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Geoengineered methods can't fully offset human-caused climate change


January 26, 2012 - Washington

Injecting sulfate particles directly into the stratosphere to reduce the rate of future global warming would likely achieve only part of the desired effect, and could carry serious, if unintended, consequences, a new study has found.

The lower atmosphere already contains tiny sulfate and sea salt particles, called aerosols that reflect energy from the sun into space.

However, a new University of Washington modelling study shows that sulfate particles in the stratosphere will not necessarily offset all the effects of future increases in atmospheric carbon dioxide.

Kelly McCusker, lead author of the study, said that there still is likely to be significant warming in regions where climate change impacts originally prompted a desire for geoengineered solutions.

The modelling study shows that significant changes would still occur because even increased aerosol levels cannot balance changes in atmospheric and oceanic circulation brought on by higher levels of atmospheric carbon dioxide.

"There is no way to keep the climate the way it is now. Later this century, you would not be able to recreate present-day Earth just by adding sulfate aerosols to the atmosphere," McCusker said.

Using the National Center for Atmospheric Research's Community Climate System Model version 3 and working at the Texas Advanced Computing Center, the researchers found that there would, in fact, be less overall warming with a combination of increased atmospheric aerosols and increased carbon dioxide than there would be with just increased carbon dioxide.

They also found that injecting sulfate particles into the atmosphere might even suppress temperature increases in the tropics enough to prevent serious food shortages and limit negative impacts on tropical organisms in the coming decades.

But temperature changes in Polar Regions could still be significant. Increased winter surface temperatures in northern Eurasia could have serious ramifications for Arctic marine mammals not equipped to adapt quickly to climate change.

In Antarctic winters, changes in surface winds would also bring changes in ocean circulation with potentially significant consequences for ice sheets in West Antarctica.

The researchers concluded that even with geoengineering, there still could be climate emergencies like melting ice sheets or loss of polar bear habitat in the polar regions.

They added that the odds of a "climate surprise" would be high because the uncertainties about the effects of geoengineering would be added to existing uncertainties about climate change.

The study has been published online in the Journal of Climate.

ANI

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