Scientists from the British Antarctic Survey found that warm ocean water is seeping beneath the ice sheet at its “grounding line” — the point at which the ice rises from the seabed and starts to float — causing accelerated melting which could lead to a tipping point, according to the report published Tuesday in the journal Nature Geoscience.
A tipping point refers to the threshold at which a series of small changes accumulate to push a system beyond a point of no return.
The melting works like this: relatively warm ocean water opens cavities in the ice, allowing more water to seep in, which causes more melting and larger cavities to form, and so on.
A small increase in ocean temperatures can have a very big impact on the amount of melting, the study found. As climate change heats up the oceans, the process speeds up.
“You get this kind of runaway feedback,” said Alex Bradley, an ice dynamics researcher at BAS and lead author of the paper. It behaves like a tipping point, he told CNN, “where you can have a very sudden shift in how much melting is happening in these places.”
This tipping point would play out through a faster flow of ice into the oceans, in a process not currently included in models of future sea level rise, Bradley said, suggesting “our projections of sea level rise might be significant underestimates,” he added.
The implications wouldn’t be felt immediately, according to the study, but would see a higher rise in sea levels accumulating over tens and hundreds of years, threatening coastal communities around the world.
The study does not give time frames for when the tipping point might be reached, nor does it give figures for how much sea level rise can be expected. But the region is hugely significant: the Antarctic ice sheet already sheds an average of 150 billion metric tons of ice every year and, in its entirety, it holds enough water to raise global sea levels by around 190 feet (around 58 meters).
Read more at CNN
