Why not? Is it because you're wise enough to know that worrying will get you nowhere, or is it because you think the prognosis for the destruction of land and air has changed for the better in recent years?
We don't have the will to do anything about it. The ozone layer was one thing. Who cares all that much about CFCs? But our current situation has to do with fossil fuels, pesticides, toxic waste . . .. There's too much profit to be made in all of that. We can't even act to save our bee population, which is about as short-sighted as it gets.