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Another way to look at this is that human civilization consumes a scary amount of power. Our global energy consumption in 2008 was estimated to be 474 exajoule
by wcoenen 13y ago
Another way to look at this is that human civilization consumes a scary amount of power.
Our global energy consumption in 2008 was estimated to be 474 exajoules. The total energy received by the earth from the sun during a year is about 5 million exajoules, a fraction of which reaches the surface.
So we are only a factor 10,000 away from that. At a seemingly modest 2% yearly growth rate, we could increase our energy consumption a hundredfold in two centuries, and waste heat will start to become an issue.
- saalweachter 13y agoYep, even today waste heat is equal to something like 5%[1] of the global heat gain. Still the lesser problem today, but once we bring a petawatt of clean fusion online... [1] it's been awhile since I looked up this number. Could easily be an order of magnitude lower, which is still fairly impressive.
- maxerickson 13y agoWhat is 'the global heat gain'?
- saalweachter 13y agoThe imbalance between how much energy the Earth receives (mostly from the sun, but also including terrestrial sources like radioactive decay in the Earth's core) and how much energy it radiates into space. The number I have in my head -- it's been awhile since I looked it up -- is that the imbalance is about 200 terawatts. For comparison, about 122 petawatts are absorbed from the sun, the Earth's fiery core generates about 45 terawatts, and humans currently produce around 16 terawatts. So the Earth is absorbing hundreds of petawatts, radiating hundreds of petawatts, and the tiny, tiny surplus of 200 terawatts is slowly heating the Earth (mostly the oceans). Incidentally, this heat gain could be counteracted by dumping about 12 cubic miles of ice into the ocean each day. Antarctica has about 6 million cubic miles of ice, so you'd get a good thousand years out of that strategy.
- maxerickson 13y agoSo the thing more commonly called "Earth's energy balance". Nothing I see quotes a tidy number like that and the temperature of the oceans would be a major factor in the radiative output of the planet.