Scientists develop new approach to support future climate projections

A new approach for evaluating past climate sensitivity data has been developed by scientists to help improve comparison with estimates of long-term climate projections developed by the Intergovernmental Panel on Climate Change (IPCC). The sensitivity of global temperature to changes in the Earth's radiation balance (climate sensitivity) is a key parameter for understanding past natural climate changes as well as potential future climate change. Many palaeoclimate studies have measured natural climate changes to calculate climate sensitivity, but a lack of consistent methodologies produced a wide range of estimates as to the exact value of climate sensitivity, which hindered results. Now an international team of scientists, including Dan Lunt and Paul Valdes from the University of Bristol's School of Geographical Sciences, have developed a more consistent definition of climate sensitivity in prehistoric times. When the scientists evaluated previously published estimates for climate sensitivity from a variety of geological episodes over the past 65 million years, they found that the estimates varied over a very wide range of values. The team discovered that this wide range was almost entirely due to the fact that different researchers used different definitions. Just as biologists need taxonomy to ensure that they all talk about the same organisms, the climate scientists needed to develop a definition terminology that, applied to estimates from the past, makes those estimates compatible with estimates from climate models as used by the IPCC.