A goal to limit global warming to "below" two degrees Celsius is opening a new rift for 2010 talks on a UN climate treaty as developing nations say it means the rich must deepen cuts in greenhouse gas emissions.
An alliance of 101 developing nations and island states says the temperature target, endorsed by major emitters since the Copenhagen summit in December, is tougher than a previous goal by industrialised nations of two degrees as a maximum rise.
"Two degrees is unacceptable," said Dessima Williams, Grenada's ambassador to the UN who represents the Alliance of Small Island States that wants to limit temperatures to below 1.5 Celsius above pre-industrial times.
But rich nations and some researchers say the Copenhagen Accord's "below" two is vague – it can mean 1.999 degrees and so be indistinguishable for policy purposes from two. The accord does not lay down how the temperature goal will be reached.
"It can mean anything until we may agree on what it means concretely," European Union Climate Commissioner Connie Hedegaard said of the temperature target.
"The good thing about saying 'below 2C' is that you then have a ceiling. A number of countries say 1.5C and this has not been taken off the table," she said.
Senior officials meet in Bonn from April 9 until 11 for the first UN talks since Copenhagen to work out a new pact to succeed the Kyoto Protocol after the UN summit failed.
"We do not see a redefinition of the 'two degree C limit' through the Copenhagen Accord: in that sense we interpret it as 1.9999 degree C," said Brigitte Knopf, of the Potsdam Institute for Climate Impact Research.
The semantic dispute has huge economic implications for guiding a shift from fossil fuels towards renewable energies. The UN panel of climate scientists said in 2007 that a greenhouse gas goal consistent with two degrees Celsius would cost about three per cent of world gross domestic product by 2030. It did not work out the higher costs of 1.5.
Williams said promises for cuts in emissions outlined by developed nations so far put the world on track for a 3.9 degrees Celsius rise in temperatures that would bring droughts, floods, mudslides, heatwaves and rising sea levels. "Climate change leadership is certainly not forthcoming from actions and actors committing to such dangerous levels of emissions," she said. Hedegaard also said current targets are insufficient to meet the 2C goal.
Many analysts doubt that the next annual talks of environment ministers in Cancun, Mexico, in late 2010, will end with a treaty. One reason is that US legislation to cut emissions is stalled in the Senate. "To stay below 1.5C is probably impossible given the massive inertia of the socio-economic and biophysical systems," said Pep Canadell, Head of the Global Carbon Project at Australia's Commonwealth, Scientific and Industrial Research Organisation.
- The writer is Environment Correspondent for Reuters. The opinions expressed are his own