Why is Earth’s Energy Imbalance Growing?
Anthropogenic greenhouse gas emissions are disrupting Earth’s radiative balance: The incoming visible solar radiation and the thermal radiation emitted into space are no longer in balance, causing energy to accumulate within the Earth system. As expected, this has led to the melting of ice and the warming of the atmosphere, ocean, and land masses. Over the 25 years since this imbalance has been reliably measured, it has grown at a rate that caught the scientific community by surprise. This has led some researchers to speculate that global warming is accelerating. To get to the bottom of this concerning trend and its implications, 44 researchers from Asia, across Europe, and north America met at Ringberg Castle on Lake Tegernsee in March 2026, at the invitation of the Max Planck Institute for Meteorology (MPI-M). A recently published report summarizes the workshop's key discussion points and findings and serves as a starting point for further investigation.
Analysis and interpretation of CERES data
The discussions revolve around data from the CERES project (Clouds and the Earth’s Radiant Energy System) of the U.S. space agency NASA. Since 1997, CERES has been using various satellites to measure radiant energy fluxes at the top of the atmosphere. The goal of the workshop was to verify the observed trend of increasing energy imbalance, identify possible causes, and develop approaches to further investigate the issue.
First, the researchers broke the problem down into its individual parts. They rigorously scrutinized all assumptions, considered different perspectives, and analyzed the details. Are the CERES data reliable, and is the measured strength of the trend consistent with the increased heat content of the ocean and atmosphere? What are the physical characteristics of the trend, and what clues do they provide regarding the causes? Is the theoretical framework sufficient for the analysis?
First results and further research needs
When it comes to the trend itself, the scientists concluded that the energy imbalance had increased by between 0.3 and 0.5 W/m² per decade between 2005 and 2024. This trend was particularly driven by the short-wave range of the electromagnetic spectrum. This means that the planet has darkened, mostly because of less ice near the poles and fewer clouds. Cloud reductions can arise from the warming itself, circulation changes, or changes in the aerosol burden, whereby the focus is often on the latter. To investigate these issues the researchers developed hypotheses that could be tested through complementary measurements from field campaigns or satellite missions. Furthermore, they propose process studies using climate models at the kilometer scale. Thanks to increased computing power, such simulations covering the entire period of CERES measurements have recently become possible.
The authors emphasize the importance of the CERES project and its continuation for climate research. They also point out that climate change assessments still lag in their use of the observational record, comprising measurements like those by CERES. In explaining the CERES data they stress that adequate answers must explain all aspects of the radiative balance, including the distinction between short-wave and long-wave components and between all-sky and clear-sky conditions and their regional distribution. Furthermore, further CERES developments to ensure the long-term continuity of the record and improved data diagnostics—such as improvements in cloud classification—could provide additional insights.
Original publication
Stevens, B. Et al. (2026) Earth’s net incoming energy-flux imbalance (and its implications for understanding climate change). Reports on Earth System Science No. 301, DOI: 10.17617/2.3711842