‘Block the sun, control global warming’

Canadian and US scientists want to block the sun to cool the earth and limit global warming.

Research and field-testing on what they call “geo-engineering” of the earth’s atmosphere to limit risk of climate change must begin quickly, say scientists from the University of Calgary in Canada, and the University of Michigan and Carnegie Mellon University in the US.

Studies on geo-engineering or solar radiation management (SRM) should be undertaken collectively with government funding, rather that unilaterally by nations, argue the scientists.

They say SRM would involve releasing mega-tonnes of light-scattering aerosol particles in the upper atmosphere to reduce earth’s absorption of solar energy, thereby cooling the planet.

Another technique would be to release particles of sea salt to make low-altitude clouds reflect more solar energy back into space, the scientists say.

“Collaborative and government-supported studies on solar-radiation management will help identify technologies to combat climate change,” writes David Keith of Calgary university in an article in Nature this week.

“Solar-radiation management may be the only human response that can fend off rapid and high-consequence climate change impacts. The risks of not doing research outweigh the risks of doing it,” says Keith, who has co-authored the opinion piece with Edward Parson at the University of Michigan and Granger Morgan at Carnegie Mellon University.

However, SRM should not take the place of deep cuts in industrial greenhouse gas emissions and taking action to adapt to climate change, say the scientists.

They say: “We must develop the capability to do SRM in a manner that complements such cuts, while managing the associated environmental and political risks.”

The scientists want governments worldwide to establish a global research budget for SRM. This budget should grow about $10 million to $1 billion a year between now and 2020, they say.

They say research results should be made available to every nation and risk assessments be as transparent and international as possible.

Last decade warmest on record, says NASA

The last decade from January 2000 to December 2009 was the warmest on record, according to a NASA analysis.

Looking back to 1880, when modern scientific instrumentation became available to monitor temperatures precisely, a clear warming trend is present, although there was a levelling off between the 1940s and 1970s.

The past year happened to be the second warmest year on record, just a tiny fraction of a degree cooler than 2005. This puts 2009 in a virtual tie with a cluster of other years — 1998, 2002, 2003, 2006, and 2007 — for the second warmest slot on record.

Although 2008 was the coolest year of the decade because of a strong La Nina — an ocean-atmosphere phenomenon — that cooled the tropical Pacific Ocean, 2009 saw a return to near-record global temperatures as La Nina diminished, said a NASA release.

The results were based on a new analysis by NASA’s Goddard Institute for Space Studies (GISS) in New York.

In the past three decades, the GISS surface temperature record shows an upward trend of about 0.2 degrees Celsius per decade. In total, average global temperatures have increased by about 0.8 degrees Celsius since 1880.