Global warming/earth day questions

I have a few questions about some things I heard on the news on earth day.

First off, what are some of the effects human development have had on wildlife?

And second, what is ozone depletion and how does it affect the world's enviroments?

Development does take the homes of a lot of creatures. Granted we move a few houses into the area it seems like no harm done, perhaps a few squirrels need to find a new place of residence. But the problem is they are at greater risk to fall prey to our pets or get hit by a car. The ozone is not depleted, it is just very thin. The ozone is a protective layer that keeps us from getting fried from the sun. If we didnt have the ozone we would be a ball of fire. Personally I dont believe in the global warming thing simply because Al Gore invented it to fund his Green buisness. But we should be good stewards of the earth and be mindfull of where we build our houses and buisnesses. As far as us destroying it as the politicians would have you believe there is no credible evidence that supports it. It was all just made up to raise taxes or support their buisnesses.