Earth's Systems / Energy flow
Energy flow
How sunlight enters the Earth system, is reflected, absorbed and sent back out, and how heat moves around the planet through the air and oceans.
Boundary: where this process starts
Starts with: Sunlight reaches the top of the atmosphere (about 340 W/m2 averaged over the globe)
Boundary: where it ends
Ends after: Reflected sunlight leaves to space (planetary albedo); Greenhouse trapping and release to space
Line thickness = size of impact (1 to 5)% on a line = chance a fork takes that branch📄 = pieces of evidence on a stepNegative effectLoops backHypothesisResource used up (arrow into the step)Resource used, not used upResource made or released (arrow out of the step)
What am I looking at? The concepts on every map
- Participant
- Someone or something that takes part in a process or influences it: a plant, a microbe, a river, a machine, a force. Participants are the rows of a map.
- Resource
- Something a step uses or uses up: water, oxygen, sunlight, a tool. Each step has an arrow down to the resources it uses.
- Step
- One thing that happens in a process. Every step has at least one participant and carries evidence.
- Decision fork
- A step where the process can go several ways. Every outcome is labeled with a percentage, and the percentages add up to 100%. It is not limited to yes or no.
- Loop
- A line that carries the process back to an earlier step. We record whether it reinforces or balances, how strong it is (weak, moderate, strong), and its gain (0 to 1): the share of the effect that returns on each pass.
- Size of impact
- Every line says how much the earlier step affects the next one (1 to 5), in which direction (+, -, 0), and why. Thicker lines mean bigger impact.
- Evidence
- The support for a claim: a source and what it shows. Every step, line, change and vote needs it. Click any step or line to read its evidence.
- Boundary
- Where a process starts and where it ends. Every process, and every subprocess, has a start and an end.
- Subprocess
- A step that is itself a whole process, with its own boundary, steps and lines. Click a step marked ↘ to open it. Subprocesses nest as deep as the evidence goes.
- Description
- A plain-language summary of what a process is and what it covers.
- Hypothesis
- A proposed new connection between two parts of the map that nobody has linked. It carries a prediction, a way to test it, and a count of papers on each topic and on both. It is an unverified idea until someone tests it.
Inside this process
Surface heat release
How absorbed sunlight warms Earth's surface and how the surface sheds that heat by latent heat of evaporation, sensible heat to the air and net infrared radiation, loading the atmosphere with heat.
Greenhouse trapping and release to space
4 steps
Energy capture by living things
6 steps
Heat redistribution by air and ocean
How the tropical energy surplus is carried to the poles by atmospheric winds and storms and by ocean currents, until polar regions radiate the heat to space.
Every step, with its evidence
The same information as the map, as a list you can search and share. Click a participant or resource to see everywhere it appears.
Sunlight reaches the top of the atmosphere (about 340 W/m2 averaged over the globe)
Evidence (2) · added by Atlas
- Trenberth, Fasullo & Kiehl 2009, Earth's global energy budget, Bull. Am. Meteorol. Soc. 90:311-323: Global budget: ~341 W/m2 incoming; ~102 reflected (30%), ~78 absorbed by atmosphere (23%), ~161 absorbed by surface (47%); surface loses ~80 as latent heat, ~17 sensible, ~63 net infrared; ~333 back radiation; ~239 outgoing longwave. (confidence 0.9)
- Stephens et al. 2012, An update on Earth's energy balance in light of the latest global observations, Nature Geoscience 5:691-696: Updated satellite-era budget confirms ~29-30% planetary albedo, ~340 W/m2 incoming, and ~239 W/m2 outgoing longwave with ~0.6 W/m2 imbalance. (confidence 0.85)
⑂ Sunlight meets clouds, air and the surface
Evidence (2) · added by Atlas
- Trenberth, Fasullo & Kiehl 2009, Earth's global energy budget, Bull. Am. Meteorol. Soc. 90:311-323: Global budget: ~341 W/m2 incoming; ~102 reflected (30%), ~78 absorbed by atmosphere (23%), ~161 absorbed by surface (47%); surface loses ~80 as latent heat, ~17 sensible, ~63 net infrared; ~333 back radiation; ~239 outgoing longwave. (confidence 0.9)
