Thwaites Glacier: melting fast

The West Antarctic Ice Sheet, which holds enough water to raise global seas by several feet, is about to collapse, according to scientists from the University of Washington.

Using detailed topography maps and computer modeling, researchers concluded the ice collapse appears to have already begun.

"Previously, when we saw thinning we didn't necessarily know whether the glacier could slow down later, spontaneously or through some feedback," explains Ian Joughin, a glaciologist at the UW's Applied Physics Laboratory.

"In our model simulations it looks like all the feedbacks tend to point toward it actually accelerating over time; there's no real stabilizing mechanism we can see."

The study considered future scenarios using faster or slower melt rates depending on the amount of future warming. The fastest melt rate led to the early stages lasting 200 years, after which the rapid-stage collapse began.

The slowest melt rate kept most of the ice for more than a millennium before the onset of rapid collapse. The most likely scenarios may be between 200 and 500 years.

The melting of the Thwaites Glacier will raise sea level by nearly two feet. That glacier also acts as a linchpin on the rest of the ice sheet, which contains enough ice to cause another 10 to 13 feet (three to four meters) of global sea level rise.

The thinning of the ice in recent decades is most likely related to climate change. More emissions would lead to more melting and faster collapse, but other factors make it hard to predict how much time we could buy under different scenarios.