Much study has been devoted to the possible causes of an apparent decrease in the upward trend of global surface temperatures since 1998, a phenomenon that has been dubbed the global warming “hiatus.” Here we present an updated global surface temperature analysis that reveals that global trends are higher than reported by the IPCC, especially in recent decades, and that the central estimate for the rate of warming during the first 15 years of the 21st century is at least as great as the last half of the 20th century.

Human-induced climate change is a major and growing concern to U.S. policymakers and citizens who need the best available science to inform their decisions. This report responds to that need by synthesizing the large and growing body of science that deals with how climate is changing, and the impacts of these changes on the United States, now and in the future.

Changes in extreme weather and climate events have significant impacts and are among the most serious challenges to society in coping with a changing climate. This report provides current assessments of climate change science to inform public debate, policy, and operational decisions.