Like most math students, federal agencies have to show their work when solving a problem. Whether managing public lands or reining in pollution, they’re expected to back up major decisions with a breakdown of the pros and cons for society—and present how data guide every conclusion. The Trump administration, however, has taken a different tack. Instead of following the numbers where they lead, experts say it’s manipulating the math in unprecedented ways to advance fossil fuel interests and harm human and wildlife health in the long term. “I think what this administration does is just a totally different beast,” says Richard Revesz, director of New York University’s Institute for Policy Integrity, a nonpartisan think tank. “The analysis they use is outside the bounds of professional judgment.” This tinkering has led to some equally far-out conclusions. Last August the U.S. Department of the Interior concluded that a major oil drilling project could actually reduce...