Greenhouse Gases
Sources and Trends
A large number of scientists believe that human activities, which have increased atmospheric concentrations of carbon dioxide (CO2) by one-third over the past 100 years, may be leading to an increase in global average temperatures. However, the science of "global warming" is not without challengers who argue that scientific proof is incomplete or contradictory, and that there remain many uncertainties about the nature and direction of Earth’s climate. Nevertheless, concern is growing that human activities, such as the burning of fossil fuels, industrial production, deforestation, and certain land-use practices, are increasing atmospheric concentrations of CO2 that, along with increasing concentrations…
