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Thursday, August 26, 2010



‘Sea levels may rise up to 70 cm by 2100’

150 M May Be Affected If Sea Levels Rise By 30-70 Cm

London: Ocean levels could significantly rise up to 70 cm by 2100 due to climate change and even the most extreme geoengineering approaches would not be able to stop sea levels from rising, according to a new study.
    The study published in the journal ‘Proceedings of the National Academy of Sciences’ (PNAS) proposes that as many as 150 million people could be affected as ocean levels could rise by 30 cm to 70 cm.
    Scientists led by John Moore from Beijing Normal University, China, said that to combat global warming, people need to concentrate on sharply curbing greenhouse gas emissions and not rely too much on proposed geoengineering methods. 

    "Substituting geoengineering for greenhouse emission control would be to burden future generations with enormous risk," said Svetlana Jevrejeva of the UK's National Oceanography Centre, a coauthor of the study.
    Jevrejeva and colleagues from China, Finland and Denmark wanted to see how five geoengineering solutions will affect sea levels.
    Geoengineering falls into two main types: limiting the 
effect of the sun's rays, or changing the carbon cycle in some way. The former doesn't change atmospheric CO2 levels in any way, whereas the latter does.
    The team used a well-established model to look at the effect of firing a large amount of sulphur dioxide into the atmosphere, putting mirrors in space, planting huge numbers of trees, biochar (turning plants into a type of charcoal in soil where they boost crop productivity) and switching to bio-energy.
    They investigated how these methods would affect climate change under different CO2 emissions scenarios. 

    They found that using bioenergy for power while capturing the emitted CO2 and storing it deep underground is likely to be the least risky and the most publicly acceptable solution to tackle climate change. This would also lead to fewer fossil fuels being burnt for energy. But this solution wouldn't be as effective as using aerosols or giant mirrors in space at slowing sea level rise.
    Firing as much sulphur dioxide into the atmosphere as the eruption of Mount Pinatubo did, every 18 months, could slow sea level rise by 40 to 80 years, they discovered. But the effects of pumping so much sulphur dioxide into the sky are unknown. 

    "We don't know how aerosols will affect ecosystems and the climate," says Jevrejeva. "But they're likely to disrupt rainfall patterns and stratospheric ozone." Erecting mirrors in space to reflect the sun's rays, on the other hand, is a nice, clean idea and could limit sea level rise, but it would be prohibitively expensive. This isn't only because of the costs of getting the mirrors into space, but also because of the maintenance required to keep them going. PTI

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