摘要：GeologyisthescienceofhowtheEarthfunctionsandhasevolvedand,as such, it can contribute to our understanding of the climate systemand how it responds to the addition of carbon dioxide (CO 2 ) to theatmosphereandoceans.Observationsfromthegeologicalrecordshowthat atmospheric CO 2 concentrations are now at their highest levels inat least the past 3 million years. Furthermore, the current speed ofhuman-inducedCO 2 changeandwarmingis nearlywithoutprecedentin the entire geological record, with the only known exception beingthe instantaneous, meteorite-induced event that caused the extinctionof non-bird-like dinosaurs 66 million years ago. In short, whilstatmospheric CO 2 concentrations have varied dramatically during thegeological past due to natural processes, and have often been higherthan today, the current rate of CO 2 (and therefore temperature) changeis unprecedented in almost the entire geological past.
