Climate variability and relationships between top-of-atmosphere radiation and temperatures on Earth

Water vapor is positively correlated with tropospheric temperatures and thus also negatively correlated with net radiation; however, when the temperature dependency of water vapor is statistically removed, a significant positive feedback between water vapor and net radiation is revealed globally with 0.87 W m⁻² less OLR to space per millimeter of total column water vapor. The regression coefficient between global RT and tropospheric temperature becomes -2.98 W m⁻² K⁻¹ if water vapor effects are removed, slightly less than expected from blackbody radiation (-3.2 W m⁻² K⁻¹), suggesting a positive feedback from clouds and other processes.

Robust regional structures provide additional physical insights. The observational record is too short, weather noise too great, and forcing too small to make reliable estimates of climate sensitivity.