The Importance of CO2 in Climate Change

As temperature rises, air can hold more water vapor, and this together with temperature, pressure and winds can lead to more clouds. Hence an increase in CO2 can produce more water vapor and clouds , amplifying the effect. The GISS numerical climate model calculates that when CO2 is doubled, the feedbacks produce five times the greenhouse effect from CO2 alone. Observations confirm this relationship.

For the global cooling aficionados: Because of this non-linear impact of CO2 on absorption, the effect of removing the CO2 is about seven times as large as doubling it.