France, Oct. 28 -- Record-breaking levels of greenhouse gases were recorded in the Earth's atmosphere in 2023 - reaching concentrations not seen for millions of years, the World Meteorological Organisation (WMO) warned on Monday.

In a report released ahead of the Cop29 climate summit in Azerbaijan, the WMO said the peak in greenhouse gas levels already locks in future temperature rises, even if emissions are cut to net zero.

Carbon dioxide climbed to 420 parts per million (ppm), a concentration that has not existed for three to five million years. During that era, temperatures were 3C warmer and sea levels up to 20 metres higher than today.

"Another year. Another record. This should set alarm bells ringing among decision makers," said ...