James Hansen, one of the world’s most eminent climate scientists and director of NASA’S Goddard Institute for Space Studies in New York City, is nearly certain that the concentration of carbon dioxide (CO2) in the atmosphere has already risen beyond safe levels. The atmospheric concentration of CO2 remained between 260 and 280 parts per million for approximately 10,000 years until about 1750, the start of the industrial era. Since then, it is widely acknowledged that human activity has increased the concentration of CO2 and other greenhouse gases (GHG). The current concentration is 385 parts per million and is rising by 2 ppm per year. Hansen claims that the goal to keep global warming less than two degrees Celsius and GHG concentration at 450 ppm or lower (for which GHG emissions must peak by 2015) is “a recipe for global disaster, not salvation.” He and others are now calling for a level of no more than 350 ppm. This June 2008 article by Hansen came 20 years after his 1998 testimony to Congress, which sounded one of the first alarm bells on the dangers of global warming.
To read “Global Warming Twenty Years Later: Tipping Points Near,” click here: