CO2's paradox: surface warming, stratospheric cooling explained

A Nature Geoscience study shows rising CO2 makes the stratosphere more efficient at radiating infrared heat into space, causing cooling of the upper atmosphere (about 2°C since the mid-1980s), with faster cooling higher up near the stratopause. Researchers describe a 'Goldilocks zone' of infrared wavelengths that drive this cooling, while ozone and water vapor play smaller roles. If CO2 doubles, stratospheric temperatures near the stratopause may drop roughly 8°C, highlighting a key, quantifiable climate fingerprint and its implications for Earth's energy balance and exoplanet atmospheres.