Adrian (R) and his son John Herbert walk past an overturned travel trailer in their neighborhood in Houma, Louisiana, which was heavily damaged as Hurricane Gustav passed through, September 1, 2008. REUTERS/Mark Wallheiser (UNITED STATES)We seem to hear more and more about natural weather disasters – are these signs of global warming? 

Or do they just illustrate the unpredictability of the weather?

Luckily, Hurricane Gustav doesn’t seem to have inflicted devastation on the U.S. Gulf coast comparable to Katrina in 2005. On the other side of the world, the worst floods in India’s Bihar province in 50 years have displaced about three million people and killed at least 90.

Achim Steiner, head of the U.N. Environment Programme, says that more powerful hurricanes and more floods are in line with predictions by the U.N. Climate Panel of ever more disruptions linked to a build-up of greenhouse gases.    Flood-affected people wait for a rescue team at Chondipur village of Madhepura district in India’s eastern state of Bihar August 31, 2008. Authorities struggling to provide aid after devastating floods in Bihar said on Sunday they needed more boats and rescuers to help hundreds of thousands of people still marooned in remote villages. REUTERS/Rupak De Chowdhuri (INDIA)

The panel said in a 2007 report that global warming was already “unequivocal” and that it was at least 90 percent likely that human activities — led by burning fossil fuels — were the main cause of warming in the past 50 years.

It said observed shifts include “changes in arctic temperatures and ice, widespread changes in precipitation amounts, ocean salinity, wind patterns and aspects of extreme weather including droughts, heavy precipitation, heatwaves and the intensity of tropical cyclones.”