No direct sun at poles for long periods of time. Atmosphere and Hydrosphere gather heat in the tropics and transport heat to the poles. Flow from high pressure to low pressure 2. Acid rain 2. Ozone depletion 3.
Acid rain lowers the pH of rainfall, runoff, soil water.
Fish fail to reproduce, trees lose their leaves, metals are leached from soils and are loosed into watersheds. Worldwide still lots of producers and users. There is a natural greenhouse effect, but Human activities are increasing the amounts of greenhouse gases in the atmosphere dramatically, far more rapidly than nature does. Water vapor - principal greenhouse gas, regionally variable concentration, anthropogenic effect complicated. Says the Satellite Microwave Measurements.