China agreed Saturday with the United States to scale back production of "super greenhouse gases" used in refrigerators and air conditioners in a joint bid to fight climate change.

The two nations made the pledge after a closely watched first summit between Presidents Barack Obama and Xi Jinping, who lead the world's top two emitters of greenhouse gases blamed for the planet's increasingly volatile climate.

In a statement, China and the United States "agreed to work together" through an international body to "phase down the production and consumption" of hydrofluorocarbons (HFCs), dubbed super greenhouse gases for their pollution.

The White House said that a global phasedown of HFCs could reduce carbon emissions by 90 gigatons by 2050 -- equivalent to around two full years worth of the world's greenhouse gas emissions.

China -- by far the largest producer of HFCs -- had until recently resisted efforts by the United States and other wealthy nations to scale back the super greenhouse gases, arguing that alternatives in appliances were not fully ready.

But China agreed in April to end HFC production by 2030 as part of a $385 million assistance package by wealthy countries under the Montreal Protocol, which was set up to fight the depletion of the ozone layer.

China and other developing nations such as India had initially argued that the Montreal Protocol was not the best instrument to target HFCs and that the issue should instead by handled under the Kyoto Protocol on climate change.

Some critics accused China of holding off on ending HFC production as it wanted to keep the flow of money from European Union nations that can earn credits for carbon emissions by cleaning up dirty production overseas.

The US-China statement made clear that HFCs would remain within the scope of the Kyoto Protocol and the related UN Framework Convention on Climate Change "for accounting and reporting of emissions."

The statement said that China and the United States would work together at the Montreal Protocol.

The United States, Canada and Mexico -- along with Micronesia, which greatly fears rising sea levels from climate change -- have proposed a global end to HFCs through the Montreal Protocol.

The United States and China -- which together account for more than 40 percent of greenhouse gas emissions -- have both faced international criticism for not doing more on climate change.

China has embraced solar and other green technologies, but has resisted binding commitments in talks on a successor to the Kyoto Protocol, arguing that such requirements were unfair considering its stage of development.

But China has witnessed a growing debate on requiring curbs on emissions -- not just a commitment to scale back the intensify of its own emissions, as per current policy -- as concern rises over the country's pollution woes.

Obama took office in 2009 vowing to do more on climate change after the skepticism of his predecessor George W. Bush.

But efforts backed by Obama to require caps on carbon emissions died in the US Congress, where many lawmakers from the rival Republican Party question the cost of such action and question the science behind climate change.

Representative Henry Waxman, a member of Obama's Democratic Party who helped lead the ill-fated climate legislation, called the HFC agreement "a tremendous accomplishment."

"The United States and China working together to tackle climate change is a major breakthrough," he said.

The planet has charted a slew of record hot years and some scientists link recent catastrophes -- such as superstorm Sandy in the United States, droughts in Russia and massive floods in Pakistan -- to climate change.

Warming places SE Asia, India at higher risk of flood
Paris (AFP) June 09, 2013 - Rising carbon emissions will place parts of India, China, Southeast Asia, East Africa and the northern Andes at a higher risk of extreme floods, a study published on Sunday says.

Global warming will boost the frequency at which exceptional floods occur in these regions, while eastern Europe, parts of Scandinavia, Chile and Argentina will have fewer such events, it suggests.

The estimates are based on 11 models for greenhouse-gas emissions and their impact on 29 river basins by 2100.

At the extreme end of the estimate range -- if temperatures rise by four or five degrees Celsius (seven or nine degrees Fahrenheit) -- a flood event that statistically occurred only once every one hundred years in the 20th century could return every 10 to 50 years in the most vulnerable locations.

"Many of these regions are already notorious for (being) flood-prone," said Shinjiro Kanae, a civil engineer at the Tokyo Institute of Technology, who took part in the modelling.

The "return period" of once-a-century floods reduces if warming levels by 2100 are lower, though.

The study, published in the journal Nature Climate Change, is led by Yukiko Hirabayashi of the University of Tokyo.

It is one of the most ambitious attempts to finetune estimates on where flooding will occur in a warmer world. Previous studies have used only several models, or even just one, which means the range of uncertainty is very wide.

The Japanese authors note that there remains a large margin of regional variability in their estimates. They also point out that the estimates do not take into account actions that worsen or prevent flooding.

UN members have pledged to limit warming to 2C (3.6 F) compared to pre-industrial temperatures.

But the current rise in carbon concentrations is in line with 4C or 5C (7-9 F) by 2100, a figure that many scientists say would be catastrophic for biodiversity and for hundreds of millions exposed to hunger, extreme weather or sea-level rise.