OSLO, (Reuters) - A global deal to combat climate change in 2015 looks more likely after promises for action by China, the United States and the European Union, but any agreement will probably be too weak to halt rising temperatures.

Delegates from almost 200 nations will meet in Lima, Peru, from Dec. 1-12 to work on the accord due in Paris in a year’s time, also spurred by new scientific warnings about risks of floods, heatwaves, ocean acidification and rising seas.

After failure to agree a sweeping U.N. treaty at a summit in Copenhagen in 2009, the easier but less ambitious aim now is a deal made up of “nationally determined” plans to help reverse a 45 percent rise in greenhouse gas emissions since 1990.

“We are in much better shape,” a year before Paris than in the run-up to Copenhagen, said Yvo de Boer, who was the U.N.’s climate chief in 2009 and now leads the Global Green Growth Institute in South Korea, which helps poor nations.

The hope is that in Paris, delegates will also work out ways to ratchet up national plans in coming years to limit average temperatures rises to an agreed ceiling of 2 degrees Celsius (3.6 Fahrenheit) above levels before the Industrial Revolution.

Temperatures have already climbed 0.85 C (1.5 F). “Not in my wildest dreams do I expect the Paris agreement to close the gap to 2 degrees,” de Boer told Reuters.

China, the United States and the European Union, which together account for more than half of world greenhouse gas emissions, have indicated they want some sort of global accord in Paris, sharply raising the chances of success for the summit.

“The prognosis is vastly better than going into Copenhagen,” said Robert Stavins, director of Harvard University’s Environmental Economics Program. “The expectations (in 2008-09) were much too high.”

CHINA FAVORS DEAL

The new, looser model for a deal is a shift from the U.N.’s existing Kyoto Protocol, which obliges the European Union and a few other rich nations to cut emissions until 2020. But Kyoto only represents about 14 percent of global emissions.

Last month, the European Union set a goal of cutting emissions by 40 percent below 1990 levels by 2030, shifting from fossil fuels toward renewable energies.

And, in a joint announcement with China’s President Xi Jinping on Nov. 11, President Barack Obama set a target of a U.S. emissions cut of 26 to 28 percent below 2005 levels by 2025 - 14 to 16 percent below the U.N. benchmark year of 1990.

China, meanwhile, said it would cap its soaring emissions by “around 2030”. It was the first time China has set a cap, but Beijing gave no numbers and studies by Chinese academics indicate emissions could soar by 30 percent by 2030. [ID:nL3N0T21YK)

And Obama’s goal faces a hostile Congress. Mitch McConnell, the incoming U.S. Senate majority leader, denounced the U.S.-China deal, as requiring nothing of China for 16 years while threatening “havoc” across in the United States.

Still, Beijing’s acceptance of a cap may change the dynamics of the U.N. negotiations. “It represents significant pressure on other large emerging economies” such as India, South Africa and Brazil, Stavins said.

This year is on track to be the warmest since records began in the 19th century, according to the U.S. National Oceanic and Atmospheric Administration - despite cold snaps like one seen in the United States in recent days.

A fall in oil prices to about $80 a barrel from $110 earlier this year may brake a shift in investments toward cleaner energies such as wind and solar power.

Among other recent shifts, donor nations promised $9.3 billion in aid for a new Green Climate Fund to help developing nations cut their greenhouse gas emissions and adapt to a changing climate.

Marlene Moses, chair of the Alliance of Small Island States, said it was an “important first step” but well short of the $15 billion developing nations had urged.

And a series of reports by the U.N.’s panel of climate scientists raised the certainty that human activities rather than natural variations are the main cause of climate change since 1950 to at least 95 percent.