The hockey-stick curve

There has been a rapid increase of co₂ concentrations in the atmosphere over the past 250 years: from 280 parts per million (ppm) to 379 ppm. All greenhouse gases add up to the equivalent of 430 ppm of co₂. That this increase has had a warming effect because of heat energy trapped in the atmosphere is clear when one compares the well known hockey-stick graph of emissions with corresponding global temperature change.

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