The Committee on America’s Climate Choices issued its final report this month, stating that “Climate change is occurring, is very likely caused by human activities, and poses significant risks for a broad range of human and natural systems.”The report includes a broad range of recommendations, including that the United States should substantially reduce greenhouse gas (GHG) emissions as soon as possible, start to make adaptation plans, continue research efforts to better understand climate change, and engage on an international level to address the global scale of the problem.
The Committee was formed by the National Research Council (NRC) in response to a 2008 directive from Congress. As the report explains, Congress commissioned the National Academy of Sciences to “investigate and study the serious and sweeping issues relating to global climate change and make recommendations regarding what steps must be taken and what strategies must be adopted in response to global climate change, including the science and technology challenges thereof.” A Summit on America’s Climate Choices and other public events were held in early 2009 to help frame the study, and the range of activities involved in the production of this report “involved more than 90 volunteers from a range of communities including academia, various levels of government, business and industry, other nongovernmental organizations, and the international community.”
This study differs from previous reports on climate change in several key ways, highlighted in a preface from the Committee Chair Albert Carnesale and Vice Chair William Chameides. Most notably, it was written with the public, and particularly with U.S. policymakers, as its intended audience. It was also designed to go beyond analysis and make recommendations on actions. Therefore, in addition to scientists, the committee membership also included “people with expertise and experience in public policy, government, and the private sector.” The report was produced under the auspices of the NRC’s Division on Earth and Life Sciences, Board of Atmospheric Sciences and Climate.
The committee states that the “preponderance of the scientific evidence points to human activities—especially the release of CO2 and other heat-trapping greenhouse gases (GHGs) into the atmosphere —as the most likely cause for most of the global warming that has occurred over the last 50 years or so.” It reached this conclusion by examining multiple lines of evidence, including: atmospheric concentrations of carbon dioxide that exceed anything from the last 800,000 years and are attributable to the burning of fossil fuels; analysis of physical principles and complex models that show when GHG concentrations increase, warming occurs; and analysis of observational data and models that show that current warming trends cannot be explained by natural factors.
The committee acknowledges that there is uncertainty both in how much GHG emissions will increase in the future in the absence of policies to reduce them and in how the climate system will react to these concentrations of GHGs. However, they conclude that:
“[a]lthough the exact details cannot be predicted with certainty, there is a clear scientific understanding that climate change poses serious risks to human society and many of the physical and ecological systems upon which society depends…. Thus in the judgment of the committee, the environmental, economic, and humanitarian risks of climate change indicate a pressing need for substantial actions to limit the magnitude of climate change and to prepare for adapting to its impacts.”
In their third chapter, the committee discusses the unique challenges inherent to addressing climate change. One of the primary challenges is the long time lags in the climate system. It can take decades or centuries to fully realize the effects of increased concentrations of GHGs. There are also long time lags in human remediation and adaptation mechanisms because the burning of fossil fuels is built in to so much of the way we currently live. It is also difficult to precisely calculate costs and benefits of action versus inaction because many of the natural systems that will be impacted do not have a defined market value; furthermore, the costs of action are mostly short-term, while the benefits are longer-term, which economic analyses have difficulty capturing.
To address these shortcomings in conventional modes of analysis, the committee proposes using a process of iterative risk management, which they say “emphasizes taking action now, but in doing so, being ready to learn from experience and adjust these efforts later on.” They continue: “The successful application of this approach requires broadbased continuous learning by the scientific community together with decision makers in the government, the private sector, and the general public.”
The report suggests that a comprehensive carbon-pricing system such as cap and trade or a carbon tax would be the most cost-effective solution in the long run. However, it acknowledges that this may be politically unfeasible in the current environment and that less-comprehensive solutions could be adopted in the short term, provided they do not make it more difficult to later impose broader programs. The report also encourages a national discussion on the degree of risk which is acceptable, because the answer to that question will guide many policy decisions.
The report recommends that a national adaptation strategy be implemented that would involve coordination between the federal government and state and local stakeholders. The committee also recommends a coordinated national research and development effort, both to increase our understanding of the climate system and to enhance our ability to respond to climate change. Along with that, it recommends that the national climate change response effort “include broad-based deliberative processes for assuring public and private-sector engagement with scientific analyses, and with the development, implementation, and periodic review of public policies.”
The report concludes:
“Responding to the risks of climate change is one of the most important challenges facing the United States today. Unfortunately, there is no ‘magic bullet’ for dealing with this issue; no single solution or set of actions that can eliminate the risks we face. America’s climate choices will involve political and value judgments by decision makers at all levels. These choices, however, must be informed by sound scientific analyses. This report recommends a diversified portfolio of actions, combined with a concerted effort to learn from experience as those actions proceed, to lay the foundation for sound decision-making today and expand the options available to decision makers in the future. Doing so will require political will and resolve, innovation and perseverance, and collaboration across a wide range of actors.”
The full report may be downloaded here.