Newly Identified Tipping Point For Ice Sheets Could Mean Greater Sea Level Rise

In a new study published in the journal Nature Geoscience, scientists have identified a new Antarctic ice sheet "tipping point" where slight increases in the temperature of seawater infiltrating coastal ice sheets can lead to significant ice loss due to feedback loops that expand underwater cavities and accelerate ice collapse into the ocean. This mechanism could potentially cause future sea level rise to far exceed current predictions, impacting major global cities and billions of people. The Guardian reports: The researchers used computer models to show that a "very small increase" in the temperature of the intruding water could lead to a "very big increase" in the loss of ice -- ie, tipping point behavior. It is unknown how close the tipping point is, or whether it has even been crossed already. But the researchers said it could be triggered by temperature rises of just tenths of a degree, and very likely by the rises expected in the coming decades. [...] The new research [...] found that some Antarctic ice sheets were more vulnerable to seawater intrusion than others. The Pine Island glacier, currently Antarctica's largest contributor to sea level rise, is especially vulnerable, as the base of the glacier slopes down inland, meaning gravity helps the seawater penetrate. The large Larsen ice sheet is similarly at risk. The so-called "Doomsday" glacier, Thwaites, was found to be among the least vulnerable to seawater intrusion. This is because the ice is flowing into the sea so fast already that any cavities in the ice melted by seawater intrusion are quickly filled with new ice.

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