economics meets environment

In economics the demand curve starts out with a high price, and it goes down with quantity. The reason is because we get more benefit from the first drink of water than from the 100th. We only need so much water. Too much and it might be negative. For example, people would have paid money to have the water from Hurricane Katrina not come. The same insight reveals how we aren't increasing the wellbeing of society by having more billionares at the expense of more debtors. The billionaires can only buy so much welfare for themselves. I read in a sociology critique of economics that wellbeing stops to go up with more money after people have 8,000 dollars a year or so. For 8 billion dollars I read that everyone in the world could have fresh water. That would benefit people much more than Bill Gates having 8 billion more dollars. Our obsession with GDP is propaganda therefore. It would increase GDP tremendously to build expensive nuclear weapons and B2 bombers, destroy cities, clean up the waste very expensively, and rebuild the cities. But it wouldn't increase welfare at all. If we were able to get everyone in the world clean water, it wouldn't add to GDP, but it would help welfare tremendously. Economists don't know ecology. Their theories aren't keeping track of habitat loss and pollution. There are potential theories in economics that could help with these things such as the theory of externalities. It says that economic transactions effect more than the buyer and the seller and the price of the good should be influenced by the third part effects. For example consuming coal and oil and meat is causing global warming. If we taxed the emissions equal to the amount of damage that these transactions caused in global warming, then global warming would stop. This is an economic theory. But freemarkets won't bring the best solution. If you don't tax it and you want to stop global warming, you need more of a planned economy like the socialists or communists would build. I believe you can have a socialist democracy. I don't believe we should abandon democracy.