In a stable climate period, the amount of heat coming from the sun and elsewhere equals the amount of heat given off by the Earth. Balance, stasis.
Global warming is the result of heat coming to Earth and being trapped by greenhouse gases instead of given off by the Earth. How much heat? According to Reuters, the trapped heat is roughly 37 times the, "...heat energy produced by all human activities, from driving cars and running power plants to burning wood."
What has researchers from America's National Center for Atmospheric Research perplexed is where all that extra heat has gone.
Half of that gap is unaccounted for... It hasn't left the climate system but it hasn't been detected with satellites, ocean sensors or other technology. The rise in greenhouse gases in the atmosphere means far more energy is coming into Earth's climate system than is going out, but half of that energy is missing and could eventually reappear as another sign of climate change.
...It might lurk in deep ocean waters in areas sensors don't reach. Some of it could be the result of imprecise measurement or processing of satellite or sensor data. But the greenhouse-caused heat gap is definitely there, the authors said.
"The heat will come back to haunt us sooner or later," Trenberth said. "It is critical to track the build-up of energy in our climate system so we can understand what is happening and predict our future climate."
Brilliant. All that heat and no idea where it's gone.