Richard Tol from Sussex University believes discussion over the impacts of a 2C temperature rise is largely irrelevant as the world is likely to warm by between 3-5C, because politicians at the forthcoming Paris climate summit won't be willing or able to make the scale of cuts needed to keep temperature rises under 2C. He says a rise of 4C would be undesirable but manageable for Europe and all nations rich enough to cope with the costs of adaptation. The best way of combating climate change, he told BBC News, was to maximise economic growth.
Warming feedback
Tim Lenton, professor of Earth systems science from Exeter University, told us this was a highly optimistic prognosis under a 4C rise.
"The land surface of central Europe would be quite a lot more than 4C warmer on average, changing potentially the pattern of seasonality over Europe. We would have lost the summer Arctic sea-ice, [and] would have sea-ice cover radically thinned in winters. We're seeing already that appears to have some connection to changes in the pattern of weather and weather extremes and the changes in the distribution of rivers and river flows. We might then speculate about how intense Mediterranean drying might drive... movements of people. It would be a very different Europe." Johan Rockstrom, director of the Resilience Centre at Stockholm University, warns that the further we go above 2C, the more we risk triggering irreversible effects.
"What take us to 6C are not carbon emissions, it is biosphere response. Will we be able to maintain the natural carbon sinks in the permafrost, in the rainforests, in the boreal forests, in the wetlands and in the coastal regions? Because that's where the big stores are. We emit nine gigatons of carbon per year from our burning of fossil fuels, but there's a 100 gigatons lying just under the Siberia tundra. You have many-fold larger stores of carbon in the topsoil of tropical soils, or under the ice in the Arctic.”
"If we don't manage the living ecosystems well enough they could start biting us from behind."