Transportation: Whether for business or pleasure, locomotion is the second largest source of U.S. CO2 emissions. International travel is also a factor. A study of cruise ships found that vacationing at sea emits 12 times more CO2 than vacationing on land. The 11-day international Copenhagen Climate Change Conference in Denmark generated 41,000 tons of CO2. U.S. delegates alone produced enough CO2 to fill 10,000 Olympic swimming pools.
Building: Industrial manufacturing emits lots of CO2, but it only accounts for 2 percent of U.S. emissions. Iron and steel manufacturing and cement production are the biggest offenders. These industries consume monumental quantities of heat energy to convert raw materials into construction products.
Deforestation: Trees are potent organisms for absorbing and removing CO2 emissions from the air. Cutting them down stops that process. Although deforestation is a minor source of increased CO2 in the U.S., loss of forestlands account for 20 percent of global CO2 emissions. Burning trees for fuel and natural decomposition of forest material also release CO2.