Our Sun is a great, big fusion reactor that combines atoms and strews out radiation in all directions. The radiation amounts to about 172 petawatts or about 5.4E24 Joules of energy at Earth’s upper atmosphere. While this is a huge amount, most of it gets re-radiated back into space. Luckily for life on Earth, the amount coming in usually equals the amount going back out; that is, there is energy balance so the Sun doesn’t fry the Earth.

Life makes the Earth unique from Mars, Venus and other worlds of our Solar System. Life has learned to absorb the energy from the Sun and use it to its own advantage. Photosynthesis gets credit for absorbing about 3E21 Joules a year. This is a tiny amount given the total. But a very important amount given the need to maintain a balance.

Over the last couple of hundred years, humans learnt to use a lot of energy. Almost a fifth that of all the plants or 5.4E20 Joules a year.  This is a chronic change that has put energy out of balance.  We’re using stores of energy in oil, coal and natural gas. Once they’re gone then what? Do we take the energy from the plants in some contrived sharing arrangement? Do we use less? Or do we take all? What’s your preference?