Green is often used as a synonym for environmental or ecological, especially as it relates to products and activities aimed at minimizing damage to the planet. Scientists and engineers have long had important roles in the environmental movement. Their expertise is focused on a variety of issues, including increasing energy efficiency, improving air and water quality, and sustaining natural resources. With interest in such projects growing, there should be additional opportunities for these scientists and engineers in the future. Some discussions of these occupations classify workers by environmental issue, such as air quality, solid waste management, or land conservation. Others group them by project category, such as environmental protection, environmental health and safety, and natural resources management. This article uses the latter method to describe the job duties, employment, outlook, wages, and training requirements for conservation scientists, environmental engineers, environmental scientists, and hydrologists.