If the most ambitious policies to cut carbon dioxide of every country associated with last year's Copenhagen Accord on climate change are implemented by 2020, it would still be insufficient to keep the rise in global temperatures below two degrees Celsius, said a report from the United Nations Environment Program Tuesday.
"If we start at the level of emissions expected from the Copenhagen Accord pledges in 2020 and then follow the range of these pathways through to 2100, we find that they imply a temperature increase of between 2.5C and 5C before the end of the century," said the report. The scientific consensus is that temperatures shouldn't be allowed to rise more than 2C by 2100.
The most ambitious policies would bring average annual emissions of CO2 down to 49 gigatons by 2020, 5 Gt higher than it needs to be to restrict the temperature increase to 2C, said Achim Steiner, UNEP's executive director. This gap is "equal to the total emissions of the world's cars, buses and trucks in 2005," he said.
"If only the lowest ambition pledges are implemented, and if no clear rules are set in the negotiations, emissions could be around 53 Gt of CO2 equivalent in 2020," he said.
Beyond 2020, further steep cuts in CO2 emissions will still be needed, the report said.
The 5 Gt gap by 2020 could be closed by more ambitious policy options to be discussed at the U.N.'s next Climate Change Conference in Cancun, Mexico, from Nov. 29 to Dec. 10, the report said.
Last year's U.N.-sponsored Copenhagen climate change conference failed to deliver a strong agreement on limiting global warming, with some countries agreeing at the last minute on a vague and non-binding document.