The total energy consumption of humanity is roughly 10 terawatts (10 million million watts) (Fogg, 1995, p. 67). This includes all energy sources (nuclear, fossil fuels, renewable energy), used for all purposes (electricity, heating, transportation, manufacturing). Almost all of this is eventually released as heat to the environment.You be the judge. This is not to say we shouldn't conserve, explore options, and be aware of how we are treating the planet. But one must ask why the commotion. If global warming continues, and becomes a real problem for man, we should be adapting, not destroying our economy trying to change what we probably can't change anyway.
The total amount of sunlight absorbed by the Earth is about 50,000 terawatts, or 5,000 times the energy used by humanity.
So you see, the amount of heat released by humanity is extremely small compared to the amount of heat released by the absorbtion of sunlight. But that doesn't quite answer the question: we want to know how artificial sources compare to global warming, which is small compared to total solar absorbtion.
The greenhouse effect reduces the atmosphere's ability to let heat at the surface escape to space. It works by trapping some of the heat released from the Earth's surface, and re-radiating it back down toward the surface again. This extra heat warms the Earth's surface. This is a natural process, but by releasing carbon dioxide and other gases into the atmosphere, we are increasing it. Estimates of the amount are not precise, but our best guess (IPCC WG1 Assessment, 2001, p. 37) is that the human contribution to the greenhouse effect supplies an extra 300 terawatts to the Earth's surface.
Source Global heating (Terawatts)
Human-caused Greenhouse Effect 300
Human energy production 10
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