> There is only one way forward: The external costs of the economic activity must be internalised. So true. Even if, as OP posted, you did something like cover

> There is only one way forward: The external costs of the economic activity must be internalised. So true. Even if, as OP posted, you did something like cover the Great Lakes in green algae, if you fail to force everyone to internalize negative externalities, it would just be a matter of time before any gains were destroyed again.