capture currents with a width of 100 kilometers or more,” said Caltech researcher Mar Flexas.
Therefore, it is possible that these models do not accurately predict future melt rates.
The computer model demonstrated how fast-flowing freshwater, melting from ice shelves, can trap dense, warm ocean water at the base of the glacier, causing the ice to warm and melt further.
It demonstrates how freshwater that melts from ice at the West Antarctic Peninsula is moved throughout the continent by the Antarctic Coastal Current.
The less thick freshwater travels fast along the ocean’s surface and traps relatively warm ocean seawater against the underside of the ice shelves, causing them to melt from below.
In essence, greater meltwater at the West Antarctic Peninsula can cause global warming via the Antarctic Coastal Current, which in turn can accelerate melting at ice shelves located thousands of kilometers distant from the peninsula.
This remote warming mechanism may be a contributing factor in the recent acceleration of volume loss from West Antarctic ice shelves.
Thompson stated, “There are components of the climate system that we are currently uncovering.”
As our ability to model interactions between the ocean, ice shelves, and atmosphere has improved, we can generate more accurate predictions with tighter uncertainty bounds.
We may need to reconsider certain forecasts of sea level rise in the coming decades or centuries; this is a project for the future.
The new findings follow a report published in Nature on Wednesday, which stated that Antarctica’s ice shelves are ‘crumbling’ and have shrunk dramatically over the past quarter-century.
The study concluded that around 12 trillion tonnes of ice had been lost over the past 25 years, which is double the previous estimate.
This week, two of the authors wrote for The Conversation that one of the causes of ice shelf retreat is the thinning of ice shelves, which is mostly driven by relatively warm seawater eroding the shelves’ bases.
