Philadelphians first celebrated Earth Week in 1970, but there's still work to do, advocates say
When many cities celebrated the first Earth Day in 1970, Philadelphia hosted Earth Week to take it a step further.
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When many cities celebrated the first Earth Day in 1970, Philadelphia hosted Earth Week to take it a step further.
Scientists are using a range of tools to protect the endangered wildlife that could disappear in coming decades.
A disappearing lizard population in the mountains of Arizona shows how climate change is fast-tracking the rate of extinction.
