Published: Sun, June 17, 2018
Research | By Raquel Erickson

Trillions of tons of melting ice in Antarctica raising sea levels

Trillions of tons of melting ice in Antarctica raising sea levels

"We view these results as another ringing alarm for action to slow the warming of our planet".

Much of the East Antarctic ice sheet is land-based.

It is the most complete picture of Antarctic ice sheet change to date - 84 scientists from 44 global organisations combined 24 satellite surveys to produce the assessment.

Some studies had suggested a net gain in mass over recent decades.

This in turn is pushing global sea levels up by 0.6mm a year, three times the rate seen in 2012. But massive glaciers on West Antarctica slowly gliding seaward hold enough water to push oceans up by 3.5 metres (11 feet). Most of this loss came from the huge Pine Island and Thwaites Glaciers, which are retreating rapidly due to ocean-induced melting.

Dr. Rob Massom, a researcher at the AAD and the lead author of a Nature study on the disintegration of the Antarctic Ice Shelf, explains the process.

"In the past we've been persuaded of a narrative that sea level rise affects people in low-lying countries in the Pacific Ocean, and while that's devastating for them, it might not be a problem for a majority of the world's population", Shepherd said.

The study, by an global team of polar scientists led by Canada Research Chair Christine Dow of Waterloo's Faculty of Environment, discovered that the process of warmer ocean water destabilizing ice shelves from below is also cracking them apart from above, increasing the chance they'll break off.

DeConto said, "Emerging science is pointing to more extreme worst-case scenarios with regards to sea level rise from Antarctica, but the good news is that a reduction in emissions, in line with the aspirations of the Paris Climate Agreement, dramatically reduces the risk of flooding our coastlines in future decades and centuries".

Sea level will rise to 5 mm in one year, and it will flood cities on the coasts, causing economic losses of $1 trillion per year. "But remember for the northern hemisphere, for North America, the fact that the location in West Antarctica is where the action is amplifies that rate of sea level rise by up to an about additional 25 percent in a city like Boston or NY".

So far scientists are not comfortable saying the trend in East Antarctica will continue.

The most dramatic change was found in West Antarctica, with ice loss rising from 53 billion tons per year in the 1990s to 159 billion tons per year beginning in 2012. Since then, that figure has jumped, on average, to 219 billion tonnes. "Sea level rise for the future, it's not happening at the same rate in every part of the world... this gravity thing has a big impact". Scientists not involved with the study lauded its methodology. Researchers, including scientists from Imperial College London, compared what would happen to the ice and wildlife of the South Pole in 2070 under two scenarios: one in which lowered greenhouse gas emissions coincided with maintaining environmental regulations, and one in which emissions were allowed to rise and regulations to deteriorate, an Imperial College London press release reported. "They show no indication of being exposed to cosmic rays", said Marc Caffee, a co-author of the paper and professor of physics at Purdue University in the United States.

Overall, world sea levels have risen about 20 cm in the past century.

"If we aren't already alert to the dangers posed by climate change, this should be an enormous wake-up call", he added.

Like this: