Some statistics from Oliver Morton’s book on photosynthesis illustrate just how massive the energy flows involved in climate change already are. Anthropogenic climate change has increased the amount of solar radiation being retained by every square metre of the planet’s surface by 1.66 watts. In total, that is equivalent to 850 trillion watts (terawatts, TW) of power.
By comparison, a large nuclear reactor produces about 1 gigawatt (GW) of output, 1/1000th of a TW. The total energy usage of humanity (power plants, vehicles, etc) is 13 TW. At any average moment, we are therefore experiencing about 65 times more climate change power than power intentionally employed by human beings. A comparison that may be even more startling is with the flow of heat from the Earth’s core outwards – the power that drives volcanism and continental drift. That energy flow is only 40 TW – one twentieth of the climate change we have already generated.
Of course, if we keep emitting at the present rate, we will increase the 1.66 watt per metre and 850 TW numbers considerably. It is vital to understand that these numbers arise from the amount of greenhouse gasses in the atmosphere, not the amount we emit in any particular year. As such, all increases are effectively permanent, at least from the perspective of centuries. That is something to remember whenever somebody talks about ‘stabilizing emissions.’ Doing so only stabilizes the rate at which these energy statistics are increasing.