Happy Earth Day.

Maybe we should start with a disclosure that I am Gaylord Nelson's biographer, which may give me a somewhat different perspective on Earth Day, founded by Senator Nelson (pictured), than some others.

Earth Day, as some have noted today, has not solved all of the world's environmental problems. But it has had, and continues to have, a profound impact on how people think about and relate to the environment.

Gaylord Nelson's primary goal in launching Earth Day was to get environmental issues a prominent place on this country's political agenda, and it certainly accomplished that long ago.

On the first Earth Day, seven months after Nelson announced plans for what he envisioned as a campus environmental teach-in, 20 million people -- 10 per cent of the US population at the time -- participated in some way.