The Ocean's Role in Global Change Progress of Major Research Programs (1994) / Chapter Skim
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THE GEOLOGICAL PERSPECTIVE
THE GEOLOGICAL PERSPECTIVE
Pages 39-56
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From page 39... ...
Even with a complete understanding of today's ocean, current climate models and our ability to predict future climatic changes would still be limited. To understand past, present, and future climate change fully, we must understand the long-term, natural variability of the ocean-climate system; the sensitivity of the ocean/climate system to change; and the reliability of models to predict future climate change.
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From page 40... ...
These data provide a historical record of past environmental conditions over a range of time scales, putting present oceanic conditions into perspective. There are several potential causes and effects of climate changes.
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From page 41... ...
The four programs described below focus on research programs designed to understand past climatic and oceanic conditions and the mechanisms that drive changes in these conditions. Ocean Drilling Program How good are climate predictions?
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From page 42... ...
Since 1988, one of the ODP's major operational goals has been to obtain continuous sedimentary sections from key places in the world oceans. Partial depth transects have been collected in the western and northern Pacific Ocean, the Tyrrhenian Sea, the eastern equatorial Atlantic, the Peru Margin, the Maud Rise, the Subantarctic, the Indian Ocean, the tropical Pacific, the Santa Barbara Basin, and soon the tropical Atlantic, the subarctic Atlantic, and the Norwegian Sea.
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From page 43... ...
Because of ODP advances in analyzing past oceanic productivity through the recovery of complete sedimentary sections, it is now possible to express sedimentary data in terms of actual fluxes through time. Concurrently, under the auspices of other oceanographic programs such as JGOFS, the role of biological productivity on ocean chemistry and climate is becoming better understood.
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From page 44... ...
, ......................................... - -.-.- -.- - - - environmental variability under different climatic conditions will undoubtedly require continued scientific drilling by the ODP.
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From page 45... ...
This record is dominated by climate changes, including those induced by changes in ocean circulation, glaciation, impacts of celestial bodies (asteroids and comets) on Earth, volcanic eruptions, and plate tectonics.
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From page 46... ...
On shorter time scales, the distribution of hydrothermal activity along the mid-ocean ridge system, its episodicity and variability, play important roles in regulating ocean chemistry and circulation- two of the critical factors in predicting global climate change. Within RIDGE, there are several research initiatives that are investigating these factors through reconnaissance surveys of previously unexplored parts of the global ridge system, development of response strategies to the detection of events on mid-ocean ridges, and detailed measurements of temporal variations at a single "observatory" site.
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From page 47... ...
One of the major challenges for the RIDGE program is to develop practical and reliable methods for detecting, locating, and responding to transient ridge crest phenomena, such as volcanic eruptions, tectonic activity, or catastrophic releases of heat or chemical mass into the water column (Box 111. Monitoring of subaerial eruptions in Hawaii and Iceland has led to major advances in understanding how these systems work.
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From page 48... ...
Estimation of the energy and chemical fluxes associated with ridge processes is vital to assessing their impact on global climate change. However, these estimates require characterization of the tectonic structure, geochemistry, biology, and energy fluxes of the midocean ridge on a global scale a goal possible only in the context of a concerted international effort coordinated through InterRIDGE.
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From page 49... ...
The location chosen for this study is the East Pacific Rise south of the Garrett Fracture Zone one of the fastest spreading portions of the mid-ocean ridge system and it is expected that sea-going operations will commence in 1995. One important long-term goal of the RIDGE program is to understand interactions among ridge crest processes on time scales of seconds to decades.
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From page 50... ...
The seafloor mapping and deep submergence technology developed in ridge-related research is already a billion dollar business being widely used in marine-related industries ranging from petroleum exploration to fisheries. BIB' A' Il~-Rccent e~ .~...~.'n'^^'~lee~:~:~::,:::::::::::::::::::::::::::::::::::::::::::::: ,...
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From page 51... ...
Progress has been made in several research areas including obtaining detailed spatial and temporal information of the ridge system and the detection and monitoring of ridge crest phenomena (Box 111. The Global Change and Climate History Program of the U.S.
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From page 52... ...
To improve predictions of future climates, a study is under way to understand the climate history of the eastern North Pacific Ocean and the adjacent land areas of the western United States over the past 130,000 years. A primary objective of the study is to provide detailed correlations of marine and terrestrial climate records along a transect extending from the western interior of the United States to the eastern Pacific Ocean.
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From page 53... ...
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From page 54... ...
and experimentation with climate models, critical environmental feedback mechanisms, such as the role of ocean chemistry and the greenhouse effect, will be better quantified. This will yield improved understanding of global change processes, and better models for predicting future environmental changes on the scale of tens to thousands of years.
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From page 55... ...
To study the response of the ocean to a known, strong, direct forcing (changes in the distribution of solar radiation and atmospheric CO2 content) in order to identify processes that control variability in ocean circulation and chemistry; and to use paleoceanographic histories along with climate models to identify the sensitivity and character (i.e., quasi-linear to nonlinear internal feedbacks)
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From page 56... ...
Through generation and analysis of data and experimentation with climate models, critical environmental feedback mechanisms such as the role of ocean chemistry and the greenhouse effect will be better quantified. This will yield improved understanding of global change processes, and thus better models to predict future environmental changes on the scale of decades to millennia.
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