Public Release: 

Adjusting To Climate Shift Better Than Following Typically Advocated Plans

University of Illinois at Urbana-Champaign

CHAMPAIGN, Ill. - In the face of the large uncertainties of global warming, the best strategy is to keep a cool head and learn to adapt, a researcher at the University of Illinois says.

In a recent study, Michael Schlesinger, a U. of I. atmospheric scientist, and colleagues Robert Lempert and Steve Bankes (both of the RAND Corp.) used the new technique of exploratory modeling to compare the performance of two commonly advocated "best-estimate" prescriptive policies for responding to future climate change with the performance of a new adaptive-decision strategy.

"With the adaptive-decision strategy, we observe the climate system, we observe the damages due to climate change, and we observe the rate of change of the cost differential between fossil fuels and non-fossil fuels," Schlesinger said. "Depending upon what we see, we alter what we do."

The ability to make mid-course corrections offers a powerful advantage, Schlesinger said. "We found that the adaptive-decision strategy out-performed both the "Do-A-Little" policy and the "Emissions-Stabilization" policy for virtually the entire set of possibilities about the future."

In their study, the researchers used climate and economic models to construct a large uncertainty space around three variables: climate sensitivity, climate damage and technological innovation.

"For 96 points in the uncertainty space we determined the optimum abatement policy ­ which one would choose if there were no uncertainty ­ that minimizes the sum of the costs of realized and prevented climate damages," Schlesinger said. "We then compared the cost differential between the optimum policy and each prescriptive policy and the adaptive-decision strategy at each point."

Although each prescriptive policy performed well where the three uncertain variables were consistent with what the policy had assumed, both policies "differed significantly from the optimum policy throughout much of the uncertainty space, and incurred large costs over and above the cost of the optimum policy," Schlesinger said. "In contrast, the adaptive-decision strategy avoided such large errors, and incurred at most a small additional cost compared to the optimum policy."

While most quantitative studies of climate-change policy attempt to predict the greenhouse-gas reduction plan that will have the optimum balance of long-term costs and benefits, Schlesinger and his colleagues found that the large uncertainties associated with the climate-change problem can make the policy prescriptions of this traditional approach highly unreliable.

"By adopting an adaptive-decision strategy, policy-makers could make more reasonable and defensible choices about climate-change policy without requiring accurate or widely accepted predictions of the future," Schlesinger said.

Schlesinger presented the team's findings April 13 at a national meeting of the American Chemical Society in San Francisco.

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