Nations are falling behind on their pledges to cut carbon emissions, making a rise in global temperatures that scientists warn could have catastrophic climate consequences more of a possibility, according to a U.N. report released Tuesday.
"Should the global community not immediately embark on wide-ranging actions to narrow the greenhouse gas emissions gap, the chance of remaining on the least-cost path to keeping global temperature rise below [2 degrees Celsius] this century will swiftly diminish and open the door to a whole host of challenges," the UN Environment Programme said.
The UN's warning to "significantly" slash emissions comes as nations prepare to meet in Warsaw next week for a major international climate conference.
Those countries' representatives will go to Poland against the backdrop of a September UN report that said scientists have never been more sure that humans are driving climate change, largely by burning fossil fuels that pump greenhouse gases into the atmosphere.
The UNEP report said the 32 countries that voluntarily agreed to set emissions reduction targets for 2020 at a 2009 climate conference in Copenhagen are struggling to honor those commitments.
Global emissions need to hit 44 gigatons of carbon dioxide by 2020 to avoid rising 2 degrees Celsius, which scientists say could lead to major climate problems — but emissions are projected to hit 59 gigatons of carbon dioxide that year, up 1 gigaton from last year's estimate.
A heavy dose of international cooperation is needed to meet the Copenhagen goals, the report said, as the UN and climate negotiators are trying to cement a new climate change accord by 2015.
"It's going to be tough to close the emissions gap by 2020," UNEP Climate Change Coordinator Merlyn van Voore said Tuesday during a conference call, adding that the report, "makes a very strong case for increased ambition leading into 2015."
International cooperation on climate change has eluded negotiators in the past.
The most recent treaty, the Kyoto Protocol, called for emissions cuts by industrial nations — but left out big polluters China and India, whose leaders argued the cuts would keep millions in poverty.
The U.S. Senate unanimously rejected the treaty in 1997, largely because of the omission of China and India. In recent years, Canada, Russia and Japan also dropped out of the climate pact.
Despite historical resistance to binding climate agreements, the U.S. now has a "much more credible" position entering the Warsaw talks because of the climate plan President Obama rolled out in June, Jennifer Morgan, director of the climate and energy program at the World Resources Institute, said during the conference call.
While it's currently behind on meeting the emissions target Obama set at Copenhagen, the administration's climate strategy "could do a lot to put the U.S. on track," Taryn Fransen, WRI project director, added during the call.
At the Copenhagen meeting, Obama called for curbing emissions 17 percent below 2005 levels, and is using that as the measuring stick for the administration's climate agenda.
Obama's plan has at its centerpiece emissions rules for new and existing coal-fired power plants. It also relies on approving new energy-efficiency regulations and boosting renewable energy production on federal lands, among other items.
"This is the first meeting where the Obama administration has had a serious plan on how it's going to implement its Copenhagen agreement," Morgan said, adding that the administration will come to Warsaw with a separate agreement with China to limit production and use of potent, short-lived heat-trapping pollutants used in refrigerants called hydrofluorocarbons.