By Alister Doyle, Environment Correspondent
OSLO (Reuters) - Rich nations have converged on targets of around 15 percent for cutting greenhouse gases by 2020, but recession across much of the world could impede efforts to agree a new U.N. climate pact by the end of the year.
Cuts of 15 percent from current levels would fall short of reductions advised by scientists, but the recession is limiting government ambitions, analysts say.
"We're beginning to see a rough alignment for the numbers for developed countries," said Elliot Diringer of the Pew Center on Global Climate Change in Washington.
"But the numbers don't live up to what the scientists say is needed," he said. The U.N. Climate Panel says that rich nations should cut by 25 to 40 percent below 1990 levels by 2020 to avert the worst of droughts, heatwaves, flood and rising seas.
A U.N. agreement from 2007 demands that developed nations make comparable efforts to fight warming. But analysts say the world faces huge arguments about what is a "comparable effort" in cutting emissions, mainly from burning fossil fuels, in the run-up to a meeting in Copenhagen in December to agree a new treaty to succeed the Kyoto Protocol.
Yet some say the costs of cuts may not be as high as feared.
"Within certain limits, the measures will pay for themselves," said Markus Amman of the International Institute for Applied Systems Analysis (IIASA) in Vienna. Policies such as more building insulation could save money by cutting energy use.
An IIASA calculator (http://gains.iiasa.ac.at/MEC/) shows that a 15 percent cut from 2005 levels would have negligible impact on most rich nations' gross domestic product (GDP).
OBAMA PLAN
Among national goals, President Barack Obama wants to return U.S. emissions to 1990 levels by 2020 -- a cut of 14.3 percent from 2007. China and the United States are top emitters.
The European Union, which has done more to cut emissions than the United States since 1990, plans to cut by 20 percent below 1990 levels by 2020. That works out as a 14.2 percent reduction from 2005, according to the EU Commission.
Among 2020 goals, Australia aims to cut by between five and 15 percent below 2000 levels, Canada by 20 percent below 2006.
Japan says it will unveil a mid-term target by June. Former Prime Minister Yasuo Fukuda said last year that a 14 percent cut was possible by 2020. Russia has yet to set a number.
Such cuts fall short of demands on the richer countries by developing nations, led by China and India. Developing nations are expected to slow their own rise of emissions by 2020, rather than make absolute cuts.
And the demand for comparable efforts can mean many things.
The European Commission said last month that four factors should be taken into account to ensure comparable effort -- GDP per capita, emissions per euro of economic output, population trends since 1990 and past efforts in combating warming.
Brigitte Knopf of the Potsdam Institute for Climate Impact Research said existing U.S. and EU 2020 goals were comparable in terms of their reductions from "business as usual" -- a cut of 16 percent for the U.S., 18 percent for the EU.
"But the United States would find it harder than the EU to make deeper cuts," she said. That was partly because U.S. fossil fuel reserves would be worth less if the world shifted to renewables such as wind and solar power.
The European Union has said that it is willing to cut by 30 percent below 1990 levels by 2020 if other rich nations follow suit. That would mean a 41 percent cut from businesses as usual for the United States, just 28 percent for the EU, she said.
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(Editing by Mark Trevelyan)