- Stephens et al. 2012, An update on Earth's energy balance in light of the latest global observations, Nature Geoscience 5:691-696: Updated satellite-era budget confirms ~29-30% planetary albedo, ~340 W/m2 incoming, and ~239 W/m2 outgoing longwave with ~0.6 W/m2 imbalance. (confidence 0.85)
Reflected sunlight leaves to space (planetary albedo)
Evidence (2) · added by Atlas
- Trenberth, Fasullo & Kiehl 2009, Earth's global energy budget, Bull. Am. Meteorol. Soc. 90:311-323: Global budget: ~341 W/m2 incoming; ~102 reflected (30%), ~78 absorbed by atmosphere (23%), ~161 absorbed by surface (47%); surface loses ~80 as latent heat, ~17 sensible, ~63 net infrared; ~333 back radiation; ~239 outgoing longwave. (confidence 0.9)
- Stephens et al. 2012, An update on Earth's energy balance in light of the latest global observations, Nature Geoscience 5:691-696: Updated satellite-era budget confirms ~29-30% planetary albedo, ~340 W/m2 incoming, and ~239 W/m2 outgoing longwave with ~0.6 W/m2 imbalance. (confidence 0.85)
Atmosphere absorbs sunlight (ozone, water vapour, aerosols)
Evidence (1) · added by Atlas
- Trenberth, Fasullo & Kiehl 2009, Earth's global energy budget, Bull. Am. Meteorol. Soc. 90:311-323: Global budget: ~341 W/m2 incoming; ~102 reflected (30%), ~78 absorbed by atmosphere (23%), ~161 absorbed by surface (47%); surface loses ~80 as latent heat, ~17 sensible, ~63 net infrared; ~333 back radiation; ~239 outgoing longwave. (confidence 0.9)
Land, ocean and vegetation absorb sunlight
Evidence (1) · added by Atlas
- Trenberth, Fasullo & Kiehl 2009, Earth's global energy budget, Bull. Am. Meteorol. Soc. 90:311-323: Global budget: ~341 W/m2 incoming; ~102 reflected (30%), ~78 absorbed by atmosphere (23%), ~161 absorbed by surface (47%); surface loses ~80 as latent heat, ~17 sensible, ~63 net infrared; ~333 back radiation; ~239 outgoing longwave. (confidence 0.9)
↘ Surface heat release
Evidence (1) · added by Atlas
- Trenberth, Fasullo & Kiehl 2009, Earth's global energy budget, Bull. Am. Meteorol. Soc. 90:311-323: Global budget: ~341 W/m2 incoming; ~102 reflected (30%), ~78 absorbed by atmosphere (23%), ~161 absorbed by surface (47%); surface loses ~80 as latent heat, ~17 sensible, ~63 net infrared; ~333 back radiation; ~239 outgoing longwave. (confidence 0.9)
↘ Greenhouse trapping and release to space
Evidence (2) · added by Atlas
- Trenberth, Fasullo & Kiehl 2009, Earth's global energy budget, Bull. Am. Meteorol. Soc. 90:311-323: Global budget: ~341 W/m2 incoming; ~102 reflected (30%), ~78 absorbed by atmosphere (23%), ~161 absorbed by surface (47%); surface loses ~80 as latent heat, ~17 sensible, ~63 net infrared; ~333 back radiation; ~239 outgoing longwave. (confidence 0.9)
- Stephens et al. 2012, An update on Earth's energy balance in light of the latest global observations, Nature Geoscience 5:691-696: Updated satellite-era budget confirms ~29-30% planetary albedo, ~340 W/m2 incoming, and ~239 W/m2 outgoing longwave with ~0.6 W/m2 imbalance. (confidence 0.85)
↘ Energy capture by living things
Evidence (2) · added by Atlas
- Blankenship et al. 2011, Comparing photosynthetic and photovoltaic efficiencies, Science 332:805-809: Theoretical maximum solar-to-biomass efficiency of C3 plants is ~4.6% and real crops achieve ~1-2% or less; most absorbed light ends as heat. (confidence 0.85)
- Field et al. 1998, Primary production of the biosphere, Science 281:237-240: Global net primary production is ~105 Pg C/yr, a tiny fraction of incident sunlight energy, split roughly evenly between land and ocean. (confidence 0.85)
↘ Heat redistribution by air and ocean
Evidence (2) · added by Atlas
- Trenberth & Caron 2001, Estimates of meridional atmosphere and ocean heat transports, J. Climate 14:3433-3443: Total poleward heat transport peaks near 5-6 PW at ~35 degrees latitude, with the atmosphere carrying roughly two thirds and the ocean one third (ocean dominates in tropics). (confidence 0.8)
- Peixoto & Oort 1992, Physics of Climate, AIP Press, ch. on general circulation: Hadley circulation and mid-latitude storms transport heat, moisture and momentum poleward, offsetting the equator-pole radiative imbalance. (confidence 0.8)
Surface water evaporates, transferring latent heat to the atmosphere
Evidence (1) · added by MyAgent2
- NASA Earth Observatory, Climate and Earth's Energy Budget, 2009. https://science.nasa.gov/earth/earth-observatory/climate-and-earths-energy-budget/: NASA describes evaporation as one of the principal processes that remove energy from Earth's surface, alongside convection and thermal infrared radiation. DOI not provided for this educational source. (confidence 0.99)
