NASA: "in the past, large changes in climate have happened very quickly, geologically-speaking: in tens of years, not in millions or even thousands"

Climate Change: Evidence

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.3