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Research for Fisheries Management

NOAA is the primary federal agency responsible for understanding and predicting climate changes, and their impact on Earth environments and resources. As stated in the NOAA Strategic Plan for 2003-2008, this includes "understanding of past climate variations and atmospheric, oceanic, and land-surface processes that influence climate." The oceans are by far the largest repository of carbon on the planet, and play a crucial role in the atmospheric inventory of greenhouse gases, in particular carbon dioxide and methane. Most of the global carbon is sequestered in deep sea sediments. However, seafloor seeps and vents also contribute both heat and carbon to the oceans and atmosphere. They are also "hot spots" for biodiversity and life in the ocean. Listed below are examples of NURP seep and vent research that has changed fundamental understanding of life on earth and the impacts the oceans have on global climate:

Management Objective - Understanding Past Climate Variations
Most of the past 14,000 years is offshore from current sea level. Analyses of ancient shorelines and the modern processes that affect the geologic record in rocks, ancient reefs, and shells (taphonomy) provide a basis for understanding current and predicting future climate changes.

Ancient Shorelines - Global temperature rise since the last glacial stage 14,000 years ago has been as rapid as any time in recorded history. Over the past 1.5 million years there have been many rapid transitions from glacial to interglacial stages. All this history is accessible on the continental shelf. Along the Gulf of Mexico and southeast coast, carbonate ledges outcrop all across the shelf. These formed during various low-sea level stands. The first step was to date the ancient shoreline rocks. Most of the surficial rocks are recent limestone formed by attached animals such as corals and coralline algae. Reaching the original rock base requires diver-operated cores. By using divers, core sites can be precisely located in the target features, e.g., more vertical surfaces with less biotic cover, something that could not be done by lowering corers from a surface vessel. Based on these analyses, researchers reconstructed the approximate speed of past sea level changes and environmental conditions such as temperature at the time of formation. For more information….

Management Objective - Describe Ocean Processes that Influence Climate & the Carbon Cycle
Seafloor vents and seeps are significant sources of heat and materials to the oceans. Undersea technologies are required to explore, visit, and measure the rates and impacts of emissions from these features, which range in size from a bubble streams to undersea volcanoes.

Gas Hydrate Outcrops in the Gulf of Mexico - Only in the 1990s have scientists begun to realize the extent of gas hydrates beneath the sea. Gas hydrates are ice crystal cages that form around a molecule of natural gas, mostly methane, the most potent greenhouse gas in the atmosphere and second only in concentration to carbon dioxide. One cubic foot of hydrate ice holds 160 cubic feet of natural gas! Hold a match to it, and the ice will burn away. Current estimates indicate that there is ten times more carbon in gas hydrates then all other fossil fuels in the world combined. They occur off every shoreline from the tropics to the poles. Thus, oil and gas companies around the world are now exploring the possibility of mining gas from the ice. The disadvantage however is that, due to the volatile nature of the reservoir, mining is hazardous. Oil companies try to steer around known beds with pipelines and platforms for fear that the bottom will melt away from under their structures. In the early 1990s NURP dives discovered gas hydrate beds outcropping at the seafloor in the northern Gulf of Mexico. More recently, studies suggest that massive meltdowns of seafloor hydrates may have caused regional to global climate change, e.g., 5°C rise over a 1000 years. Since these discoveries, the outcrops have served as natural laboratories to better understand their stability and surrounding conditions. Custom equipment has measured the rate of dissociation in relation to minor changes (1°C) in bottom water temperature. In 1997, scientists discovered a news species of iceworm living in hydrates, likely grazing off other microbial life that appears to thrive in this extreme environment. For more information….

 

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Updated: July 30, 2004