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Now that ClimateGate has buried the fraudulent hockey stick for good, it is easy to prove that global warming is not man-made: just compare the timing of our carbon dioxide emissions with the timing of global warming.

Human Emissions of Carbon Dioxide

Emissions of carbon dioxide by humans are easy to estimate from our consumption of coal, oil, and natural gas, and production of cement:



The vast bulk of human emissions occurred after 1945, during post-WWII industrialization. Half of all human consumption of fossil fuels and cement production has occurred since the mid 1970s.

Temperatures

Global temperature proxies (sediments, boreholes, pollen, oxygen-18, stalagmites, magnesium to calcium ratios, algae, cave formation, etc. over a wide geographical range) show a warming trend starting around 1700, with warming and cooling periods about the trend:



Compare the Timing

The timing is all wrong for the theory of manmade global warming:

Temperature increases started in 1700, and the underlying rate of increase has been roughly steady (though there have been warming and cooling fluctuations around the trend).

Human emissions of carbon dioxide were negligible before 1850, and really only took off after 1945.

If human emissions of carbon dioxide caused global warming, then there would be massive and accelerating global warming after 1945 and almost no global warming before 1945. Obviously this is not the case.

Conclusions

There is almost no relationship between human emissions and global temperature, so global warming is not mainly due to human emissions of carbon dioxide.

Something other than human emissions caused the global warming prior to 1850.

The steadiness of the underlying temperature trend since 1700 suggests that whatever caused the warming prior to 1850 is still causing warming, and that the effect of human emissions of carbon dioxide is relatively insignificant.