Near-Term Acceleration in the Rate of Temperature Change
Human-driven climate changes, which are expected to impact human and natural systems, are often expressed in terms of global-mean temperature. Much attention also is given to the interannual variability and rates of change of global average temperatures. Given that faster rates of change result in less time for human and natural systems to adapt, scientists at Pacific Northwest National Laboratory’s Joint Global Change Research Institute performed an analysis using global model simulations that indicate the world is entering a period where multidecadal rates of change are becoming larger than those seen over the last millennium. They found that current trends in greenhouse gas and aerosol emissions are now moving the Earth system into a new regime, in terms of multidecadal rates of change that are unprecedented for at least the last 1,000 years. In the Climate Model Intercomparison Project phase 5 (CMIP5) archive over 40-year periods, the rate of global-mean temperature increases to 0.25±0.05 (1s) °C per decade by 2020, that, in turn, represents an unprecedented rate of change that has not been experienced at least for the past 1 to 2 millennia. Increases in greenhouse gas forcing, coupled with the decreasing influence of atmospheric aerosol particles, are now driving the climate system into this new state. Regional rates of change in Europe, North America, and the Arctic are higher than the global average. These findings show the need for research on the impacts of such near-term rates of change. Support for this analysis was provided through the Integrated Assessment Research Program, a program of the Department of Energy’s Office of Biological and Environmental Research, and the Global Technology Strategy Project, a public-private collaboration.
Smith, S. J., J. A. Edmonds, C. A. Hartin, A. Mundra, and K. V. Calvin. 2015. “Near-Term Acceleration in the Rate of Temperature Change,” Nature Climate Change, DOI: 10.1038/nclimate2552.