Oceanography, also known as oceanology, sea science and ocean science, is the scientific study of the oceans. It is an Earth science, which covers a wide range of topics, including ecosystem dynamics; ocean currents, waves, and geophysical fluid dynamics; plate tectonics and seabed geology; and fluxes of various chemical substances and physical properties within the ocean and across its boundaries. These diverse topics reflect multiple disciplines that oceanographers utilize to glean further knowledge of the world ocean, including astronomy, biology, chemistry, climatology, geography, geology, hydrology, meteorology and physics. Paleoceanography studies the history of the oceans in the geologic past. An oceanographer is a person who studies many matters concerned with oceans, including marine geology, physics, chemistry, and biology.
The Paleocene–Eocene thermal maximum (PETM), alternatively "Eocene thermal maximum 1" (ETM1), and formerly known as the "Initial Eocene" or "Late Paleocene thermal maximum", was a time period with a more than 5–8 °C global average temperature rise across the event. This climate event occurred at the time boundary of the Paleocene and Eocene geological epochs. The exact age and duration of the event is uncertain but it is estimated to have occurred around 55.5 million years ago (Ma).
Foraminifera are single-celled organisms, members of a phylum or class of amoeboid protists characterized by streaming granular ectoplasm for catching food and other uses; and commonly an external shell of diverse forms and materials. Tests of chitin are believed to be the most primitive type. Most foraminifera are marine, the majority of which live on or within the seafloor sediment, while a smaller number float in the water column at various depths, which belong to the suborder Globigerinina. Fewer are known from freshwater or brackish conditions, and some very few (nonaquatic) soil species have been identified through molecular analysis of small subunit ribosomal DNA.
Ocean acidification is the decrease in the pH of the Earth's ocean. Between 1950 and 2020, the average pH of the ocean surface fell from approximately 8.15 to 8.05. Carbon dioxide emissions from human activities are the primary cause of ocean acidification, with atmospheric carbon dioxide levels exceeding 410 ppm. CO2 from the atmosphere is absorbed by the oceans. This produces carbonic acid which dissociates into a bicarbonate ion and a hydrogen ion. The presence of free hydrogen ions lowers the pH of the ocean, increasing acidity. Marine calcifying organisms, such as mollusks and corals, are especially vulnerable because they rely on calcium carbonate to build shells and skeletons.
Paleoceanography is the study of the history of the oceans in the geologic past with regard to circulation, chemistry, biology, geology and patterns of sedimentation and biological productivity. Paleoceanographic studies using environment models and different proxies enable the scientific community to assess the role of the oceanic processes in the global climate by the re-construction of past climate at various intervals. Paleoceanographic research is also intimately tied to paleoclimatology.
The clathrate gun hypothesis is a proposed explanation for the periods of rapid warming during the Quaternary. The hypothesis is that changes in fluxes in upper intermediate waters in the ocean caused temperature fluctuations that alternately accumulated and occasionally released methane clathrate on upper continental slopes. This would have had an immediate impact on the global temperature, as methane is a much more powerful greenhouse gas than carbon dioxide. Despite its atmospheric lifetime of around 12 years, methane's global warming potential is 72 times greater than that of carbon dioxide over 20 years, and 25 times over 100 years. It is further proposed that these warming events caused the Bond Cycles and individual interstadial events, such as the Dansgaard–Oeschger interstadials.
Marine ecosystems are the largest of Earth's aquatic ecosystems and exist in waters that have a high salt content. These systems contrast with freshwater ecosystems, which have a lower salt content. Marine waters cover more than 70% of the surface of the Earth and account for more than 97% of Earth's water supply and 90% of habitable space on Earth. Seawater has an average salinity of 35 parts per thousand of water. Actual salinity varies among different marine ecosystems. Marine ecosystems can be divided into many zones depending upon water depth and shoreline features. The oceanic zone is the vast open part of the ocean where animals such as whales, sharks, and tuna live. The benthic zone consists of substrates below water where many invertebrates live. The intertidal zone is the area between high and low tides. Other near-shore (neritic) zones can include mudflats, seagrass meadows, mangroves, rocky intertidal systems, salt marshes, coral reefs, lagoons. In the deep water, hydrothermal vents may occur where chemosynthetic sulfur bacteria form the base of the food web.
Bamboo coral, family Isididae, is a family of mostly deep-sea coral of the phylum Cnidaria. It is a commonly recognized inhabitant of the deep sea, due to the clearly articulated skeletons of the species. Deep water coral species such as this are especially affected by the practice of bottom trawling. These organisms may be an important environmental indicator in the study of long term climate change, as some specimens of bamboo coral have been discovered that are 4,000 years old.
