1. Mars had the same mass, surface features, and atmosphere as Earth? In what ways would life there be different than it is here? 2. The carbon dioxide content of Earth’s atmosphere increased? What...

1. Mars had the same mass, surface features, and atmosphere as Earth? In what ways would life there be different than it is here?

2. The carbon dioxide content of Earth’s atmosphere increased? What would happen to Earth? (This is not a completely hypothetical question, because carbon dioxide levels are increasing today.)