Research from Bristol university has found a new explanation for the formation of the Antartic icecap.

A team of scientists from Bristol, Cardiff and Texas universities travelled to Stakishari, a small East African village, to make the discovery.

There they extracted micro-fossils from rocks, which revealed the level of carbon dioxide in the Earth's atmosphere at the time of the formation of the icecap 33 and a half million years ago.

Geologists have long speculated that the formation of the Antarctic icecap was caused by a gradually diminishing natural greenhouse effect.

The study's findings, published in Nature online, show that atmospheric CO2 started to decline about 34 million years ago.

This was during the period known to geologists as the Eocene – Oligocene climate transition.

The ice sheet then began to form about 33.5 million years ago when CO2 in the atmosphere reached about 760 parts per million.

Dr Gavin Foster, from the University of Bristol and a co-author on the paper, said: "We have, for the first time, been able to reconstruct the concentration of CO2 across the Eocene-Oligocene boundary."

The new findings will add to the debate around rising CO2 levels when the UN Climate Conference meets in Copenhagen later this year.