Controversial opinion: The US's buying power has led to global negative externalities directly tied to the cost-cutting measures needed to drive perpetually increasing profits and population growth, most of which was fueled by a strong growing economy. A long-term slump might lead to a net reduction in negative externalities, assuming there is a refocus on more efficient resource allocation in order to safeguard the health, education, safety, and employment of citizenry and environment.
I would agree, with the caveat that even pre-globalized societies tend toward exploiting resources and people when there's a strong economy supporting a demand. It's hard to find a case of an increased demand leading to increased resource utilization that doesn't end in negative externality.
