Facts are stubborn things, as the administration of U.S. President Donald Trump is repeatedly discovering. While the president and many of his top appointees deny the reality of climate change, science continues to amass unmistakable evidence of its existence. The administration's refusal to acknowledge that unpleasant truth will have profound implications for the United States, doing not only great physical damage, but also affecting its economy and its leadership.

The latest indictment of Washington's ostrich-like policy is a massive study released Nov. 3, that concluded that there is "no convincing alternative explanation" for the changing climate other than "human activities, especially emissions of greenhouse gases." The Climate Science Special Report notes that warming temperatures, rising sea levels, more frequent heat waves and other extreme weather events are evidence of climate change. For an administration led by a man who declared climate change is a "hoax," whose energy secretary, Rick Perry, said only the day before the report was released that "science is still out" on whether human activity is the primary driver of climate change, and whose Environmental Protection Agency is focused on rolling back climate initiatives that are in place, including the gratuitous withdrawal from the Paris climate change agreement, the report is a head scratcher. Its conclusions shred the skepticism behind Trump policy; why then was it published?

The simple answer is because it was mandated by law. The National Climate Assessment is produced every four years by the U.S. Global Change Research Program, a group of 13 federal agencies, and analyzes human- and naturally-caused global changes. Scientists and researchers from those agencies, along with outside experts, compile the report, and it is published after an extensive review and comment process. It is considered the most comprehensive and authoritative statement on climate science by the U.S. government.