World Meteorological Organisation figures show greenhouse gases have reached their highest recorded levels since pre-industrial times.
It says the quantities of carbon dioxide, methane, and nitrous oxide all increased in 2009.
The report shows carbon dioxide levels have increased 38% because of fossil fuel use, deforestation and changes in land use.
An increase of 158% in methane since the 18th century is said to be mostly from human activity, but 40% comes from wetlands in especially hot years. Nitrous oxide has increased by 19%, released by the oceans, burning large quantities of biomass and the use of fertiliser.
Greenpeace warns that the latest greenhouse gases figures mean there is now only 10 years left to turn around the situation.
Spokesperson Simon Boxer says that unless changes are made within the next decade, it will be too late. Mr Boxer says emissions need to be cut by 40% by 2020 to avert runway climate change.
The New Zealand National Institute of Water and Atmospheric Research scientist Mike Harvey says the figures should convince anyone who still has doubts about the existence of climate change.
The institute contributed records of carbon dioxide in the southern hemisphere, which have been taken from Baring Head near Wellington since the 1970s.