Earth science is a broad collection of sciences that address various aspects, both living and nonliving, of the earth. Scientists working in these fields must combine various scientific disciplines (physics, chemistry and biology) with math, geography and natural history. Subdivisions of earth science include environmental science, which studies populations of animals and plants in connection with their ecosystems; geology, which is the study of the Earth's crust; water science, which includes oceanography and hydrology; and atmospheric science, including climatology and weather.
Environmental science is the study of how populations of animals and plants are affected by their ecosystems. Environmental science often addresses the effects of human activities -- such as pollution, deforestation and industrialization -- on ecosystems and organisms. Other environmental fields include environmental policy, natural resources management, pollution management, hazardous materials policy and marine and wildlife management.
Geology is the study of the Earth's crust, specifically the rocky portions of the crust. When used more broadly, the term geology can also refer to the study of the natural history and structure of the earth. Geological subdisciplines include volcanology and seismology. Volcanologists study volcanoes and magma (molten rock beneath the Earth's surface), and also engage in lava mapping and geochemical monitoring. Seismologists study earthquakes and tectonic plates.
Another area of earth science is comprised of the water sciences. Oceanography is the study of saltwater bodies, while hydrology is the study of freshwater systems. These sciences address both the living and nonliving parts of aqueous ecosystems. For example, oceanographers may go on deep-sea expeditions to find new life forms or to study the chemical composition of the ocean floor.
Atmospheric science encompasses climatology and weather-related studies. Climatologists study and predict changes in the Earth's climate, such as global warming, ozone depletion and polar ice cap melting. Weather science deals with phenomena such as precipitation trends, acid rain and hurricane patterns. The effects on climate and weather by pollution, deforestation and urbanization are often addressed by atmospheric science, because of the relationship between human activities and the Earth's climate.