Plan to reverse global warming could backfire

By Julie Steenhuysen

CHICAGO (Reuters) - A proposed solution to reverse the effects of global warming by spraying sulfate particles into Earth's stratosphere could make matters much worse, climate researchers said on Thursday.

They said trying to cool off the planet by creating a kind of artificial sun block would delay the recovery of the Antarctic ozone hole by 30 to 70 years and create a new loss of Earth's protective ozone layer over the Arctic.

"What our study shows is if you actually put a lot of sulfur into the atmosphere we get a larger ozone depletion than we had before," said Simone Tilmes of the National Center for Atmospheric Research in Boulder, Colorado, whose research appears in the journal Science.

The sulfur injection idea has been proposed by a number of climate scientists as a potential solution to global warming.

Tilmes said the idea was intended to mimic the effects of a major volcanic eruption. Such eruptions in the past sent plumes of sun-blocking sulfur into an upper layer of the atmosphere known as the stratosphere that cooled temperatures on Earth.

Ozone in the stratosphere provides a protective layer high above Earth's surface that guards against harmful solar radiation.

Antarctica's ozone layer has been steadily thinning, resulting in a seasonal "hole" above the South Pole.

"We know that particles would result in the cooling of the planet," Tilmes said in a telephone interview.