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Ice melt projections may underestimate Antarctic contribution to sea level rise

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Ice melt projections may underestimate Antarctic contribution to sea level rise
Thwaites Glacier, Antarctica, pictured in 2019. Credit: NASA

Fluctuations in the weather can have a significant impact on melting Antarctic ice, and models that do not include this factor can underestimate the global impact of sea level rise, according to Penn State scientists.


“We know ice sheets are melting as global temperatures increase, but uncertainties remain about how much and how fast that will happen,” said Chris Forest, professor of climate dynamics at Penn State. “Our findings shed new light on one area of uncertainty, suggesting climate variability has a significant impact on melting ice sheets and sea level rise.”

While it is understood that continued warming may cause rapid ice loss, models that predict how Antarctica will respond to climate change have not included the potential impacts of internal climate variability, like yearly and decadal fluctuations in the climate, the team of scientists said.

Accounting for climate variability caused models to predict an additional 2.7 to 4.3 inches—7 to 11 centimeters—of sea level rise by 2100, the scientists recently reported in the journal Climate Dynamics. The models projected roughly 10.6 to 14.9 inches—27 to 38 centimeters—of sea level rise during that same period without climate variability.

“That increase alone is comparable to the amount of sea level rise we have seen over the last few decades,” said Forest, who has appointments in the departments of meteorology and atmospheric science and geosciences. “Every bit adds on to the storm surge, which we expect to see during hurricanes and other severe weather events, and the results can be devastating.”

The Antarctic ice sheet is a complex system, and modeling how it will evolve under future climate conditions requires thousands of simulations and large amounts of computing power. Because of this, modelers test how the ice will respond using a mean