Climate variability

Antarctica is melting faster than models predict due to climate variability •


Decreasing ice levels in Antarctica, as well as future sea level rise, have been underestimated. In a new study by State of pennsylvania, the researchers found that existing models do not take into account climate variability, which has a significant influence on the Antarctic ice sheet.

“We know that ice caps are melting as global temperatures rise, but uncertainties remain about the extent and speed of this melting,” said study co-author Professor Chris Forest. “Our results shed new light on an area of ​​uncertainty, suggesting that climate variability has a significant impact on melting ice caps and sea level rise.”

Before accounting for climate variability, experts found that models predicted sea level rise of about 10.6 to 14.9 inches by the end of this century. When climate variability was incorporated into the models, these predictions increased to 4.3 inches.

“This increase alone is comparable to the amount of sea level rise that we have observed over the past decades,” said Professor Forest. “Every element adds to the storm surge, which we expect to see during hurricanes and other severe weather events, and the results can be devastating.”

It takes thousands of simulations to project how the Antarctic ice sheet will evolve under future climatic conditions. Scientists use the average temperature that is derived from all of these results.

However, the process mitigates peaks caused by climate variability and reduces the average number of days above temperature thresholds that can impact the melting of the ice sheet, creating a bias in the results, the scientists said. .

“If we include the variability in the simulations, we will have more hot days and more sunshine, and so when the daily temperature exceeds a certain threshold, it will melt the ice,” said Prof Forest. “If we only operate in average conditions, we don’t see these extremes happening on annual or decadal timescales. “

To study the effects of climate variability, scientists incorporated relevant atmospheric and oceanic data into a three-dimensional model of the Antarctic ice sheet. The analysis showed that atmospheric variations had a significant impact on the ice sheet with immediate effects. The variability of ocean temperatures was found to have a smaller, but significant impact.

Results from previous studies suggest that warming oceans could cause large pieces to break apart, exposing massive ice cliffs that would collapse under their own weight.

According to experts, model simulations that did not include the effects of climate variability delayed the retreat of the ice sheet for up to 20 years and underestimated future sea level rise.

“This additional melting ice will impact hurricane storm surges around the world. Additionally, for years, IPCC reports have looked at sea level rise without taking into account this additional variability and underestimated the potential impact, ”said Prof Forest. “It is important to better understand these processes that contribute to the loss of additional ice because the ice caps are melting much faster than expected. “

The study is published in the journal Climate dynamics.

By Chrissy sexton, Editor-in-chief


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