Carbon dioxide hits 20-million year high

The level of carbon dioxide in the atmosphere is at its highest for 20 million years, a new study has shown, provoking fresh warnings about the dangers of climate change.

The level of carbon dioxide in the atmosphere is at its highest for 20 million years, a new study has shown, provoking fresh warnings about the dangers of climate change.

The discovery by two British scientists has increased fears that CO ₂ could reach the same level as during the Eocene period 50 million years ago, when there were no ice caps and south-east England was a hot, steamy mangrove swamp.

The authors of the study, Professor Martin Palmer and Dr Paul Pearson, said man-made discharges of CO ₂ were likely to push the atmospheric concentration up to that level as early as 2100.

They stressed they were not suggesting that London would become a mangrove swamp by 2100. However, Roger Higman, a climate-change campaigner with Friends of the Earth, said: "[The report] suggests massive changes in the world's climate are likely and that the action governments have taken to date is derisory."

The findings, published today in the scientific journal Nature, come from a new technique that estimates CO ₂ levels by analysing the shells of prehistoric planktonic organismsfrom coral atolls in the Pacific.