Introduction to Oceanography
Oceanography is an interdisciplinary science in which researchers from diverse fields focus on the broad goal of understanding the ocean. Oceanography includes the study of the ocean's physical, biological, chemical, and geological characteristics. Physical oceanographers study the ocean's circulation, currents, waves, and tides. Biological oceanographers investigate marine organisms and their relationship to the environment. Chemical oceanographers analyze the chemical composition of sea water and the cycling of nutrients through the ocean system. Marine geologists explore the geologic features of the coastal zone and the ocean floor, and the processes that have formed those features. Engineers are also involved in oceanography, as they must design and plan equipment for use at sea. So too are policy makers, who enact environmental laws and regulations concerning the use and conservation of the ocean and its resources. History of ocean exploration
The birth of oceanography as a formal science began in the nineteenth century with the expedition of the H.M.S. Challenger. This converted British navy ship left Portsmouth England in 1872 and returned in 1876. Its mission, assigned by the British admiralty, was to investigate the conditions of the deep sea throughout the great oceanic basins. The ship logged almost 70,00 nautical miles on its voyage around the world. Challenger scientists took hundreds of depth soundings, discovered and described over 4,000 new species of marine life, and studied currents, temperature, and salinity of the oceans throughout the world. The expedition's report fills 50 bulky volumes. The Challenger expedition set the foundation for every major branch of oceanography and is considered the birth of modern oceanography.
Many other milestones in deep-sea ocean exploration have occurred since the Challenger voyage. In 1934, deep-sea researcher William Beebe made history with his dives in the Bathysphere, a hollow steel ball only 4' 9'' in diameter. He and two other men dove a mile down in this submersible, lowered and raised by a thin steel cable affixed to a winch on a barge. Beebe observed deep-sea fish and other marine organisms in their deep-sea habitat, an environment that no one else had ever explored firsthand.
Since Beebe's dives a number of researchers using modern submersibles have continued to discover new forms of deep-sea life. Other highlights of submersible exploration of the deep-sea have been provided by the dives of the Alvin, a small manned craft that in 1977 discovered the deep-sea hydrothermal vents.
The discovery that set the stage for the widespread exploration of the shallow ocean came in 1943, when Jacques-Yves Costeau and Emile Gagnan perfected the fully automatic compressed air Aqualung, the precursor to modern-day SCUBA systems. This technological advance opened the exploration of shallow-water ocean habitats to thousands of researchers from around the world.Why study the ocean and collect ocean data?
A first time visitor to Earth, curious about the character of the planet, might logically choose to explore the ocean before considering the continents, as the sea is easily Earth's most conspicuous feature. Seventy percent of the Earth's surface is covered by water. The ocean strongly influences our lives through its effects on weather and climate, and as a source of food, recreation, mineral resources, transportation, and military advantage. We also strongly influence the ocean through our activities and our waste products. These interactions provide compelling reasons for us to study the sea. But the impetus to study the ocean also stems from pure human curiosity about exploring the inner space of our planet.
An important contemporary reason to study the oceans is to better understand global environmental change. Many lines of evidence indicate that human activities on land, such as the burning of fossil fuels, can significantly affect climate via the greenhouse effect. As the oceans are an integral part of the Earth's climate system, understanding the greenhouse effect and other aspects of global environmental change requires that we study the ocean as well as the atmosphere and land. For instance, carbon dioxide (CO2) is one of the main greenhouse gases. We release carbon dioxide to the atmosphere by driving cars, heating and cooling buildings, and running factories. But not all the carbon dioxide we release to the atmosphere stays there. About half of the carbon dioxide dissolves into ocean. This dissolved carbon dioxide can also return to the atmosphere. Thus the ocean can act as both a sink and a source for atmospheric carbon dioxide, and it becomes important to better understand and quantify the ocean's role in the global carbon cycle.