Earth; 12/23/08

New Science & Technology: How do trees affect the weather? Whether ...Trees affect our climate, and therefore our weather, in three primary ways: they lower temperatures, reduce energy usage and reduce or remove air pollutants. Each part of the tree contributes to climate control, from leaves to roots.
Leaves help turn down the thermostat. They cool the air through a process called evapotranspiration. It may seem like an invisible process to our eyes, but a large oak tree is capable of transpiring 40,000 gallons of water into the atmosphere during one year [source: USGS].