The world economic recession appears to have been responsible for a fall in global emissions of carbon dioxide betweem 2008 and 2009.
The Global Carbon Project, an international group of climate scientists and analysts, says that the decline of 1.3 percent was the first fall in ten years.
The report shows big regional differences. The greatest falls occurred in Japan, the UK and Russia, while China and India actually increased CO2 emissions. While US emissions fell by 6.9 percent, the country remains one of the worst offenders, second only to China.
"The abrupt decline in fossil fuel emissions by 1.3 percent in 2009 is indisputably the result of the global financial crisis," says the report.
However, it says, the decline was smaller than anticipated because the financial crisis turned out to be less severe than expected and largely only affected more developed economies.
Nevertheless, says the report, investment in clean technologies in countries such as the UK and Germany are making a measurable difference to the world's emissions.
And improvements in land maangement - partcularly in the Brazilian Amazon and Indonesia - have meant that the amount of CO2 emitted because of land use change has fallen by about 25 percent over the last decade.
"The implementation of new land policies, higher law enforcement to stop illegal deforestation, and new afforestation and regrowth of previously deforested areas have all contributed to this decline," says the report.