Leaked Global Warming Report Cites Humans as Cause

In a copy of the fifth Assessment Report by the Intergovernmental Panel on Climate Change (IPCC) obtained by Reuters, scientists upped the likelihood that human activities are causing global warming to 95%. The United Nations report was due to be officially released sometime in September 2013.

The 95% figure is an increase over the 90% arrived at in the 2007 report, 66% in 2001, and the approximately 50% conclusion made in 1995. The remaining possibility in each case is that natural variability within the climate is the primary culprit behind rising temperatures, as opposed to human burning of fossil fuels leading to an increased greenhouse effect.

Along with the near certainty that humans are the cause of observed warming, according to the leaked report, comes uncertainty about the precise impacts warming will have throughout the globe in the coming years. Reuters notes that this uncertainty is problematic, as governments heavily rely on these reports to guide investments in renewable energy and climate change mitigation strategies, such as improving sea defenses in coastal regions.

This year’s study will make a stronger claim than in 2007 that manmade greenhouse gas emissions have caused more heat waves. It will, by contrast, limit previous claims that human activities have led to more droughts. Though many governments have agreed in principle to attempt to limit global warming to less than two degrees Celsius, the report will cite a high risk that global temperatures will rise higher than two degrees by the end of this century. The report will also state that evidence of rising sea levels has become “unequivocal.”

Despite these certainties, the report will provide little in the way of determining local impacts of climate change. It will also try to explain the much-discussed phenomenon of a possible slowdown in global warming. Though temperatures are still increasing, they have done so at a slower rate since 1998 than in years prior, even as greenhouse gas emissions climb higher. Scientists say reasons for this slowdown may include more volcanic ash dimming sunlight than expected, a decline in heat from the sun during the latest 11-year solar cycle, more heat being absorbed by the oceans and the possibility that the climate is less reactive to carbon dioxide build-up than expected.

The draft gives a projected range for sea level rise of 11.4 to 32.3 inches by the late 21st century, higher than the last report, which did not account for changes in Antarctica and Greenland properly.

Published in WholeFoods Magazine, October 2013