The meeting last June in a wood-beamed barn in Newburg, Md., an hour due south of Washington, had all the makings of a secret conclave. The guest list was confidential. No press accounts were allowed. The topic was how to pivot American agriculture to help combat climate change — an issue so politically toxic that the current administration routinely shies away from promoting crucial government research on the issue.

But this meeting represented a change. It was hosted by the U.S. Farmers and Ranchers Alliance, a group made up of the heavyweights in American agriculture. It brought together three secretaries of agriculture, including the current one, Sonny Perdue, among an A-list of about 100 leaders that included the president of the American Farm Bureau Federation — a longtime, powerful foe of federal action on climate — and CEOs of major food companies, green groups and anti-hunger advocates.