A strong, credible body of scientific evidence shows that climate change is occurring, is caused largely by human activities, and poses significant risks for a broad range of human and natural systems.
As decision makers respond to these risks, the nation's scientific enterprise can contribute both by continuing to improve understanding of the causes and consequences of climate change, and by improving and expanding the options available to limit the magnitude of climate change and to adapt to its impacts.
To do so, the nation needs a comprehensive, integrated, and flexible climate change research enterprise that is closely linked with actionoriented programs at all levels. Also needed are a comprehensive climate observing system, improved climate models and other analytical tools, investments in human capital, and better linkages between research and decision making.
As a result of the growing recognition that climate change is underway and poses serious risks for both human societies and natural systems, the question that decision makers are asking has expanded from 'what is happening' to 'what is happening and what can we do to respond?' Scientific research can help answer both of these important questions.
The report reviews what the scientific community has learned about climate change and its interactions with human and natural systems in 12 areas of interest to decision makers.
It identifies advances needed to improve the effectiveness of actions taken to respond to climate change-including actions to limit its magnitude and adapt to its impacts-as well as understanding of the causes, mechanisms, and consequences of climate change.