There are many effects of climate change on oceans. One of the main ones is an increase in ocean temperatures. More frequent marine heatwaves are linked to this. The rising temperature contributes to a rise in sea levels. Other effects include ocean acidification, sea ice decline, increased ocean stratification and reductions in oxygen levels. Changes to ocean currents including a weakening of the Atlantic meridional overturning circulation are another important effect. All these changes have knock-on effects which disturb marine ecosystems. The main cause of these changes is climate change due to human emissions of greenhouse gases. Carbon dioxide and methane are examples of greenhouse gases. This leads to ocean warming, because the ocean takes up most of the additional heat in the climate system. The ocean absorbs some of the extra carbon dioxide in the atmosphere. This causes the pH value of the ocean to drop. Scientists estimate that the ocean absorbs about 25% of all human-caused CO2 emissions.
Ellen Thomas is a Dutch-born environmental scientist and geologist specializing in marine micropaleontology and paleoceanography. She is the emerita Harold T Stearns Professor and the Smith Curator of Paleontology of the Joe Webb Peoples Museum of Natural History at Wesleyan University, and a senior research scientist at Yale University.
James Zachos is an American paleoclimatologist, oceanographer, and marine scientist. He is currently a professor and chair of the Department of Earth and Planetary sciences at University of California, Santa Cruz where he was elected to the National Academy of Sciences in 2017. His research includes biological, chemical, and climatic evolution of late Cretaceous and Cenozoic oceans, and how past climatic conditions help predict the consequences of anthropogenic carbon emissions on future climate change.
The Arctic ocean covers an area of 14,056,000 square kilometers, and supports a diverse and important socioeconomic food web of organisms, despite its average water temperature being 32 degrees Fahrenheit. Over the last three decades, the Arctic Ocean has experienced drastic changes due to climate change. One of the changes is in the acidity levels of the ocean, which have been consistently increasing at twice the rate of the Pacific and Atlantic oceans. Arctic Ocean acidification is a result of feedback from climate system mechanisms, and is having negative impacts on Arctic Ocean ecosystems and the organisms that live within them.
Adina Paytan is a research professor at the Institute of Marine Sciences at the University of California, Santa Cruz. known for research into biogeochemical cycling in the present and the past. She has over 270 scientific publications in journals such as Science, Nature, Proceedings of the National Academy of Sciences, and Geophysical Research Letters.
Amelia E. Shevenell is an American marine geologist who specializes in high-latitude paleoclimatology and paleoceanography. She is currently a Professor in the College of Marine Science at the University of South Florida. She has made notable contributions to understanding the history of the Antarctic ice sheets and published in high-impact journals and, as a result, was awarded full membership of Sigma Xi. She has a long record of participation in international ocean drilling programs and has served in leadership positions of these organizations. Shevenell served as the elected Geological Oceanography Council Member for The Oceanography Society (2019-2021).
Human activities affect marine life and marine habitats through overfishing, habitat loss, the introduction of invasive species, ocean pollution, ocean acidification and ocean warming. These impact marine ecosystems and food webs and may result in consequences as yet unrecognised for the biodiversity and continuation of marine life forms.
Vital effects are biological impacts on geochemical records. Many marine organisms, ranging from zooplankton to phytoplankton to reef builders, create shells or skeletons from chemical compounds dissolved in seawater. This process, which is also called biomineralization, therefore records the chemical signature of seawater during the time of shell formation. However, different species have different metabolism and physiology, causing them to create their shells in different ways. These biological distinctions cause species to record slightly different chemical signatures in their shells; these differences are known as vital effects.
Pamela Hallock Muller is a scientist, oceanographer and professor at the University of South Florida in the College of Marine Science.
Joan Ann ("Joanie") Kleypas is a marine scientist known for her work on the impact of ocean acidification and climate change on coral reefs, and for advancing solutions to environmental problems caused by climate change.
Global paleoclimate indicators are the proxies sensitive to global paleoclimatic environment changes. They are mostly derived from marine sediments. Paleoclimate indicators derived from terrestrial sediments, on the other hand, are commonly influenced by local tectonic movements and paleogeographic variations. Factors governing the earth climate system include plate tectonics, which controls the configuration of continents, the interplay between the atmosphere and the ocean, and the earth's orbital characteristics. Global paleoclimate indicators are established based on the information extracted from the analyses of geologic materials, including biological, geochemical and mineralogical data preserved in marine sediments. Indicators are generally grouped into three categories; paleontological, geochemical and lithological.
A hyperthermal event corresponds to a sudden warming of the planet on a geologic time scale.
