The northern hemisphere emerged from the last ice age 14,700 years ago with about a 12 degree Celsius (22 Fahrenheit) spike in just 50 years before plunging back into icy conditions, then suddenly warming again 3,000 years later, the researchers said.

Rapid changes in atmospheric circulation -- such as where storms occurred or where the jet stream was -- coincided with each temperature shift, pointing to a potential trigger for severe climate change, the researchers said.

"We know abrupt climate change happens," said Jim White, a paleoclimatologist at the University of Colorado at Boulder in the United States, who worked on the study.

"We don't know why it happens and we don't know what to look for as a first early warning."

The researchers did not deal with current climate change, which may be rapid for humans but is actually slower than the abrupt changes they were looking into.

They did however say that the findings could give scientists clues to what may trigger sudden severe changes in the future.

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