[Azred]

Consensus proves nothing except that lots of people, scientists included, want to take graphs of data (some of which may not go back terribly far, perhaps 50 or 100 years) and then use a linear extrapolation to show where things "will" be in another 20 or 30 years.

As a counter to the above link, check out some of the information and graphs from Climate Skeptic. Amongs its gems are charts showing the following:

glaciers have been shrinking (compared to base year 1950) since 1750

sea levels have been rising since 1800

a discussion of the famous "hockey stick" graph, including the fact that some of the data lines are truncated--one in about 1950 (light blue, labelled BOS2001) and another in 1961 (dark green, for tree ring data); not coincidentally, both data lines show downward trends in later years

a comparison graph that shows two similar warming trends, one from 1957-2008 and another from 1895-1946

charts showing sunspot activity, which was unusually quiet from 1880-1940 and then active since then, with peaks around 1960 and 1990

charts showing the correlation of the Pacific Decadal Oscillation and average global temperatures (when the ocean warms up, we all warm up; when it cools down, we all cool down)

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It is a known fact that the Earth warms up and cools down; this is nature at its cyclic finest. However, we human beings are simply NOT disrupting this cycle by any significant amount.