Towards Reassessing the Cryosphere Contribution to Earth’s Energy Imbalance

The Earth’s Energy Imbalance (EEI) provides a measure of net energy accumulation in the climate system driven by human emissions. The cryosphere plays an important role by absorbing energy primarily through phase change associated with the melt of glaciers, ice sheets, and sea ice. Land-based ice melt is, together with thermal expansion, the major contributor to global mean sea level rise. Recent Earth Heat Inventory estimates suggest that the cryosphere contributed to approximately 4% of total heat uptake over the period 1960-2020, mostly via latent heat of fusion required to convert ice to water.

However, the total heat uptake from the cryosphere term remains uncertain due to heterogeneous data coverage, methodological inconsistencies, and incomplete accounting of some cryospheric processes. In particular, observational constraints differ strongly between glaciers, ice sheets, and sea ice, and not all relevant energy pathways have been consistently quantified in previous efforts. These current limitations hamper robust annual updates needed for operational climate indicator efforts such as the Indicators of Global Climate Change and will likely become increasingly relevant for future assessments (e.g., for upcoming IPCC AR7).

Here, we outline a framework to update the cryospheric heat uptake by compiling and harmonizing the latest observational datasets on cryosphere change, converting mass and volume losses into energetic equivalents, and assessing uncertainty propagation and methodological sensitivity. Additionally, we also explore how cryosphere heat uptake may change in the future. As such, this work aims to refine the cryospheric contribution to the EEI, clarify its temporal evolution, and improve consistency between observational and model-based global energy budget estimates.