““On the daytime side of Earth, the solar radiation hitting the top fo the atmosphere deposits around 1,300 watts of power per square meter. That's about the same amount used by an electric kettle. It doesn't seem like a great deal. But add up that incoming solar radiation across one whole hemisphere of Earth, and a total of about 174 petawatts (10^15, or a quadrillion, watts) of solar power is hitting the top of the atmosphere. A colossal total of 89 petawatts of that same power is absorbed by the surface of the Earth directly. The rest is reflected by the surface, or absorbed by the atmosphere reflected by its clouds of condensed water. By human standards this is a fearsome amount of Energy. Estimates of current human energy consumption suggest that in a single year we use roughly 1.6 X 10^11 megawatt-hours, which means that with 8,760 hours in a year we are using energy at a rate of about 0.018 petawatts. All life on Earth (adding up photosynthetic organisms, water transpiration in plants, and what life gets from chemical and geophysical energy) is estimated to consume energy at a rate of between 0.1 and 5 petawatts. In other words, despite life's potent footpirnt on the planet, on a cosmic scale it's still barely sipping at what the Sun's photons rain down on us.””
