A newly identified tipping point for the loss of ice sheets in Antarctica and elsewhere could mean future sea level rise is significantly higher than current projections.

A new study has examined how warming seawater intrudes between coastal ice sheets and the ground they rest on. The warm water melts cavities in the ice, allowing more water to flow in, expanding the cavities further in a feedback loop. This water then lubricates the collapse of ice into the ocean, pushing up sea levels.

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 behaviour.

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.