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Fall 2011 Vol. 11 Number 2

Table of Contents


A Conversation About America’s
Climate Choices

Participants at a public event held last spring on America’s Climate Choices, photos by Christopher White
Participants at a public event held last spring on America’s Climate Choices, photos by Christopher White
Participants at a public event held last spring on America’s Climate Choices, photos by Christopher White
Participants at a public event held last spring on America’s Climate Choices, photos by Christopher White

A suite of five National Research Council studies requested by Congress to inform the nation of its options for responding to climate change was an enormous effort, involving approximately 100 people, who included not only scientists and engineers but also economists, business leaders, an ex-governor, a former congressman, and other policy experts. The Research Council’s most comprehensive assessment of climate change to date, America’s Climate Choices, culminated this past spring with the release of the final report and a conversation on the topic with host Heidi Cullen, vice president of external communications for Climate Central, and nine of the report’s authors. Echoing their findings, the committee members stressed that action is needed to manage climate change risks, including limiting the magnitude of climate change and preparing to adapt to its impacts.

In these reports, said committee chair Albert Carnesale, “we reaffirmed the conclusion that climate change is occurring, that it is largely due to human actions, and that it poses a significant risk to human society and to the natural environment.”

The final report finds that scientific evidence points to human activities — especially the release of carbon dioxide and other greenhouse gases into the atmosphere — as the most likely cause for the major part of global warming that has occurred over the last several decades. Moreover, this trend cannot be explained by natural factors, and the impacts of climate change can generally be expected to intensify with warming.

The vice chair of the committee, William L. Chameides, illustrated that we need to think of our understanding of climate science as looking at a jigsaw puzzle. “We have a lot of the puzzle pieces in place, and therefore we know the basic picture.”

While climate change is inherently a global issue requiring an international response, the report focused on the charge from Congress to identify steps and strategies that U.S. decision makers could adopt now.

“In order to be successful at all of this, it has to be a nationally coordinated effort,” Carnesale said. “That’s not the same as a nationally directed effort, but we do require coordination to make sure we can learn from each other and put the pieces together most effectively.”

“We know there are risks out there. We know those risks are serious. And we know they are getting worse,” Chameides asserted. If you expect a flood and the water is rising, he said, “you don’t wait for the expert to tell you how high the water is going to get. You get out the sandbags, and you develop an evacuation plan. It’s time for us to begin to develop our plan for prevention — for limiting — and our plan for adaptation.”

Other committee members who participated in the conversation discussed how substantial reductions of greenhouse gas emissions should be part of the national response. Although the exact magnitude and speed of reductions will depend on how much risk society deems acceptable, it would be imprudent to delay taking action. The most efficient way to accelerate reductions is through a nationally uniform price on greenhouse gas emissions with a price trajectory sufficient to spur investments in energy efficiency and low-carbon technologies, the report says.

In addition to the capstone event, a new exhibit at the Koshland Science Museum is based in part on the America’s Climate Choices studies. Earth Lab: Degrees of Change has interactive components that allow visitors to explore the impacts of climate change and take on the role of decision makers who identify priorities, evaluate trade-offs, and decide how to respond to climate change.
-- Jennifer Walsh & William Kearney

Watch the video of the Conversation on America’s Climate Choices or read the report series online. For more information on the Koshland Science Museum, visit

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Copyright 2011 by the National Academy of Sciences