's 1770 map of the
Gulf Stream Early history Humans first acquired knowledge of the waves and currents of the
seas and
oceans in pre-historic times. Observations on
tides were recorded by
Aristotle and
Strabo in 384–322 BC. Early exploration of the oceans was primarily for
cartography and mainly limited to its surfaces and of the animals that fishermen brought up in nets, though depth soundings by lead line were taken. The Portuguese campaign of Atlantic navigation is the earliest example of a systematic scientific large project, sustained over many decades, studying the currents and winds of the Atlantic. The work of
Pedro Nunes (1502–1578) is remembered in the navigation context for the determination of the loxodromic curve: the shortest course between two points on the surface of a sphere represented onto a two-dimensional map. When he published his "Treatise of the Sphere" (1537), mostly a commentated translation of earlier work by others, he included a treatise on geometrical and astronomic methods of navigation. There he states clearly that Portuguese navigations were not an adventurous endeavour:
"nam se fezeram indo a acertar: mas partiam os nossos mareantes muy ensinados e prouidos de estromentos e regras de astrologia e geometria que sam as cousas que os cosmographos ham dadar apercebidas (...) e leuaua cartas muy particularmente rumadas e na ja as de que os antigos vsauam" (were not done by chance: but our seafarers departed well taught and provided with instruments and rules of astrology (astronomy) and geometry which were matters the cosmographers would provide (...) and they took charts with exact routes and no longer those used by the ancient). His credibility rests on being personally involved in the instruction of pilots and senior seafarers from 1527 onwards by Royal appointment, along with his recognized competence as mathematician and astronomer. will push south along the northwest bulge of Africa, while the uncertain winds where the Northeast trades meet the Southeast trades (the doldrums) leave a sailing ship to the mercy of the currents. Together, prevalent current and wind make northwards progress very difficult or impossible. It was to overcome this problem and clear the passage to India around Africa as a viable maritime trade route, that a systematic plan of exploration was devised by the Portuguese. The return route from regions south of the Canaries became the '
volta do largo' or 'volta do mar'. The 'rediscovery' of the
Azores islands in 1427 is merely a reflection of the heightened strategic importance of the islands, now sitting on the return route from the western coast of Africa (sequentially called 'volta de Guiné' and 'volta da Mina'); and the references to the
Sargasso Sea (also called at the time 'Mar da Baga'), to the west of the
Azores, in 1436, reveals the western extent of the return route. This is necessary, under sail, to make use of the southeasterly and northeasterly winds away from the western coast of Africa, up to the northern latitudes where the westerly winds will bring the seafarers towards the western coasts of Europe. The secrecy involving the Portuguese navigations, with the death penalty for the leaking of maps and routes, concentrated all sensitive records in the Royal Archives, completely destroyed by the
Lisbon earthquake of 1775. However, the systematic nature of the Portuguese campaign, mapping the currents and winds of the Atlantic, is demonstrated by the understanding of the seasonal variations, with expeditions setting sail at different times of the year taking different routes to take account of seasonal predominate winds. This happens from as early as late 15th century and early 16th:
Bartolomeu Dias followed the African coast on his way south in August 1487, while
Vasco da Gama would take an open sea route from the latitude of
Sierra Leone, spending three months in the open sea of the South Atlantic to profit from the southwards deflection of the southwesterly on the Brazilian side (and the Brazilian current going southward - Gama departed in July 1497); and
Pedro Álvares Cabral (departing March 1500) took an even larger arch to the west, from the latitude of Cape Verde, thus avoiding the summer monsoon (which would have blocked the route taken by Gama at the time he set sail). Furthermore, there were systematic expeditions pushing into the western Northern Atlantic (Teive, 1454; Vogado, 1462; Teles, 1474; Ulmo, 1486). The documents relating to the supplying of ships, and the ordering of sun declination tables for the southern Atlantic for as early as 1493–1496, all suggest a well-planned and systematic activity happening during the decade long period between
Bartolomeu Dias finding the southern tip of Africa, and Gama's departure; additionally, there are indications of further travels by Bartolomeu Dias in the area. Although
Juan Ponce de León in 1513 first identified the
Gulf Stream, and the current was well known to mariners,
Benjamin Franklin made the first scientific study of it and gave it its name. Franklin measured water temperatures during several Atlantic crossings and correctly explained the Gulf Stream's cause. Franklin and Timothy Folger printed the first map of the
Gulf Stream in 1769–1770. and
Indian Oceans, by
James Rennell Information on the currents of the
Pacific Ocean was gathered by explorers of the late 18th century, including
James Cook and
Louis Antoine de Bougainville.
