The time has come to stop debating the reality of climate change and do something about it, according to America’s Climate Choices, an exhaustive National Research Council report that examines global warming's U.S. impacts and what might be done to address them.

The report—which is the culmination of four previous panel reports on climate science, mitigation, adaptation, and policy—swept aside spurious debate and focused on the “pressing need for substantial action,” including an extreme reduction in greenhouse gas emissions.

“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 stated. “In the committee’s judgment there are many reasons why it is imprudent to delay actions that at least begin the process of substantially reducing emissions.”

While the conclusion is less than shocking to anyone who has followed the climate change debate, the sense of urgency expressed by the authors is a decided departure from previous reports.

“The committee cited many reasons for not waiting, including that the faster emissions are reduced, the lower the risks,” according to a National Academies statement. “And because the effects of greenhouse gases can take decades to manifest and then persist for hundreds or even thousands of years, waiting for impacts to occur before taking action will likely be too late for meaningful mitigation. Beginning emissions reductions soon will also lower the pressure to make steeper and costlier cuts later.”

The report, which was authored by a committee of scientists, industry leaders, policy experts, and lawmakers, also recommended that the nation invest more aggressively in alternative energy strategies, coordinate mitigation activities, and work proactively with other nations to ensure U.S. progress isn’t for naught.

“America's response to climate change is ultimately about making choices in the face of risk," said William L. Chameides, committee vice chair and dean of Duke University's Nicholas School of the Environment. “Risk management strategies must be durable enough to promote sustained progress yet sufficiently flexible to take advantage of new knowledge and technologies.”