For those who insist the Earth is just way too large for human activity to make much difference, here's a curious fact.

  • Total human enercy production/consumption is estimated at about 17.7 TW (in 2012).
  • Total radioactive decay on the planet amounts to about 20 TW.
  • And the total heat flow from Earth's interior is about 47 TW.

I was a little surprised that human energy use was in any way comparable to the natural heat flow from the whole planet so I had to check it out, but there you are. Pretty impressive and it means, right there, that we're a significant fraction of the planet's energy budget even now. Be clear, this is still pretty tiny compared to the total energy arriving at Earth from the sun which is about 173,000 TW.