Answer: They all dealt with their environment differently. Farmers tried the three-field system where they grew 2/3 of their crops each year and let the other third "rest" by planting oats that would rejuvenate the soil with nitrogen. But as population increased, more land was needed so they cleared forests and drained swamps and they had to settle for less fertile land.
For people who lived in the cities, they treated their environment terribly. hey threw human waste into the streets that would then drain into the nearby water source. Wealthy individuals built water mills. Wealthy would use their land for hunting and sporty instead of survival.
Dams and canals were built and altered river flow. The growth of industry caused serious problems of pollution.