Earth's energy budget
Earth's energy budget (or Earth's energy balance) accounts for 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 accounts for how energy moves through the climate system.[2]: 2227 The Sun heats the equatorial tropics more than the polar regions. Therefore, the amount of solar irradiance received by a certain region is unevenly distributed. As the energy seeks equilibrium across the planet, it drives interactions in Earth's climate system, i.e., Earth's water, ice, atmosphere, rocky crust, and all living things.[2]: 2224 The result is Earth's climate.
This article is about energy flows at and above Earth's surface. For Earth's internal heat, see Earth's internal heat budget.
Earth's energy budget depends on many factors, such as atmospheric aerosols, greenhouse gases, surface albedo, clouds, and land use patterns. When the incoming and outgoing energy fluxes are in balance, Earth is in radiative equilibrium and the climate system will be relatively stable. Global warming occurs when earth receives more energy than it gives back to space, and global cooling takes place when the outgoing energy is greater.[3]
Multiple types of measurements and observations show a warming imbalance since at least year 1970.[4][5] The rate of heating from this human-caused event is without precedent.[6]: 54 The main origin of changes in the Earth's energy is from human-induced changes in the composition of the atmosphere.[1] During 2005 to 2019 the Earth's energy imbalance (EEI) averaged about 460 TW or globally 0.90 ± 0.15 W per m2.[1]
It takes time for any changes in the energy budget to result in any significant changes in the global surface temperature. This is due to the thermal inertia of the oceans, land and cryosphere.[7] Most climate models make accurate calculations of this inertia, energy flows and storage amounts.
