5. Why did temperature decrease from 1940-1970, while carbon increased steadily? The answer: “In the real world, there is both internal variability and other factors that affect climate (i.e. other than CO2). Some of those other forcings (sulphate and nitrate aerosols, land use changes, solar irradiance, volcanic aerosols, for instance) can cause cooling ” (realclimate.org) I have to agree. There are other real world factors that affect climate .