claim: The final amount of extra CO2 that remains in the atmosphere stays there on a time scale of centuries.
evidence: Atmospheric CO2 has risen over the last 150 years to current levels of over 390 ppmv, from the 180 – 300 ppmv of the prior 800 thousand years This rise in temperature has reduced the Arctic ice cap to 1,100,000 sq mi ( 2,800,000 km2 ),[ citation needed ] smaller than ever recorded.