Professor Rob Raiswell, a geologist at the University of Leeds, says 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 believes that the accumulated frozen mud could breathe life into the icy waters around Antarctica, triggering a large, natural removal of carbon dioxide from the atmosphere.
And as rising temperatures cause the ice sheets to break up faster, creating more icebergs, the amount of carbon dioxide removed will also rise. Raiswell says:' It won't solve the problem, but it might buy us some time.'
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.
A key question is how much of the carbon soaked up by the growing plankton is returned to the atmosphere. 'We simply don't know the answer to that,' Raiswell said. 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. David Vaughan, a glaciologist with the British Antarctic Survey, said: 'It's a very interesting new line of research and one that should be looked at in more detail.'
No comments:
Post a Comment