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Marine Geology Data

World Data Service for Geophysics

More about the role of sea floor sediment in understanding the processes of environmental change.

Thanks to Dr. Alan Mix for the following summary: (1)

"Marine sediments also play a broader role in understanding the processes of environmental change, the key word being processes. Although NOAA's strategic plan elements focus on short-period variability that would seem at first glance to suggest only varved sediments are of interest, study of larger-scale, longer-time, variations in the Earth system are also completely relevant, in the sense that they illuminate processes that may also come into play in all scales of variability. Knowledge of such processes is needed for effective future prediction.

"For example, many predictions of future global warming (such as within the IPCC assessments) don't consider potential dramatic (perhaps even catastrophic) changes in ocean circulation, including the deep sea. The thought that such changes might be important comes from study of the geologic record of the Pleistocene ice ages, which argues that major changes in circulation have indeed occurred in the past.

"Prior to study of the geologic record, the ocean was seen primarily as a source of thermanl inertia, acting to moderate changes. The geologic record suggests the opposite, that the ocean system may be an active player in global climate change -- i.e., it may trigger or amplify changes through it's tendency to shift relatively rapidly into different circulation states, by its role in controlling chemistry of the atmosphere, and through new discoveries -- such as a reservoir of methane hydrates (with both climatic and resource implications)."

(1) Dr. Alan C. Mix, Professor, Associate Dean (interim), College of Oceanic and Atmospheric Sciences, Oregon State University,

Thanks to Dr. Steven Carey for the following:(2)

"Part of the climate change story includes short-term natural excursions that are induced by large scale explosive eruptions. Such global cooling episodes are of the duration of 1-3 years based on historic examples. Deep sea sediments contain a valuable record of explosive volcanism in the form of volcanic ash layers. The study of these layers contributes to the comprehensive study of climate change on relatively short timescales."

(2) Dr. Steven Carey, Graduate School of Oceanography, University of Rhode Island.

Thanks to Dr. Wuchang Wei for the following:(3)

Additional examples illustrating the importance of studying larger-scale, longer-time variations in the Earth system in order to understand and predict climatic short-period variability (one of NOAA's goals).

"Climatic variations in the recent past have been relatively small. For example, during the peak of the last glaciation, atmospheric CO2 concentrations were ~30% less than pre-industrial levels. Anthropogenic release emissions in the last 120 years have increased the pre-industrial level by ~30%. Predicted doubling of the pre-industrial CO2 concentrations for the next hundred years greatly exceed the maximum CO2 concentrations reached during the recent glacial/interglacial cycles. To understand and predict how the earth system will work, it is necessary to investigate how the system worked in the more distant past, such as the early Eocene, late Cretaceous, etc., when the earth was much warmer and CO2 levels were two or more times the pre-industrial values.

"A best example of how the climatic system works in a rapidly increased CO2 and global warming may be the Latest Paleocene Thermal Maximum at ~55 Ma, when the deep sea and high latitude surface water warmed 4-8 degree Celsius within probably a few hundred years or less, CO2 appears to increased at our modern rate, and mass extinction of benthic organism occurred. There is evidence for massive release of methane from methane hydrates in marine sediments at the time that contributed to increased greenhouse gases in the atmosphere. It is very important to find out the detailed causes, mechanism, processes, feedback, and so on, for this event to have a better understanding and prediction of how the climatic system will operate in the future under similar conditions."

(3) Dr. Wuchang Wei, formerly of the Scripps Institution of Oceanography, University of California San Diego.

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