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Climate: More snow in Antarctica will speed up ice loss

Antarctica ice-loss rate about equal to Greenland’s

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Increasing snowfall in Antarctica could — almost paradoxically — speed up the loss of ice mass. Bob Berwyn photo.

By Summit Voice

FRISCO — German researchers say they’ve placed another piece of the Antarctic climate puzzle by calculating how heavier snowfall on the frozen continent is likely to increase future ice discharges from the continental ice sheets.

Their study, published this week in Nature, shows that a lot of the Antarctic ice gain due to increased snowfall is countered by an acceleration of ice-flow to the ocean. Thus, Antarctica’s contribution to global sea-level rise is probably greater than estimated, the team of authors from the Potsdam Institute for Climate Impact Research concluded.

The research team’s ensemble of ice-physics simulations shows that future ice discharge will increased up to three times because of additional precipitation in Antarctica under global warming. During the last decade, the Antarctic ice-sheet has lost volume at a rate comparable to that of Greenland.

“Between 30 and 65 percent of the ice gain due to enhanced snowfall in Antarctica is countervailed by enhanced ice loss along the coastline,” said lead-author Ricarda Winkelmann. “The effect exceeds that of surface warming as well as that of basal ice-shelf melting,” Winkelmann added.

“The one certainty we have about Antarctica under global warming is that snowfall will increase,” Winkelmann explained. “Since surface melt might remain comparably small even under strong global warming, because Antarctica will still be a pretty chilly place, the big question is, how much more mass within the ice sheet will slowly but inexorably flow off Antarctica and contribute to sea-level rise, which is one of the major impacts of climate change.”

Since snowfall on the ice masses of Antarctica takes water out of the global water cycle, models suggest the continent’s net contribution to sea-level rise could be negative during the next 100 years.

The new findings indicate that this effect to a large extent is offset by changes in the ice-flow dynamics. Snow piling up on the ice is heavy and hence exerts pressure — the higher the ice the more pressure. Because additional snowfall elevates the grounded ice-sheet but less so the floating ice shelves, it flows more rapidly towards the coast of Antarctica where it eventually breaks off into icebergs and elevates sea level.

A number of processes are relevant for ice-loss in Antarctica, most notably to sub-shelf melting caused by warming of the surrounding ocean water. These phenomena explain the already observed contribution to sea-level rise.

“We now know that snowfall in Antarctica will not save us from sea-level rise,” said co-author Anders Levermann, research domain co-chair at PIK and a lead author of the sea-level change chapter of the upcoming IPCC’s 5th assessment report. “Sea level is rising – that is a fact. Now we need to understand how quickly we have to adapt our coastal infrastructure; and that depends on how much CO2 we keep emitting into the atmosphere,” Levermann concluded.

FRISCO — German researchers say they’ve placed another piece of the Antarctic climate puzzle by calculating how heavier snowfall on the frozen continent are likely to increase future ice discharges from the continental ice sheets.

Their study, published this week in Nature, shows that a lot of the Antarctic ice gain due to increased snowfall is countered by an acceleration of ice-flow to the ocean. Thus, Antarctica’s contribution to global sea-level rise is probably greater than estimated, the team of authors from the Potsdam Institute for Climate Impact Research concluded.

The research team’s ensemble of ice-physics simulations shows that future ice discharge will increased up to three times because of additional precipitation in Antarctica under global warming. During the last decade, the Antarctic ice-sheet has lost volume at a rate comparable to that of Greenland.

“Between 30 and 65 percent of the ice gain due to enhanced snowfall in Antarctica is countervailed by enhanced ice loss along the coastline,” said lead-author Ricarda Winkelmann. “The effect exceeds that of surface warming as well as that of basal ice-shelf melting,” Winkelmann added.

“The one certainty we have about Antarctica under global warming is that snowfall will increase,” Winkelmann explained. “Since surface melt might remain comparably small even under strong global warming, because Antarctica will still be a pretty chilly place, the big question is, how much more mass within the ice sheet will slowly but inexorably flow off Antarctica and contribute to sea-level rise, which is one of the major impacts of climate change.”

Since snowfall on the ice masses of Antarctica takes water out of the global water cycle, models suggest the continent’s net contribution to sea-level rise could be negative during the next 100 years.

The new findings indicate that this effect to a large extent is offset by changes in the ice-flow dynamics. Snow piling up on the ice is heavy and hence exerts pressure — the higher the ice the more pressure. Because additional snowfall elevates the grounded ice-sheet but less so the floating ice shelves, it flows more rapidly towards the coast of Antarctica where it eventually breaks off into icebergs and elevates sea level.

A number of processes are relevant for ice-loss in Antarctica, most notably to sub-shelf melting caused by warming of the surrounding ocean water. These phenomena explain the already observed contribution to sea-level rise.

“We now know that snowfall in Antarctica will not save us from sea-level rise,” said co-author Anders Levermann, research domain co-chair at PIK and a lead author of the sea-level change chapter of the upcoming IPCC’s 5th assessment report. “Sea level is rising – that is a fact. Now we need to understand how quickly we have to adapt our coastal infrastructure; and that depends on how much CO2 we keep emitting into the atmosphere,” Levermann concluded.

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2 Responses

  1. More snow causes more global warming, and less snow causes more global warming. Yea whatever.

    No wonder climate deniers look at alarmist like they are a bunch of confused air heads.

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