Greenhouse gas concentrations climbed to a new record in 2019 and rose again this year despite an expected drop in emissions due to Covid-19 lockdowns, the World Meteorological Organization said in Geneva on Monday, warning against complacency.

Many scientists expect the biggest annual fall in carbon emissions in generations this year as measures to contain coronavirus have grounded planes, docked ships and kept commuters at home.

However, the WMO described the projected 2020 drop as a "tiny blip" and said the resulting impact on the carbon dioxide concentrations that contribute to global warming would be no bigger than normal annual fluctuations...