Earth science (also known as geoscience or the geosciences), is an all-embracing term for the sciences related to the planet Earth. It is arguably a special case in planetary science, being the only known life-bearing planet. There are both reductionist and holistic approaches to Earth science. The major historic disciplines use physics, mathematics, chemistry, and biology to build a quantitative understanding of the principal areas or spheres of the Earth system:
- Geology covers the rocky parts of the Earth (or lithosphere) including the planet's core, mantle, and crust. Major subdisciplines are geophysics, geochemistry, paleontology, mineralogy, petrology, stratigraphy and sedimentology.
- Oceanography, limnology, and hydrology describe the marine and freshwater domains of the watery parts of the Earth (or hydrosphere). Major subdisciplines are physical, chemical, and biological oceanography.
However, given the numerous interactions between the spheres many modern fields take an interdisciplinary approach and thus do not sit comfortably in this scheme:
- Biogeochemistry follows the cycling of elements through the spheres mediated by biological and geological processes, and especially their distribution and fluxes between reservoirs.
- Paleoceanography and Paleoclimatology use the properties of sediments, ice cores, or biological material to infer past states of the ocean, atmosphere or climate.
Furthermore, other modern disciplines known collectively as Earth system science approach the entire Earth as a system in its own right, which evolves as a result of positive and negative feedbacks between constituent systems:
- Meteorology describes, explains and predicts the weather based on the interaction of principally the ocean and atmosphere.
- Climatology describes and explains the climate in terms of the interaction of the litho-, hydro-, atmo-, cryo-, and bio- spheres.
- Gaia theories explain the behaviour of the Earth system in terms of the influence of the biosphere.
Like all other scientists, earth scientists apply the scientific method: formulate hypotheses after observation of and gathering data about natural phenomena and then test those hypotheses. In earth science, data usually plays a critical role in testing and formulating hypotheses. The systems approach, enabled by the combined use of computer models as hypotheses tested by global satellite and ship-board data, is increasingly giving scientists the ability to explain the past and possible future behaviour of the Earth system.
Partial list of the major Earth Science topics
- Cataclysmic Geology
- Economic geology
- Engineering geology
- Environmental geology
- Historical geology
- Mantle plumes
- Petroleum geology
- Physical geodesy
- Planetary geology
- Plate tectonics
- Quaternary geology
- Structural geology
- Physical oceanography
- Chemical oceanography
- Biological oceanography
- Marine Geology
- Marine Geophysics