Global Warming

Global warming could stave off next ice age for 100,000 years

Global warming is likely to disrupt a natural cycle of ice ages and contribute to delaying the onset of the next big freeze until about 100,000 years from now, scientists have suggested.

In the past million years, the world has had about 10 glacial periods before swinging back to warmer conditions like the present.

In the last glacial period known as the Ice Age, which ended 12,000 years ago, ice sheets blanketed what is now Canada, northern Europe and Siberia.

In a new explanation for the long-lasting plunges in global temperatures that cause ice ages, scientists pointed to a combination of long-term shifts in the Earth's orbit around the sun, together with levels of carbon dioxide in the atmosphere.

They said the planet seemed naturally on track to escape an ice age for the next 50,000 years, an unusually long period of warmth, according to the study led by the Potsdam Institute for Climate Impact Research and published in the journal Nature.

But rising man-made greenhouse gas emissions since the Industrial Revolution began in the 18th century could mean the balmy period will last for 100,000 years.

The findings suggest human influences "will make the initiation of the next ice age impossible over a time period comparable to the duration of previous glacial cycles".

Earth's orbit around the sun is oval in shape but this becomes more circular every 100,000 years and more particularly so every 400,000 years.