I think that the best environmentalist that contributed the most is Theodore Roosevelt.. Because of what he contributed like the National Parks and stuff. Without the National parks the U.S. wouldn't be nice and some animal species wouldn't be living today.
The topic I know about environmental science is mostly about earthquakes. The topic I would like to learn about is global warming. Because I am very curious about how the earths temperature is changing.
The greatest threat is probably global warming. We are going threw it right now. It can effect many things on earth.