<h4>Purpose of review</h4>The purpose of this review is to summarise the recent literature and scientific challenges on the topic of reconciling estimates of ocean heating rates with satellite-based monitoring of Earth's radiation budget (ERB), including discussion of the satellite record and in situ ocean observing system.<h4>Recent findings</h4>State-of-the-art climate model simulations suggest that the global ocean becomes the dominant term the planetary heat budget on annual and longer timescales. Therefore, we expect to see a close correspondence between year-to-year variations in ocean heating rates and satellite measurements of ERB. Recent comparisons of satellite ERB time series and ocean heating rates show a marked improvement over earlier studies in terms of consistency and specification of uncertainties. Contemporary research has also emphasised the utility of these independent data sets for cross validation of the climate record and their fundamental importance for monitoring the rate of climate change.<h4>Summary</h4>Anthropogenic greenhouse gas emissions have brought about an imbalance in Earth's radiation budget that is driving global climate change. Our primary means for monitoring this energy imbalance is via direct satellite measurements of ERB and through estimates of global ocean heat content (OHC) change. CERES satellite measurements of ERB offer high spatiotemporal resolution and uncertainties on annual time series of order 0.1 Wm^-2 but cannot provide absolute monitoring of Earth's energy imbalance due to limitations in sensor calibration. The Argo array of autonomous profiling floats has revolutionised the ocean observing system and our ability to estimate absolute ocean heating rates with current uncertainties estimated to be 0.5/0.1 Wm^-2 on annual/decadal timescales. These ocean observations are essential to "anchor" the time series of ERB and can be used to mitigate satellite sensor drifts. Sustaining these highly complementary elements of the climate observing system is essential for improved understanding of climate variability and change. Improvements in satellite sensor calibration, estimates of total solar irradiance and more comprehensive sampling of the global oceans (e.g. Deep Argo) are key aspects to reducing uncertainties in future observations of Earth's energy imbalance.

Abstract Table 2.1 compares the principal sources of energy available to drive the Earth’s climate system. It confirms what we would expect intuitively: that virtually all, in fact 99.97%, of the energy arrives from the Sun in the form of electromagnetic radiation. The remainder, from the interior of the Earth, from space in the form of energetic particles (most, but not all, of which also originate in the Sun), cosmic rays, and from human power production using fossil and radioactive fuels, are negligible for most purposes.

on incoming solar and outgoing infrared radiation, with major implications for the earth’s energy budget … for changes of solar radiation are solar flares. A considerable part of the solar radiation spectrum, essen- … upward flux of solar radiation above the smoke layer, Up, to the reflection of the incoming solar flux Dy and

changes of solar radiation are solar flares. A considerable part of the solar radiation spectrum … significant radiative impact on incoming solar and outgoing infrared radiation, with major implications … of solar radiation above the smoke layer, Uq, to the reflection of the incoming solar flux

incoming solar energy as a function of both height and latitude. Energy balance models, though, are fundamentally limited by their focus on radiation

Earth's energy budget (or Earth's energy balance) is the balance between the energy that Earth receives from the Sun and the energy the Earth loses back Earth's energy budget (or Earth's energy balance) is the balance between the energy that Earth receives from the Sun and the energy the Earth loses back into outer space. Smaller energy sources, such as Earth's internal heat, are taken into consideration, but make a tiny contribution compared to solar energy. The energy budget also takes into account how energy moves through the climate system. Th Aeros… In simplest terms, Earth's energy budget is balanced when the incoming flow equals the outgoing flow. Since a portion of incoming energy is directly reflected, the balance can also be stated as absorbed incoming solar (shortwave) radiation equal to outgoing longwave radiation: