Since 1978, solar irradiance has been measured by satellites.[105] These measurements indicate that the Sun's radiative output has not increased during that time, so the warming during the past 40 years cannot be attributed to an increase in solar energy reaching the Earth.

Climate models have been used to examine the role of the Sun in recent climate change.[106] Models are unable to reproduce the rapid warming observed in recent decades when they only take into account variations in solar output and volcanic activity. Models are, however, able to simulate the observed 20th century changes in temperature when they include all of the most important external forcings, including human influences and natural forcings.

Another line of evidence is differing temperature changes at different levels in the Earth's atmosphere.[107] Basic physical principles require that the greenhouse effect produces warming of the lower atmosphere (the troposphere) but cooling of the upper atmosphere (the stratosphere).[108][109] Depletion of the ozone layer by chemical refrigerants has also resulted in a strong cooling effect in the stratosphere. If solar variations were responsible for observed warming, warming of both the troposphere and stratosphere would be expected.[110]