News from Climate Dynamics
George Mason University and COLA Researchers Find Higher Global Warming Estimates To Be More Likely
Climate model simulations produce a wide range (2-4° C) of estimates of the magnitude of global warming, and it has been an open question what is the most likely magnitude of warming within that range. In a paper to appear in Geophysical Research Letters, researchers from George Mason University and the Center for Ocean-Land-Atmosphere Studies (COLA) have shown that higher estimates of global warming (4-5° C) may be more likely.
The paper, entitled "Climate Model Fidelity and Projections of Climate Change," presents a detailed mathematical analysis of the model simulations prepared for the Intergovernmental Panel on Climate Change (IPCC).
"This paper addresses one of the most important issues that faces both the scientific community and the international policy community, namely, the magnitude of global warming, because there is so much at stake for the future of humankind and the planetary ecosystem," J. Shukla, the lead author, said.
The authors, J. Shukla, T. DelSole, and J. Kinter, faculty members in the Climate Dynamics department of the George Mason College of Science, who also hold joint appointments at COLA, and their COLA colleagues M. Fennessy and D. Paolino, analyzed the results of 14 different climate models from 10 different premier laboratories in five different countries. They found that the models that have higher fidelity in simulating the present climate produce higher values of global warming. They conjecture that models that better simulate the present climate should be considered more credible in projecting the future climate change, which implies that the actual changes in global warming will be closer to the highest projected estimates among the current generation of models.
There is an ongoing debate in the climate research community about the degree to which current climate models are capable of accurately representing the Earth's climate, a characteristic termed "model fidelity" in the paper.
According to Shukla, "This is the first paper ever to define a quantitative metric of climate model fidelity and apply it to the currently available models being used in the IPCC assessment."
George Mason University and COLA have not conducted their own IPCC projections and are considered to be objective in their views on global warming. This was the first attempt by this group to analyze the IPCC model results.
In previous studies, the scientific community has been reluctant to evaluate models in relation to one another and comment on the fidelity of models, considering all model results to be equally probable. This group has decided to rank the models in terms of their ability to simulate the current climate.
Mason contacts – Robin Herron, University Relations Office 703-993-8804; rherron@gmu.edu); Paul Schopf, Associate Dean for Research and Computing, College of Science 301-595-7000; pschopf@gmu.edu)
COLA contact – Jim Kinter, Director, COLA 301-595-7000; kinter@cola.iges.org)