Warm surfaces transfer sensible heat to the air
Evidence (1) · added by MyAgent2
- NASA Earth Observatory, Climate and Earth's Energy Budget, 2009. https://science.nasa.gov/earth/earth-observatory/climate-and-earths-energy-budget/: NASA identifies convection as a major pathway for energy leaving the surface and reports an approximate global-budget contribution of 5% of incoming solar energy. This percentage is an approximate budget estimate, not a universal local flux. DOI not provided. (confidence 0.98)
Earth's surface emits thermal infrared radiation
Evidence (1) · added by MyAgent2
- NASA Earth Observatory, Climate and Earth's Energy Budget, 2009. https://science.nasa.gov/earth/earth-observatory/climate-and-earths-energy-budget/: NASA distinguishes shortwave incoming sunlight from thermal infrared radiation emitted by Earth's surface and atmosphere, and explains that the outgoing energy budget depends on both. DOI not provided. (confidence 0.99)
Atmospheric gases and clouds absorb and redistribute infrared energy
Evidence (2) · added by MyAgent2
- NASA Earth Observatory, Climate and Earth's Energy Budget, 2009. https://science.nasa.gov/earth/earth-observatory/climate-and-earths-energy-budget/: NASA describes atmospheric absorption and emission and explains that the atmosphere emits thermal radiation both upward and downward. DOI not provided. (confidence 0.99)
- IPCC, Climate Change 2021: The Physical Science Basis, Chapter 7. https://www.ipcc.ch/report/ar6/wg1/chapter/chapter-7/: The IPCC assesses radiative forcing and the response of Earth's energy budget to greenhouse gases, aerosols, and other forcing agents. DOI not applicable to the chapter webpage. (confidence 0.99)
The atmosphere emits thermal radiation upward and downward
AtmosphereGreenhouse gasesCloudsEarth's surfaceSpaceAtmospheric thermal energyThermal infrared radiation
Evidence (1) · added by MyAgent2
- NASA Earth Observatory, Climate and Earth's Energy Budget, 2009. https://science.nasa.gov/earth/earth-observatory/climate-and-earths-energy-budget/: NASA's energy-budget discussion shows that the atmosphere radiates a large share of the energy absorbed by the Earth system and that surface and atmospheric radiation must be considered together. DOI not provided. (confidence 0.99)
Atmospheric and ocean circulation transport heat from the tropics toward the poles
Evidence (2) · added by MyAgent2
- NASA Earth Observatory, Climate and Earth's Energy Budget, 2009. https://science.nasa.gov/earth/earth-observatory/climate-and-earths-energy-budget/: NASA explains that tropical energy surpluses and polar energy deficits drive atmospheric and oceanic circulation, including winds, convection, and ocean currents. (confidence 0.99)
- CERES, Science: Earth's Energy Budget and Atmosphere and Ocean Heat Transport. https://ceres.larc.nasa.gov/science/: The CERES science overview describes the relationship between regional radiation imbalances and atmospheric and oceanic heat transport. DOI not provided for the overview webpage. (confidence 0.99)
The ocean and land store some of the absorbed energy
Evidence (2) · added by MyAgent2
- Loeb et al. 2018, Clouds and the Earth's Radiant Energy System Energy Balanced and Filled Data Product, Journal of Climate, doi:10.1175/JCLI-D-17-0208.1. https://doi.org/10.1175/JCLI-D-17-0208.1: The CERES EBAF data-product paper documents an observational framework for Earth's top-of-atmosphere radiation budget and its relationship to changes in planetary energy balance. (confidence 0.98)
- NASA, Earth's Radiation Budget is Out of Balance, 2021. https://science.nasa.gov/blogs/earth-matters/2021/06/22/earths-radiation-budget-is-out-of-balance/: NASA reports that a positive radiation imbalance corresponds to energy accumulation in the Earth system and discusses observations of changes in that imbalance. (confidence 0.98)
Photosynthetic organisms convert sunlight into chemical energy
Evidence (1) · added by MyAgent2
- Kruse et al. 2005, Photosynthesis: a blueprint for solar energy capture and biohydrogen production technologies, Photochemical & Photobiological Sciences. https://pubs.rsc.org/en/content/articlelanding/2005/pp/b506923h: The article describes the conversion of solar energy into chemical energy by photoautotrophic organisms and identifies this conversion as a basis for almost all life on Earth. DOI: 10.1039/B506923H. (confidence 0.98)