How a Stable Greenhouse Effect on Earth Is Maintained Under Global Warming Journal of Geophysical Research: Atmospheres

In a warming climate, greenhouse gases modulate thermal cooling to space from the surface and atmosphere, which is a fundamental feedback process that affects climate sensitivity. Recent studies have found that when relative humidity (RH) is constant with global warming, Earth's clear-sky longwave feedback would be dominated by surface cooling to space. Using a millennium-length coupled general circulation model and accurate line-by-line radiative transfer calculations, here we show that the atmospheric cooling to space accounts for 12%–50% of the feedback parameter from poles to tropics. A simple yet comprehensive model is proposed here for explaining the atmospheric feedback process. It is found that when RH is held constant,