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Glacial periods have occurred about every 100,000 years, in sync with well-understood cycles of change in the way Earth orbits the Sun. These "Milankovitch cycles" affect where sunlight hits the planet, which can speed up or slow down the accumulation of ice across high latitudes.
It has been about 10,000 years since the last glacial period ended. All else being equal, another glacial period would be expected to arrive in the next several tens of thousands of years. However, the exact process is not fully understood, so we don’t know exactly when this will occur.
In contrast, the increase in human-produced greenhouse gases is proceeding rapidly, and it is already having effects that could intensify significantly in the next few decades. One analysis, published in the journal Science in 2013, shows that the warming of the last 100 years has occurred far more quickly than the gradual rise and fall of temperatures over the preceding 11,200 years. We cannot count on the arrival of the next ice age to offset the potentially catastrophic effects of human-triggered climate change over the next several centuries.