Concentrations of carbon dioxide in the atmosphere between 2012 and 2013 grew at their fastest rate since 1984.
The World Meteorological Organisation (WMO) says that it highlights the need for a global climate treaty.
But the UK’s energy secretary Ed Davey said that any such agreement might not contain legally binding emissions cuts, as has been previously envisaged.
The WMO’s annual Greenhouse Gas Bulletin doesn’t measure emissions from power station smokestacks but instead records how much of the warming gases remain in the atmosphere after the complex interactions that take place between the air, the land and the oceans.
About half of all emissions are taken up by the seas, trees and living things.