40th Earth Day a planet-wide movement

[cnn-photo-caption image=http://i2.cdn.turner.com/cnn/2009/TECH/science/04/22/plants.pollution/art.sydney.jpg]

Kathleen Rogers
Special to CNN

More than 1 billion people all over the globe will observe the 40th anniversary of Earth Day today, which promises to be the largest since that first event in 1970. In 2010, the environmental challenges we face are global and call for new solutions.

Forty years ago we were reactive. In 1969, the year before the first Earth Day, two environmental disasters grabbed the country's attention: a massive oil spill coated the coast of Santa Barbara, California, and the Cuyahoga River in Cleveland, Ohio, grew so polluted that it actually caught fire.

Forty years later, with climate change looming and no strong international agreement in place despite the Copenhagen Climate conference, environmental activists are taking a proactive stance. They are arming themselves with the internet and social media to create another grass-roots movement for change, even larger than the first.

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