NASA's Dr James Hansen says that an atmospheric CO2 concentration of about 325 needed to restore planetary energy balance and about 300 ppm CO2 is needed to restore Arctic sea ice to what it was 25 years ago.
Dr. James Hansen, the Director of the NASA Goddard Institute for Space Studies and a world renowned expert on global warming, gave the keynote address at the May 2, 2009:
"To restore the planetary energy balance carbon dioxide levels should be at 325 ppm. To restore arctic sea ice to its coverage area of 25 years ago, carbon dioxide levels closer to 300 ppm would be needed."
For the opinions of other top climate scientists on the the need to reduce atmospheric CO2 concentration to about 2300 ppm see 300.org: 300.org - return atmosphere CO2 to 300 ppm .
Post #1 should obviously read " opinions of other top climate scientists on the the need to reduce atmospheric CO2 concentration to about 300 ppm".
Key quote:
"He [Dr Hansen] said current focus on stabilizing carbon dioxide concentrations at 450 to 500 ppm are misguided and the safe not-to-exceed threshold is 350 ppm."
You're in Easy Mode. If you prefer, you can use XHTML Mode instead. |