James Rennell wrote the first scientific textbooks on oceanography, detailing the current flows of the
Atlantic and
Indian oceans. During a voyage around the
Cape of Good Hope in 1777, he mapped
"the banks and currents at the Lagullas". He was also the first to understand the nature of the intermittent current near the
Isles of Scilly, (now known as Rennell's Current). The tides and currents of the ocean are distinct. Tides are the rise and fall of
sea levels created by the combination of the
gravitational forces of the
Moon along with the Sun (the Sun just in a much lesser extent) and are also caused by the
Earth and
Moon orbiting each other. An ocean current is a continuous, directed movement of
seawater generated by a number of forces acting upon the water, including wind, the
Coriolis effect,
breaking waves,
cabbeling, and temperature and
salinity differences. Sir
James Clark Ross took the first modern sounding in deep sea in 1840, and
Charles Darwin published a paper on
reefs and the formation of
atolls as a result of the
second voyage of HMS Beagle in 1831–1836.
Robert FitzRoy published a four-volume report of
Beagles three voyages. In 1841–1842
Edward Forbes undertook dredging in the
Aegean Sea that founded marine ecology. The first superintendent of the
United States Naval Observatory (1842–1861),
Matthew Fontaine Maury devoted his time to the study of marine meteorology,
navigation, and charting prevailing winds and currents. His 1855 textbook
Physical Geography of the Sea was one of the first comprehensive oceanography studies. Many nations sent oceanographic observations to Maury at the Naval Observatory, where he and his colleagues evaluated the information and distributed the results worldwide.
Modern oceanography Knowledge of the oceans remained confined to the topmost few fathoms of the water and a small amount of the bottom, mainly in shallow areas. Almost nothing was known of the ocean depths. The British
Royal Navy's efforts to chart all of the world's
coastlines in the mid-19th century reinforced the vague idea that most of the ocean was very deep, although little more was known. As exploration ignited both popular and scientific interest in the polar regions and
Africa, so too did the mysteries of the unexplored oceans. The seminal event in the founding of the modern science of oceanography was the 1872–1876
Challenger expedition. As the first true oceanographic cruise, this expedition laid the groundwork for an entire academic and research discipline. In response to a recommendation from the
Royal Society, the
British Government announced in 1871 an expedition to explore world's oceans and conduct appropriate scientific investigation.
Charles Wyville Thomson and
Sir John Murray launched the
Challenger expedition. , leased from the Royal Navy, was modified for scientific work and equipped with separate laboratories for
natural history and
chemistry. Under the scientific supervision of Thomson,
Challenger travelled nearly surveying and exploring. On her journey circumnavigating the globe, Around 4,700 new species of marine life were discovered. The result was the
Report Of The Scientific Results of the Exploring Voyage of H.M.S. Challenger during the years 1873–76. Murray, who supervised the publication, described the report as "the greatest advance in the knowledge of our planet since the celebrated discoveries of the fifteenth and sixteenth centuries". He went on to found the academic discipline of oceanography at the
University of Edinburgh, which remained the centre for oceanographic research well into the 20th century. Murray was the first to study marine trenches and in particular the
Mid-Atlantic Ridge, and map the sedimentary deposits in the oceans. He tried to map out the world's ocean currents based on salinity and temperature observations, and was the first to correctly understand the nature of
coral reef development. In the late 19th century, other
Western nations also sent out scientific expeditions (as did private individuals and institutions). The first purpose-built oceanographic ship,
Albatros, was built in 1882. In 1893,
Fridtjof Nansen allowed his ship,
Fram, to be frozen in the Arctic ice. This enabled him to obtain oceanographic, meteorological and astronomical data at a stationary spot over an extended period. s (1911) FRGS commemorative plaque,
Clackmannan Cemetery 2019 In 1881 the geographer
