Global warming is likely to disrupt a natural cycle of ice ages and delay the onset of the next one until about 1,00,000 years from now, scientists said on Wednesday.
In the past million years, the world has had about 10 ice ages before swinging back to warmer conditions. In the last ice age that 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. But rising man-made greenhouse gas emissions since the Industrial Revolution could mean the balmy period will last for 100,000 years.
"Humans have the power to change the climate on geological timescales," said lead author Andrey Ganopolski. Another group of scientists suggested an "Anthropocene epoch" began in the mid-20th century with factors such as nuclear tests and industrialisation.
Hans Joachim Schellnhuber, another author, said a new epoch might instead be called the 'Deglacial'.