OSLO U.S. and Russian greenhouse gas emissions fell in 2009, according to data submitted to the United Nations, as economic decline cut the use of fossil fuels.
Other rich countries including Australia, Italy, Spain and France have also reported falls in emissions to the U.N. Climate Change Secretariat, in final data on Friday that is used to judge compliance with U.N. treaties.
"A large driver of these declines is the recession. It has made a lot of climate targets easier to achieve," said Shane Tomlinson of the E3G think-tank in London.
Many industrialized nations have yet to issue emissions data for 2009 but the signs are of a bigger overall slide than a 2.2 percent decline in 2008.
U.S. emissions fell by 6.1 percent in 2009 year-on-year to the equivalent of 6.6 billion tonnes of carbon dioxide, the biggest yearly U.S. change since the U.N. baseline year for rating emissions of 1990, the data showed.
And greenhouse gas emissions by Russia, the No. 2 industrialized emitter behind the United States, fell by 3.2 percent in 2009 to 2.2 billion tonnes.
Tomlinson said revived economic growth was likely to drive up emissions in many nations. Emissions, however, were probably lagging gross domestic product (GDP) growth, meaning a lingering benefit for fighting climate change.
The U.S. decline makes a goal set by President Barack Obama, but not approved by a hostile Senate, of cutting emissions by 17 percent below 2005 levels by 2020 easier to reach. From 2009, that planned cut now works out at 9.7 percent by 2020.
The U.S. fall was due to "a decrease in economic output resulting in a decrease in energy consumption across all sectors," according to a related statement by the U.S. Environmental Protection Agency.
It also linked the decline to a "decrease in the carbon intensity of fuels used to generate electricity due to fuel switching as the price of coal increased, and the price of natural gas decreased significantly."
U.S. GDP contracted by 2.6 percent in 2009 before growing 2.9 percent in 2010.
Russia's GDP fell 7.8 percent in 2009. Its emissions that year were 35.5 percent below the baseline year of 1990, before the collapse of smokestack Soviet industries.
The United Nations says that promised cuts in greenhouse gases so far are too weak to meet U.N. targets for averting the projected effects of climate change such as heatwaves, floods, droughts, mudslides and rising sea levels.
In November, research groups in the Global Carbon Project estimated that world emissions, also comprising poor nations led by China and India which do not report annual emissions, fell by 1.3 percent in 2009 but would rebound in 2010.