Posted on Jul\u00a05,\u00a02013<\/h4>\n\n<\/p>\nBy TIm Radford, Climate News Network<\/b><\/p>\n
This piece first appeared at Climate News Network<\/a>.<\/i><\/p>\nLONDON\u2013Governments that agreed to try to restrict global warming to a rise of no more than 2\u00b0C may have set themselves the wrong target, according to Swiss scientists.<\/p>\n
Marco Steinacher from the University of Bern and colleagues report in Nature that the cuts in carbon dioxide emissions necessary to achieve this limit to rising temperatures won\u2019t stop sea level rise, won\u2019t halt the acidification of the oceans and won\u2019t repair the losses in agricultural productivity.<\/p>\n
They argue that a simple notch on the mercury thermometer 2\u00b0C above the pre-industrial average is not ambitious enough. The climate system involves more than just global mean atmospheric temperature: it also depends on the atmosphere\u2019s interactions with the hydrosphere, the biosphere and the geosphere.<\/p>\n
To keep the planet habitable, governments have also committed themselves to save biodiversity and at the same time to deliver food security for the 10 billion citizens who may populate the Earth later this century. All these targets will together require much deeper cuts in emissions.<\/p>\n
\u201cTherefore, temperature targets alone are unable to comprehensively limit the risks from anthropogenic emissions\u201d, they warn bluntly.<\/p>\n
The argument is a complex one: essentially they are questioning cuts that governments have yet to actually make, and fit the logic of these cuts into a global climate system that is so far not completely understood.<\/p>\n
The scientists used computer models to calculate the extent of carbon dioxide emission reductions needed to meet the proposed targets. They employed a model of the climate machinery developed at the university \u2014 they call it the Bern earth system model \u2014 and in a few weeks made the 65,000 simulations necessary to complete their study and deliver probabilities of meeting specific climate targets.<\/p>\n
\u201cWe can now show which total CO2 emissions would be tolerable in the coming decades in order to meet each and every one of the additional climate targets \u2014 for example stable production on agricultural land and limitation of ocean acidification\u201d, said Steinacher.<\/p>\n
\u201cWhen we consider all targets jointly, CO2 emissions have to be cut twice as much as if we only want to meet the two degree target.\u201d\n<\/p>\n
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renaissancechambara<\/a> (CC BY 2.0)<\/a><\/p>\n<\/span>\n<\/div>\n
By TIm Radford, Climate News Network<\/b><\/p>\n
This piece first appeared at Climate News Network<\/a>.<\/i><\/p>\n LONDON\u2013Governments that agreed to try to restrict global warming to a rise of no more than 2\u00b0C may have set themselves the wrong target, according to Swiss scientists.<\/p>\n Marco Steinacher from the University of Bern and colleagues report in Nature that the cuts in carbon dioxide emissions necessary to achieve this limit to rising temperatures won\u2019t stop sea level rise, won\u2019t halt the acidification of the oceans and won\u2019t repair the losses in agricultural productivity.<\/p>\n They argue that a simple notch on the mercury thermometer 2\u00b0C above the pre-industrial average is not ambitious enough. The climate system involves more than just global mean atmospheric temperature: it also depends on the atmosphere\u2019s interactions with the hydrosphere, the biosphere and the geosphere.<\/p>\n To keep the planet habitable, governments have also committed themselves to save biodiversity and at the same time to deliver food security for the 10 billion citizens who may populate the Earth later this century. All these targets will together require much deeper cuts in emissions.<\/p>\n \u201cTherefore, temperature targets alone are unable to comprehensively limit the risks from anthropogenic emissions\u201d, they warn bluntly.<\/p>\n The argument is a complex one: essentially they are questioning cuts that governments have yet to actually make, and fit the logic of these cuts into a global climate system that is so far not completely understood.<\/p>\n The scientists used computer models to calculate the extent of carbon dioxide emission reductions needed to meet the proposed targets. They employed a model of the climate machinery developed at the university \u2014 they call it the Bern earth system model \u2014 and in a few weeks made the 65,000 simulations necessary to complete their study and deliver probabilities of meeting specific climate targets.<\/p>\n \u201cWe can now show which total CO2 emissions would be tolerable in the coming decades in order to meet each and every one of the additional climate targets \u2014 for example stable production on agricultural land and limitation of ocean acidification\u201d, said Steinacher.<\/p>\n \u201cWhen we consider all targets jointly, CO2 emissions have to be cut twice as much as if we only want to meet the two degree target.\u201d\n<\/p>\n renaissancechambara<\/a> (CC BY 2.0)<\/a><\/p>\n <\/span>\n<\/div>\n<\/p>\n