John Francon Williams published a seminal book,
Geography of the Oceans. Between 1907 and 1911
Otto Krümmel published the
Handbuch der Ozeanographie, which became influential in awakening public interest in oceanography. The four-month 1910
North Atlantic expedition headed by
John Murray and
Johan Hjort was the most ambitious research oceanographic and marine zoological project ever mounted until then, and led to the classic 1912 book
The Depths of the Ocean. The first acoustic measurement of sea depth was made in 1914. Between 1925 and 1927 the "Meteor" expedition gathered 70,000 ocean depth measurements using an echo sounder, surveying the Mid-Atlantic Ridge. In 1934,
Easter Ellen Cupp, the first woman to have earned a PhD (at Scripps) in the United States, completed a major work on
diatoms that remained the standard taxonomy in the field until well after her death in 1999. In 1940, Cupp was let go from her position at Scripps. Sverdrup specifically commended Cupp as a conscientious and industrious worker and commented that his decision was no reflection on her ability as a scientist. Sverdrup used the instructor billet vacated by Cupp to employ Marston Sargent, a biologist studying marine algae, which was not a new research program at Scripps. Financial pressures did not prevent Sverdrup from retaining the services of two other young post-doctoral students,
Walter Munk and
Roger Revelle. Cupp's partner, Dorothy Rosenbury, found her a position teaching high school, where she remained for the rest of her career. (Russell, 2000) Sverdrup, Johnson and Fleming published
The Oceans in 1942, which was a major landmark.
The Sea (in three volumes, covering physical oceanography, seawater and geology) edited by M.N. Hill was published in 1962, while
Rhodes Fairbridge's
Encyclopedia of Oceanography was published in 1966. The Great Global Rift, running along the Mid Atlantic Ridge, was discovered by
Maurice Ewing and
Bruce Heezen in 1953 and mapped by Heezen and
Marie Tharp using bathymetric data; in 1954 a mountain range under the Arctic Ocean was found by the Arctic Institute of the USSR. The theory of seafloor spreading was developed in 1960 by
Harry Hammond Hess. The
Ocean Drilling Program started in 1966. Deep-sea vents were discovered in 1977 by
Jack Corliss and
Robert Ballard in the submersible . In the 1950s,
Auguste Piccard invented the
bathyscaphe and used the
bathyscaphe to investigate the ocean's depths. The United States
nuclear submarine made the first journey under the ice to the North Pole in 1958. In 1962 the FLIP (Floating Instrument Platform), a spar buoy, was first deployed. In 1968,
Tanya Atwater led the first all-woman oceanographic expedition. Until that time, gender policies restricted women oceanographers from participating in voyages to a significant extent. From the 1970s, there has been much emphasis on the application of large scale computers to oceanography to allow numerical predictions of ocean conditions and as a part of overall environmental change prediction. Early techniques included analog computers (such as the
Ishiguro Storm Surge Computer) generally now replaced by numerical methods (e.g.
SLOSH.) An oceanographic buoy array was established in the Pacific to allow prediction of
El Niño events. 1990 saw the start of the
World Ocean Circulation Experiment (WOCE) which continued until 2002.
Geosat seafloor mapping data became available in 1995. Study of the oceans is critical to understanding shifts in
Earth's energy balance along with related global and regional changes in
climate, the
biosphere and
biogeochemistry. The atmosphere and ocean are linked because of
evaporation and
precipitation as well as
thermal flux (and solar
insolation). Recent studies have advanced knowledge on
ocean acidification,
ocean heat content,
ocean currents,
sea level rise, the
oceanic carbon cycle, the
water cycle,
Arctic sea ice decline,
coral bleaching,
marine heatwaves,
extreme weather,
coastal erosion and many other phenomena in regards to ongoing
climate change and
climate feedbacks. In general, understanding the world ocean through further scientific study enables better
stewardship and sustainable utilization of Earth's resources. The
Intergovernmental Oceanographic Commission reports that 1.7% of the total national research expenditure of its members is focused on ocean science. ==Branches==