In the midst of a stifling Washington, D.C. summer two years ago, former President Obama appeared in the White House to paint a grim picture of the challenge global warming posed to the country.

The August 2015 press conference, at which Obama announced the Clean Power Plan, was supposed to be held on the White House’s South Lawn, but it was moved indoors at the last moment, after officials decided it was too hot to do the event outside. Obama might have been tempted to reference D.C.’s heat wave in his remarks that day on global warming, but the President chose his words judiciously — careful not to overstep the scientific understanding of climate change and extreme weather. “While we can’t say any single weather event is entirely caused by climate change, we’ve seen stronger storms, deeper droughts, longer wildfire seasons,” he said.

For years, careful climate scientists — and the politicians like Obama who listened to them — have avoided saying that any particular event was directly caused by climate change, even as they called for urgent action to address the issue. But researchers now say they can use a variety of approaches to show that climate change is all but certainly causing and worsening extreme weather events.

A comprehensive new report from scientists at 13 federal agencies, published this week by the New York Times as it awaits review by the Trump administration, highlights the change in thinking. The scientists behind the report, leaders in their respective fields, say researchers can use statistical analysis, modeling and other methods to determine how much climate change increased the likelihood of a given event.

Researchers behind the report point to the sweltering heat wave that swept Europe in the summer of 2003 and Australian temperature extremes in 2013 as cases…