This National Research Council report analyzes the impact of climate change and potential policy solutions.
Climate change is occurring, is very likely caused primarily by the emission of greenhouse gases from human activities, and poses significant risks for a range of human and natural systems. Emissions continue to increase, which will result in further change and greater risks. In the judgment of this report's authoring committee, the environmental, economic, and humanitarian risks posed by climate change indicate a pressing need for substantial action to limit the magnitude of climate change and to prepare for adapting to its impacts.
Although there is some uncertainty about future risk, there are many reasons why it is prudent to act now. The sooner that serious efforts to reduce greenhouse gas emissions proceed, the lower the risks posed by climate change, and the less pressure there will be to make larger, more rapid, and potentially more expensive reductions later. In addition, every day around the world, crucial investment decisions are made about equipment and infrastructure that can "lock in" commitments to greenhouse gas emissions for decades to come. Most actions taken to reduce vulnerability to climate change impacts are also common sense investments that will offer protection against natural climate variations and extreme events. Finally, while it may be possible to scale back or reverse many responses to climate change (if they somehow proved to be more stringent than actually needed), it is difficult or impossible to "undo" climate change, once manifested.
Current efforts of local, state, and private sector actors are important, but not likely to yield progress comparable to what could be achieved with the addition of strong federal policies that establish coherent national goals and incentives, and that promote strong U.S. engagement in international-level response efforts. The inherent complexities and uncertainties of climate change are best met by applying an iterative risk management framework and making efforts to: significantly reduce greenhouse gas emissions; prepare for adapting to impacts; invest in scientific research, technology development, and information systems; and facilitate engagement between scientific and technical experts and the many types of stakeholders making America's climate choices.