Ice cores drawn from Greenland, Antarctica, and tropical mountain glaciers show that the Earth’s climate responds to changes in solar output, in the Earth’s orbit, and in greenhouse gas levels. They also show that in the past, large changes in climate have happened very quickly, geologically-speaking: in tens of years, not in millions or even thousands.

This, I believe is going to be the story of the next century, as no reversal of our global warming activity is in sight, and it might not even be feasible. IMHO, there is a very real chance that there will be fewer people in the world in 2100 than there are now. This planet is no stranger to change.