El Nino is melting ice shelf, OSU fi nds

Warm gusts of air caused by a particularly strong El Nino last year resulted in substantial melting of an Antarctic ice sheet twice the size of California, according to a new study led by Ohio State University researchers.

The findings are not only worrisome for the stability of the floating ice sheet, which affects the flow of about one- third of the ice from west Antarctica into the ocean, but rising ocean levels as well.

If the Ross ice shelf completely melted, it would raise ocean levels by 11 feet, according to the research team that included scientists from the University of California- San Diego.

The research, based on satellite data, appears today in the journal Nature Communications.

Glaciologists have long suspected that the ice sheet was unstable and could be sliding into the ocean, said David Bromwich, professor of geography and leader of the Ohio State team.

Until now, research has shown that the dominant cause was the melting from the warming of the ocean at the bottom of the ice shelf.

This research raises the possibility that the melting from below by the ocean water, as well as from the top by the atmosphere, could both be crucial factors to the melting of the ice sheet.

“If both of those happen simultaneously, it likely would significantly accelerate the rate at which that ice sheet is melting off into the ocean and raising sea levels,” Bromwich said.

Researchers found that despite strong westerly winds, the effects of last year’s El Nino were a dominating combative force that initiated the melting event.

“There is this competition between these two opposite influences: the El Ninos tend to bring warm air into West Antarctica and melt the snow and ice, and the stronger westerly winds tend to keep the warm ocean air offshore,” he said.

Bromwich said he expects the warming climate to produce only stronger, more frequent El Ninos in the future.

“Even if the westerly winds remain strong as they are, it’s very likely that we will see many more of these big melting events,” he said.

[COLIN JENKINSON/AUSTRALIAN BUREAU OF METEOROLOGY] Researchers have linked the accelerated melting of the Ross ice shelf in Antarctica to warm winds caused by the El Nino weather pattern.