I believe people care about the environment in varying degrees.
Some folks recycle and that's as far as they go. Others may carpool or drive an electric car or they strive to run a "paperless" office. Many people volunteer to plant trees and remove trash from parks and beaches.
Truth be told the average person is a "consumer" and not a manufacturer. Governments have made strides in requiring higher standards on carbon emissions as well as more regulations when it comes to making more biodegradable products and removing lead.
I personally chose not to have children mainly because I had no desire to be a father. Nevertheless it is probably the "ultimate sacrifice" one can make for a "greener world". The average North American generates about (20 tons) of CO2-eq each year multiply that by a lifespan of 75 years and that gives you an idea of (my contribution) to the green cause.
Less people = less pollution = good for the environment.
Having said that some people will always be dissatisfied with the efforts of other people. They won't be happy until they see wholesale changes around the world. It's a noble but "unrealistic goal" very similar to "world peace". No country can dictate how another country treats it's land, water, and airspace. Since 2007 China has been the leader in carbon emissions. Their population is 1.35 billion and they are the world's largest manufacturing nation. However the U.S. is probably their biggest customer!
As I stated I believe no one wants "brown air", an ocean full of dead fish, land that is unusable, or a sun providing toxic rays. However each person will only do so much to sacrifice their standard of living. Our biggest success in the U.S. would come with having the "electric car" replace the oil and gas operated car. Needless to say the oil and automobile industries would rather find ways to get more mileage than to throw away a multi-trillion dollar industry and upset the global economy. If the electric car becomes a standard in the U.S. it won't be in our lifetime.