Readers of a certain age will recall that Ronald Reagan was not much of an environmentalist. Concerning the establishment of Redwood National Park, for example, he famously remarked: "A tree is a tree. How many more do you have to look at?" 

But yesterday in the New York Times, Justin Gillis wrote about the curious history and remarkable success of the Montreal Protocol to save the planet's ozone layer:

Here is a remarkable fact about global warming: It might be twice as bad right now were it not for a treaty negotiated by a conservative American president, for an entirely different purpose, based on motives no one has ever quite understood.

The treaty banned the refrigerants known as chlorofluorocarbons, which, in addition to destroying the ozone layer that protects us from dangerous radiation, turn out to be incredibly powerful greenhouse gases. Montreal was a big success on both counts, but Gillis reveals that no one is quite sure why Reagan backed the treaty. 

Mr. Reagan, with his zeal for deregulation and his conservative business principles, might have been expected to fight the idea of a global treaty. That is exactly what many of his closest aides wanted him to do. In the end, he rejected their advice and backed it, vigorously.

Why? One idea is that Mr. Reagan himself had had skin cancer, and allowed a concern for public health to triumph over ideology. Eli Lehrer, the head of a Washington think tank called the R Street Institute and a longtime Reagan admirer, offered me a simpler theory: that the man truly loved nature. He was never happier than when riding horses and chopping wood. Perhaps the science of the ozone hole just spooked him.

Elderly Sierra Club members may be skeptical, but he did spend an awful lot of time at that ranch. Perhaps the man who appointed the notorious James Watt as Interior Secretary was a nature boy himself after all. 

PAUL RAUBER is a senior editor at Sierra. He is the author, with Carl Pope, of the happily outdated Strategic Ignorance: Why the Bush Administration Is Recklessly Destroying a Century of Environmental Progress.Otherwise he is a cyclist, cook, and father of two. Follow him on Twitter @paulrauber