The Atmosphere’s Substantial Role in Interannual Variability of Earth’s Energy Imbalance

Earth’s Energy Imbalance (EEI) is a key metric to quantify climate change. In the long-term mean, most of this excess heat is absorbed by the ocean due to its large thermal capacity.  A comparatively small fraction warms the land, melts ice and warms and moistens the atmosphere. However, this contribution shows that atmospheric storage plays a non-trivial role on shorter timescales.  We investigate the balance among variations in the global flux at the top of the atmosphere (TOA), the rate of oceanic warming, and storage variations in atmosphere, land, and sea ice from year to year over 2005-2024. We find that changes in ocean warming lead the net energy flux at TOA by 2 months, and these two time-series are fairly well correlated on these interannual time scales, but the sum of atmospheric and oceanic rates of energy uptake are better correlated with a maximum correspondence at zero time lag. Further improvements of the correlation are modest when also including energy storage variations in land and sea ice. Hence the atmosphere generally plays an important role in buffering and redistributing year-to-year energy uptake by the climate system, most notably during El Niño and La Niña events. Atmospheric heat uptake played a particularly strong role in 2023, when surface temperatures increased remarkably and the global net TOA flux reach a new record high, but ocean heat uptake showed a less extreme anomaly. These results demonstrate the need to monitor energy storage variations in all compartments of the climate system to better understand variations in EEI.