The estimated gap between proposed global emission cuts and scientifically advisable emissions levels has widened, thanks to stronger-than-expected growth from key developing countries and more accurate carbon accounting.
In its "Emissions Gap Report 2012," the U.N. Environment Programme estimates that, should countries follow through on their most stringent international pledges to reduce greenhouse gas emissions, the world will still emit 8 gigatons above the 2020 limit scientists say is needed to prevent runaway global warming. \ Last year's report, by contrast, estimated a low-end gap of 6 gigatons of carbon dioxide equivalent over the 44-gigaton limit. The gap could be as much as 50 percent wider if states follow through on less ambitious pledges, the report notes, while a business-as-usual approach would likely put the world 14 gigatons over the advisable limit by 2020.
"We are actively moving in the wrong direction," said U.N. Undersecretary-General and UNEP Executive Director Achim Steiner, speaking at the report's release in London. "In terms of emissions, the world has already broken the speed limit -- now it appears to be putting its foot on the gas pedal, even though we know there is a T-junction ahead."
The report comes as nations are gearing up for the 18th session of the Conference of the Parties to the U.N. Framework Convention on Climate Change (UNFCCC), held this month in Doha, Qatar. Vulnerable nations are expected to push developed countries toward more ambitions emissions targets during the conference.
As it has done in the lead-up to other UNFCCC conferences, UNEP is calling for nations to go above and beyond their existing commitments, or risk more costly mitigation in later decades (ClimateWire, March 8).
Along with its sober assessment of global emissions trends, however, the report also points to a wide range of existing policy actions from around the world that, if scaled up, its authors say, could close the emissions gap by as much as 17 gigatons.
"Given our current trajectory, an underlying narrative may well emerge that we cannot achieve our 2-degree [Celsius] pathway goal by 2020, but I believe this report challenges that idea," Steiner said.
"For those who do not believe that radical changes are possible, we have seen in the last five to 10 years exceptional examples in achieving the transformative changes we are looking for," he added. Successful implementation of feed-in tariffs, efficiency standards, carbon accounting and other policy decisions -- many of them motivated as much by domestic as international concerns -- have created an accelerating curve of emissions reductions, he said.
How to bridge the gap?
Scientists have warned since the late 1980s that global warming above 2 degrees Celsius could have dramatic impacts on global health and economic productivity. At their current level of 49 gigatons, annual emissions are about 5 gigatons above the 2020 target laid out in the UNEP report.
Because most greenhouse gas emissions remain in the atmosphere for many decades, cumulative emissions are more important than annual emissions, said UNEP chief scientist Joseph Alcamo. There are therefore different pathways to each climate outcome, he said.
"Our scientists identified 39 different pathways" that would keep emissions below the 2-degree limit, he said. "They found that, to stay on target, global emissions have to peak before 2020. In 2030, emissions need to drop to a quarter below current levels, back to 1990 levels."
Closing the 8-gigaton gap between emissions levels pledged by world governments and the levels the UNEP recommends will be challenging, he said, considering the quantity of energy at stake -- by way of comparison, the world's entire industrial sector emits about 8 gigatons of carbon dioxide equivalent annually.