Greenhouse gas forcing and climate feedback signatures identified in hyperspectral infrared satellite observations

A satellite flies over the ocean surface. Credit: NOAA

Greenhouse gas emissions from human activities trap heat (radiative forcing) and cause global warming. This warming is amplified or diminished by feedbacks in the climate system. We had limited direct observations of global greenhouse gas forcing and feedbacks, despite the fact that they are the primary causes of climate change. While it has long been known that resolving the thermal spectrum at different wavelengths can help us to better separate the signals due to forcings and feedbacks,  observing  this has been elusive because of irregular, uncalibrated, or limited measurements. However, the Atmospheric Infrared Sounder (AIRS) instrument on NASA’s Aqua Satellite has recently provided such data (2003-2021).

To demonstrate that the forcing and feedback signals appearing in the AIRS thermal spectra (Figure 1a)  are consistent with the predictions of state-of-the-art climate models and reanalysis data, the authors conducted novel climate change simulations with several of GFDL’s models (AM3, AM4, CM3, and a radiation model, GFDL-GRTCODE) at each thermal wavelength, month, and location across the globe during 2003-2021.