Poor people care less for the environment than wealthier people, as a general rule. So if you push more people into poverty you get a population that will care about environmental concerns less. E.g. they will overharvest fish populations, or care less about other environmental pollution because their primary concern is getting food on their table and surviving. It's like maslow's heirarchy of needs. People generally need to look after their own and their family's survival first before they look at the survival of the environment.