Carbon dioxide emissions have less impact on the global average temperature than has been claimed by the UN’s climate change advisory body, according to a study.
The authors found that warming of the atmosphere was likely to occur more slowly than predicted by the Intergovernmental Panel on Climate Change.
The study, published in the journal Climate Dynamics, found that if the amount of CO2 in the atmosphere doubled, the temperature would rise by up to 1.8C over 70 years. The IPCC said in its report last year that the increase would be up to 2.5C.
The difference is significant because if the new paper is correct, the emissions cuts needed to prevent a dangerous rise in temperature could take place more slowly than governments have proposed.
Nicholas Lewis, an independent scientist who co-authored the paper with Professor Judith Curry, of Georgia Institute of Technology, in the US, said: “Our results strongly suggest complex global climate models used for warming projections are over sensitive to rises in CO2 concentrations.”
Bob Ward, policy director at the Grantham Institute on Climate Change at London School of Economics, said: “I expect that climate change ‘sceptics’ will attempt to oversell the significance of this paper. In fact, it shows that the estimates by the IPCC, which take account of all methods for determining the short-term and long-term climate sensitivity, are robust, and that the current rate of growth in greenhouse gas levels in the atmosphere will create very large risks of global warming.”