environmentalist

noun

1. an expert on environmental problems.
2. any person who advocates or works to protect the air, water, animals, plants, and other natural resources from pollution or its effects.
3. a person who believes that differences between individuals or groups, especially in moral and intellectual attributes, are predominantly determined by environmental factors, as surroundings, upbringing, or experience (opposed to hereditarian).

noun

1. an adherent of environmentalism
2. a person who is concerned with the maintenance of ecological balance and the conservation of the environment
3. a person concerned with issues that affect the environment, such as pollution