Earth’s Global Energy Budget and Transport

The study of the global energy budget and the energy flow in the Earth system is essential for understanding current climate change. To understand how energy is accumulating and being distributed within the climate system, an observationally constrained reconstruction of energy fluxes at the top of atmosphere has been used to infer the surface energy fluxes from 1985-2018, and the mass-corrected atmospheric energy divergence from ERA5 has been further adjusted to match the observed mean land heat uptake. New satellite and ocean data are combined with an improved methodology to quantify recent variability in meridional and ocean to land heat transports since 1985. A global top of atmosphere net imbalance is found to increase from 0.10 ± 0.61 W m⁻² over 1985–1999 to 0.62 ± 0.1 Wm⁻² over 2000–2016, and the uncertainty of ± 0.61 Wm⁻² is related to the Argo ocean heat content changes (± 0.1 Wm⁻²) and an additional uncertainty applying prior to 2000 relating to homogeneity adjustments.

The northward oceanic heat transports are derived from the derived surface fluxes and estimates of ocean heat accumulation. The inferred cross-equatorial oceanic heat transport of 0.50 PW is higher than most previous studies, and the derived mean meridional transport of 1.23 PW at 26° N is very close to 1.22 PW from RAPID observation. The surface flux contribution dominates the magnitude of the oceanic transport, but the integrated ocean heat storage controls the interannual variability.

The inferred surface fluxes are compared with other commonly used flux products. On station-scale, a comprehensive comparison of inferred and buoy-based fluxes is presented. On regional scale, the oceanic energy fluxes in North Atlantic is evaluated against RAPID observations. Results indicate that global land and ocean averages of inferred surface fluxes agree with the observed heat uptake to within 1 W m⁻², while satellite-derived and model-based fluxes show large global mean biases.