Fossils can give information about past environmental conditions by showing the type of animal they belonged to. If a scientist found a whale fossil in a desert, he/she could assume that the desert was once an ocean as whales only live in oceans. If someone found a fossil of a lizard that inhabited trees, in the middle of the ocean, then he/she could assume that the ocean didn't exist at one point and instead, there might have been a forest in it's place. Hope this helps!
The emissions of carbon dioxide would reduce because then they will consume less gasoline. Instead of coal burning, this would reduce the overall concentrations of greenhouse gas emissions and generate energy from wind.