23 March 2015

Climate Change Speed-Up


Earth’s temperature changes are happening faster than historical levels and are starting to speed up. That’s the conclusion of researchers at Pacific Northwest National Laboratory, working at the Joint Global Change Research Institute (JGCRI) in Maryland. They found that the Earth is now entering a period of change that is most likely faster than what’s occurred naturally over the last thousand years. The research, published in Nature Climate Change, shows that these changes indicate the today’s world population will have to live through and adapt to a warming world. 

"In the climate model simulations, the world is just now starting to enter into a new place, where rates of temperature change are consistently larger than historical values over 40-year time spans," said Dr. Steven J. Smith, lead author of the study and interdisciplinary scientist at JGCRI. "We need to better understand what the effects of this will be and how to prepare for them."


Led by Smith, JGCRI researchers examined historical and projected changes over decades rather than centuries to determine the temperature trends that will be felt by humans alive today. Using a set of models in the Coupled Model Intercomparison Project (CMIP), the researchers were able to calculate how fast temperatures changed between 1850 and 1930, a time period when people started keeping records but when the amount of fossil fuel gases collecting in the atmosphere was low. During this time period, Earth’s temperature fluctuated due to natural variability. Over North America and Europe, those rates of change rose and fell as much as 0.2 degrees Celsius per decade.

Tackling the 40-year rates of change between 1971 to 2020, the CMIP models found the average rate of change over North America is about 0.3 degrees Celsius per decade. This is higher than can be accounted for by natural variability. And further, the near-term rates of change will not strongly depend on scenarios of future greenhouse gas emissions. Even in scenarios with lower rates of greenhouse gas emissions, the rate of climate change was still high over the coming decades.


In addition to looking at what will happen in 100 years, it’s also important to understand the kinds of change that will happen in the near-term. Rather than imagining a futuristic world with unimaginable technologies, communities and lifestyles, a 40-year time span means we see ourselves in our own homes, our current communities and environments. The research examined what will happen in the next 40 years, when today’s toddlers will be approaching their first mid-life crisis. The research found that over 40-year periods, human-caused temperature changes are now projected to stand out from natural variability. The near-term acceleration of the rate of temperature change shows an urgent need for research on the impacts of these changes, for the environment and the human-built world.


Steven J Smith
Pacific Northwest National Laboratory (PNNL)
Smith, SJ, JA Edmonds, CA Hartin, A Mundra, and KV Calvin.  2015.  "Near-Term Acceleration in the Rate of Temperature Change."  doi:10.1038/nclimate2552.

The authors are grateful for research support provided by the Integrated Assessment Research Program in the Office of Science of the US Department of Energy and the PNNL Global Technology Strategy Program. The Pacific Northwest National Laboratory is operated for DOE by Battelle Memorial Institute under contract DE-AC05-76RL01830. We acknowledge the World Climate Research Programme's Working Group on Coupled Modeling and the climate modelling groups (Supplementary Table 2) for producing and making available their model output. The US Department of Energy's Program for Climate Model Diagnosis and Intercomparison provides coordinating support for CMIP. The views and opinions expressed in this paper are those of the authors. The authors would like to thank J. Dooley and P. Applegate for helpful comments and J. Seibert for data analysis.