Greenhouse gas emissions have canceled the next ice age: Scientists - Global warming caused by fossil fuel emissions is blamed by scientists for raising sea levels, intensifying storms and prolonging droughts. Now there's growing evidence of a positive effect: we might have delayed the next ice age by 100,000 years or more.
The new study, which has been published in the journal Nature, suggests that we might have had a close scrape with such a period earlier in the current geological epoch known as the Holocene - and that pre-industrial human modifications of the climate through fires, and deforestation may have barely staved it off.
The study is based on the idea that there are two key factors that shape whether the earth goes into an ice age or not. There's one that humans can influence, as well as one they can't.
The factor out of our control is the Earth's Milankovitch cycles, which describe the inconsistent way in which the planet orbits the sun and spins on its axis over vast time periods. The Earth's orbit grows slowly and less elliptical, even as the angle of the planet's axial tilt, and the wobble of the poles as the planet spins, also change slightly over thousands of years.
This can affect the delivery of sunlight over different parts of the earth and the nature of the seasons - for instance, causing summers to be colder - and hence, whether it's possible to build up huge ice masses on land.
How much sun the Earth's Northern Hemisphere high latitudes receive in summer shapes whether ice can build up there over long periods, according to the study.