DOHA (Reuters) - Major nations' policies are inadequate to limit global warming and the United States is off track even in carrying out its weak pledge to limit greenhouse gas emissions, a scientific scorecard showed on Friday.
The Climate Action Tracker report, issued on the sidelines of talks among almost 200 countries in Doha about climate change, said a toughening of policies was still possible to avert damaging floods, heat waves and rising seas.
Major emitters China, the United States, the European Union and Russia all got "inadequate" ratings for their plans to help limit global warming to an agreed U.N. ceiling of below 2 degrees Celsius (3.6F) above pre-industrial times, it said.
Adding up all national pledges and taking account of rising emissions, the world was headed for a warming of about 3.3 degrees Celsius (6F), it said.
"We are off track and the United States is not likely to meet its pledge," said Niklas Hoehne of research group Ecofys, which compiles the tracker with Climate Analytics and the Potsdam Institute for Climate Impact Research.
He told Reuters that the other top emitters were on course at least to meet their promised curbs in emissions by 2020 as part of efforts to avert severe change that would disrupt water and food supplies.
President Barack Obama aims to cut U.S. emissions by 17 percent below 2005 levels by 2020. The U.S. delegation leader in Doha, Johnathan Pershing, has reaffirmed the target and said Washington has been making "enormous" efforts.
But the U.S. Senate never ratified Obama's pledge, made in 2009. Hoehne said that the United States could step up action by tightening emissions from existing coal plants, giving more incentives for renewable energy or tougher building codes.
Pershing said U.S. emissions seem to have peaked, spurred by Obama's clean energy policies. The U.S. goal is being helped by a shift to less-polluting shale gas from coal, and by an economic slowdown.
Among the biggest emitters, only Japan and South Korea had formal policies for cuts that were "sufficient". India, Brazil and Indonesia got a "medium rating," according to the scorecard.
"Two degrees is feasible. It's possible, but we have to start now, not wait until 2020 to act," said Bill Hare of Climate Analytics. "The longer you wait, the harder it gets," said Michiel Schaeffer, also of Climate Analytics.
The study projected that China's policies of restraining the growth of its emissions meant they would climb to about 14 billion tonnes by 2020 from 10 billion now. Without the measures, emissions would surge to 18.5 billion.
The averted amount, of 4.5 billion tonnes, is more than the EU's entire annual emissions and the biggest single step towards slowing climate change, the study said.
Last week, a U.N. Environment Programme study using slightly different methods came to a similar conclusion that the world was overshooting the 2C target, putting the number at between 3 and 5 C (5.4-9F).
Editing by Mark Heinrich