A candidate for president emphasizes the environment on the campaign trail. He promises to update the Clean Air Act to address a grave and growing pollution threat. He wins. Three weeks after taking office, he addresses a joint session of Congress. “The time for study alone has passed, and the time for action is now,” he declares.

If you guessed climate change was the threat and Bill Clinton or Barack Obama the speaker, guess again. The new president was George H.W. Bush, and the grave and growing threat was acid rain. Five months after uttering those words, the Bush administration sent Congress a bill that amended the Clean Air Act (CAA). Included was the architecture for the world’s first large-scale application of cap and trade to control pollution, an allowance-trading system for sulfur dioxide (SO2), the major contributor to acid rain. Bush signed the bill into law in November 1990.

via Cap and Trade Curbed Acid Rain: 7 Reasons Why It Can Do The Same For Climate Change – Forbes.