Now, let’s consider the connection between this idea of an energy flow system to the actual Earth. As shown in the figure below, this system includes the atmosphere, the oceans, volcanoes, plants, ice, mountains, and even people — it is intimately connected to the whole planet. We will get to some of these other components of the climate system later, but to begin with, we will focus on just the energy flows — the yellow and red arrows shown below.
Global Climate System
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Basics of the global climate system showing the flows of energy, water, and CO2 that are important in controlling the climate. Solar energy drives the global climate, but clouds, plants, volcanoes, ice, and the oceans all play important roles in regulating the Earth's greenhouse and determining what happens to the solar energy. CO2 and water are the principal greenhouse gases that absorb heat emitted from the surface and then re-radiate the heat back to the surface; this process maintains the Earth's temperature at a comfortable level.
Credit: Penn State Department of Geosciences, Modeling Earth's Climate System with STELLA
Numbers in the figure refer to the following key:
- Incoming short-wavelength solar radiation
- Reflected short-wavelength solar radiation
- Emission of long-wavelength radiation (heat) from surface
- Absorption of heat by greenhouse gases and emission of heat from the atmosphere back to the surface (the greenhouse effect)
- Emission of surface heat not absorbed by the atmosphere
- Evaporation cools the surface, adds water to the atmosphere
- Condensation of water vapor releases heat to the atmosphere, precipitation returns water to the surface
- Evapotranspiration by plants cools the surface
- Chemical weathering of rocks consumes atmospheric CO2
- Oceans store and transfer thermal energy
- Sedimentation of organic material and limestone (CaCO3) transfers carbon to sediment on the ocean floor
- Melting and metamorphism of sediments sends carbon back to surface
- Emission of CO2 from volcanoes
- Emission of CO2 from burning fossil fuels
- Cold oceans absorb atmospheric CO2
- Warm oceans release CO2 to the atmosphere
- Photosynthesis and respiration of plants and soil exchange CO2 between the atmosphere and biosphere
The figure above includes some new words and concepts, including short-wavelength and long-wavelength radiation, that will make sense if we devote a bit of time to a review of some topics related to energy.