Can Melting Antarctic Ice Sheets Solve Global Warming?

by Hannah Punitha on Dec 8 2008 5:18 PM

Though melting Antarctic ice sheets have become potent symbols of global warming, they may actually turn out to help in the battle against climate change and soaring carbon emissions.

According to a report in the Guardian, Professor Rob Raiswell, a geologist at the University of Leeds, said that as the sheets break off the ice covering the continent, floating icebergs are produced that gouge minerals from the bedrock as they make their way to the sea.

Raiswell determined that the accumulated frozen mud could breathe life into the icy waters around Antarctica, triggering a large, natural removal of carbon dioxide (CO2) from the atmosphere.

As rising temperatures cause the ice sheets to break up faster, creating more icebergs, the amount of carbon dioxide removed will also rise.

"It won’t solve the problem, but it might buy us some time," Raiswell said.

As the icebergs drift northwards, they sprinkle the minerals through the ocean. Among these minerals, Raiswell’s research shows, are iron compounds that can fertilise large-scale growth of photosynthetic plankton, which take in carbon dioxide from the air as they flourish.

According to his calculations, melting Antarctic icebergs already deposit up to 120,000 tonnes of this ’bioavailable’ iron into the Southern Ocean each year, enough to grow sufficient plankton to remove some 2.6 billion tonnes of carbon dioxide, equivalent to the annual carbon pollution of India and Japan.

A 1 per cent increase in the number of icebergs in the Southern Ocean could remove an extra 26 million tonnes of CO2, equivalent to the annual emissions of Croatia.

"We see the rapid ice loss in Antarctica as one obvious sign of climate warming, but could it be the Earth’s attempt to save us from global warming?" said Raiswell.

Raiswell and colleagues at the University of Bristol and the University of California describe how they chipped samples off four Antarctic icebergs blown ashore on Seymour island by a storm in the Weddell Sea.

They found that they contained grains of ferrihydrite and schwertmannite, two iron minerals that could boost plankton growth.

"These are the first measurements of potentially bioavailable iron on Antarctic ice-hosted sediments," they said.

"Identifying icebergs as a significant source of bioavailable iron may shed new light on how the oceans respond to atmospheric warming," they added.

Seeding the oceans with iron will only benefit the climate if the plankton sink to the bottom when they die, taking the carbon with them, according to the research.