To see the tiny holes, or stomata , in the leaves through which leaves transpire water, you must look under a microscope. However, if you wrap a broad-leaf plant in clear plastic, and place it in the sunlight, in a few hours, you will see moisture or condensation clinging to the inside of the bag. This moisture was given off by the leaves much like the moisture excreted from your skin when you perspire. Trees and Climate Many human activities, such as modern farming, the burning of fossil fuels or cutting down and burning forests, release large amounts of gas into the atmosphere. These gases are referred to as greenhouse gases because they act like the glass covering of a greenhouse, absorbing solar radiation and trapping it inside.
Sunlight pentrates the atmosphere and warms the Earth's surface.
The Earth then radiates some of this heat back into the atmosphere. Some of this heat escapes into space and some is reflected back to earth as watervapor and greenhouse gases absorb it. As greenhouse gases increase more heat can be trapped near the Earth's surface This build-up of carbon dioxide could cause the planet to heat up. Trees absorb carbon dioxide to make food during the process of photosynthesis. Using energy from the sun, green plants break apart carbon dioxide and water molecules and rearrange the loose atoms to form sugar.