Major emitters, such as the United States, Canada and Russia, have ducked pledges to curtail emissions. Emerging economies like China and India — those projected to lead the world in heat-trapping emissions — also have shirked making such commitments.
Without “swift action,” the report warned, emissions would reach 58 gigatonnes in eight years.
“This will leave a gap that is now bigger than it was in earlier UNEP assessments of 2010 and 2011 and is in part as a result of projected economic growth in key developing economies and a phenomenon known as ‘double counting’ of emission offsets,” the Emissions Gap 2012 report said.
Brazil, China, India and South Africa said in a Tuesday statement that wealthier nations must demonstrate a stronger dedication to climate change, according to Reuters.
They said the Kyoto Protocol — the only legally binding international treaty for cutting greenhouse gas emissions — remains the standard-bearer for climate talks.
"Ministers reaffirmed that the Kyoto Protocol remains a key component of the international climate regime and that its second commitment period is the key deliverable for Doha, and the essential basis for ambition within the regime," the ministers from Brazil, China, India and South Africa said.
But the U.S. never adopted the accord. The Senate unanimously agreed to deny the treaty in 1997, citing its failure to place emissions caps on developing nations and its potential to undercut economic competitiveness.
And in 2011, Canada, Japan and Russia pulled out of the agreement. They too want any international climate deal to impose an emissions ceiling on emerging economies.
The treaty expires at the end of the year, and the climate talks set to begin next week likely will result in some alterations to the pact, Christiana Figueres, executive secretary of the U.N. Framework Convention on Climate Change, said in a statement.
Addressing emissions from China and India in particular could become a focal point. The two nations account for more than three quarters of the proposed 1,200 coal plants worldwide, according to a World Resources Institute report released Tuesday.
Though difficult, the U.N. report said staying under the 2 C temperature increase is still possible with current policy tools.
To curb emissions, the report recommended investing in energy efficiency upgrades in buildings and homes; enhancing urban design to incorporate public transportation, cycling and walking; expanding renewable energy; and maintaining forests.
"This report is a reminder that time is running out, but that the technical means and the policy tools to allow the world to stay below a maximum 2 degrees Celsius are still available to governments and societies,” Figueres said.
— This story was updated at 11:38 a.m.