Trends and variations in heat uptake of the Arctic climate system

A recent assessment of the coupled atmosphere-ocean-sea-ice energy budget of the Arctic using largely independent observational data sources demonstrated a high level of consistency of yearly means and annual cycles of lateral and vertical energy fluxes and storage terms. Moreover, contemporary Arctic regional energy imbalance has been found to be of similar magnitude (~1Wm^-2) as Earth’s global energy imbalance. This suggests that Arctic amplification is predominantly a surface phenomenon and its imprint on the vertically integrated energy budget is small. Nevertheless, the annual cycle of the observed Arctic energy budget has amplified over the past two decades, with marked changes in seasonal patterns of energy fluxes and storage. This contribution draws on satellite observations, mooring-derived oceanic fluxes, data from the fifth European Re-Analysis (ERA5), and state-of-the-art ocean reanalyses to examine recent changes in Arctic heat accumulation as well as trends and variability in seasonal energy budgets. Implications for seasonal energy transports from mid-latitudes towards the Arctic will be discussed as well.