Global Warming Trends 1919-2005
A WSJ article by global warming skeptic Richard Lindzen has some useful stylized facts.
Most of the climate community has agreed since 1988 that global mean temperatures have increased on the order of one degree Fahrenheit over the past century, having risen significantly from about 1919 to 1940, decreased between 1940 and the early ’70s, increased again until the ’90s, and remaining essentially flat since 1998.
There is also little disagreement that levels of carbon dioxide in the atmosphere have risen from about 280 parts per million by volume in the 19th century to about 387 ppmv today. Finally, there has been no question whatever that carbon dioxide is an infrared absorber (i.e., a greenhouse gas–albeit a minor one), and its increase should theoretically contribute to warming. Indeed, if all else were kept equal, the increase in carbon dioxide should have led to somewhat more warming than has been observed, assuming that the small observed increase was in fact due to increasing carbon dioxide rather than a natural fluctuation in the climate system.