What is causing the variability in global mean land temperature?

Diagnosis of climate models reveals that most of the observed variability of global mean land temperature during 1880-2007 is caused by variations in global sea surface temperatures (SSTs). Further, most of the variability in global SSTs have themselves resulted from external radiative forcing due to greenhouse gas, aerosol, solar and volcanic variations, especially on multidecadal time scales. Our results indicate that natural variations internal to the Earth's climate system have had a relatively small impact on the low frequency variations in global mean land temperature. It is therefore extremely unlikely that the recent trajectory of terrestrial warming can be overwhelmed (and become colder than normal) as a consequence of natural variability.