It might make a lot more sense to draw a correlation between man-made carbon dioxide levels and rising temperatures if the temperatures hadn’t decreased in the last decade.
Studies show that average global temperatures have decreased as much as 0.2 degrees Celsius over the last ten years — just as human activity is thought to be taking its biggest toll on the planet’s climate.
The decrease is small, to be sure, but, say skeptics, it disproves the argument that rising man-made CO2 levels are the driving force behind global warming.
“The Earth’s climate has always alternated between warming and cooling phases,” said William Happer, who served the Department of Energy under former President George H.W. Bush. “In the medievel warming period, when the Norse settled Greenland, the Earth warmed as fast or faster than it has since 1800. ... What should world governments have done in the year 900 A.D., when people noticed that the climate was warming and the ice was melting in southern Greenland?”