Desperately poor people focus on feeding their family and have no spare energy to support secondary concerns such as the environment.
Destitute societies also see large families as free labour and old-age insurance. Thus poverty inevitably produces growing populations and environmental degradation.
The industrial revolution, powered by abundant reliable energy from coal, oil and gas, provided rural labourers with better-paying jobs in industry and government. With kerosene tractors, iron ploughs and no draught horses to feed, farmers had more food to sell. Food prices fell, cities grew, and society supported more culture, conservation and welfare.
With increasing prosperity western families became smaller, reducing birth-rates below replacement levels thus moderating population pressure on the environment.
