Friends of Science list 10 reasons disproving the myths of man-made global warming. I can not improve on their list so here it is in its entirety:
COMMON MISCONCEPTIONS ABOUT GLOBAL WARMING
MYTH 1: Global temperatures are rising at a rapid, unprecedented rate.
FACT: The HadCRUT3 surface temperature index shows warming to 1878, cooling to 1911, warming to 1941, cooling to 1964, warming to 1998 and cooling through 2011. The warming rate from 1964 to 1998 was the same as the previous warming from 1911 to 1941. Satellites, weather balloons and ground stations all show cooling since 2001. The mild warming of 0.6 to 0.8 C over the 20th century is well within the natural variations recorded in the last millennium. The ground station network suffers from an uneven distribution across the globe; the stations are preferentially located in growing urban and industrial areas (“heat islands”), which show substantially higher readings than adjacent rural areas (“land use effects”). Two science teams have shown that correcting the surface temperature record for the effects of urban development would reduce the warming trend over land from 1980 by half.
There has been no catastrophic warming recorded.
MYTH 2: The “hockey stick” graph proves that the earth has experienced a steady, very gradual temperature decrease for 1000 years, then recently began a sudden increase.
FACT: Significant changes in climate have continually occurred throughout geologic time. For instance, the Medieval Warm Period, from around 1000 to1200 AD (when the Vikings farmed on Greenland) was followed by a period known as the Little Ice Age. Since the end of the 17th Century the “average global temperature” has been rising at the low steady rate mentioned above; although from 1940 – 1970 temperatures actually dropped, leading to a Global Cooling scare.
The “hockey stick”, a poster boy of both the UN’s IPCC and Canada’s Environment Department, ignores historical recorded climatic swings, and has now also been proven to be flawed and statistically unreliable as well. It is a computer construct and a faulty one at that.
Climate Change Sanity 