DE-FE0010180

Goal
The goal of this research is to assess the contemporary state of the upper continental slope in the Alaskan Beaufort Sea to determine if gas hydrates are in equilibrium with present-day climate conditions.

Performers
Southern Methodist University ? Dallas, TX
Oregon State University ? Corvallis, OR
US Geological Survey ? Woods Hole, MA

Background
The gas hydrate stability zone thins or vanishes on upper continental slopes (~250 to 500 m water depth) worldwide due to prevailing pressure-temperature conditions. An estimated 3.5 percent of the global gas hydrate inventory is contained in thin zones in the near-seafloor sediments of these upper continental slopes. This gas hydrate accumulation is the most susceptible on Earth to dissociation as a result of contemporary climate change. The time lag between climate events (e.g., sea level fluctuations, water temperature variations) and the re-equilibration of gas hydrates in the upper continental slope areas in the Arctic also means that some of these zones may still be readjusting to climate change since the end of the last glacial maximum (~20 ka).

Schematic of Earth?s permafrost-associated and deepwater gas hydrate provinces. Focus of this research is on the most climate-susceptible gas hydrates, located within the yellow box.

Impact
This project will?through an assessment of the impact of climate change on susceptible gas hydrates in the U.S. Arctic?yield the first systematic geochemical and microbiological data to constrain subseafloor methane sinks and the spatio-temporal changes in the nature of microbial systems and pore fluids in re-equilibrating gas hydrate zones. The project will be the first ever to directly acquire thermal data from the Beaufort Sea continental slope and represents an integration of physical (oceanography, geophysics), chemical, and biological science. The project will yield constraints on the rate of re-equilibration of gas hydrates located on the upper continental slope in response to external forcings as well as quantitative predictions about the impact of hydrate-derived gas on the strength of slope sediments (geohazards), the flux of gas to the overlying ocean, and the areal extent of dissociation (or, in some cases, hydrate re-formation) processes.

Accomplishments
The USGS has completed processing of multi-component seismic data collected from the Beaufort Sea in recent years (see USGS DE-FE0002911 for more information).

SMU has constrained the upper and lower boundary conditions in their methane hydrate stability model. Upper boundary conditions were based on an analysis of depth-dependent ocean temperatures over various time periods. Lower boundary conditions consider heat flow across the North Slope and Beaufort Sea, and were based on a rigorous statistical analysis of offshore seismic data and historical conductivity and temperature logs. The result is a first-of-its-kind land-sea heat flow contour map of the North Slope of Alaska to the abyssal plane of the Beaufort Sea.

Current Status (June 2013)
SMU is integrating heat flow and ocean temperature (e.g., the boundary conditions) into the numerical model to predict the location of all observed bottom-seismic reflections. The current model is a steady-state model which can provide insights into the methane hydrate system under stable conditions. One goal of the project will be to develop a dynamic heat flow model that can predict how changes in temperature will affect hydrate stability. The project team is working to achieve this forward model by forcing changes in ocean temperatures and through the addition of latent heat effects from hydrates during dissociation.

The USGS is progressing with their scoping exercise of the R/V Norseman II. This is the preferred research vessel identified for the 2014 coring and heat flow expedition. USGS scientists and coring operations staff plan to visit Seattle to meet with the crew and operator of the ship while it remains in drydock undergoing major modifications, which will benefit the 2014 expedition.

Project Start: October 1, 2012
Project End: September 30, 2015

Project Cost Information:
Phase 1 - DOE Contribution: $102,337, Performer Contribution: $59,641
Phase 2 - DOE Contribution: $615,082, Performer Contribution: $93,475
Phase 3 - DOE Contribution: $244,298, Performer Contribution: $96,998
Planned Total Funding:
DOE Contribution: $961,717, Performer Contribution: $250,114

Contact Information:
NETL ? Robert Vagnetti (Robert.Vagnetti@netl.doe.gov or 304-285-1334)
Southern Methodist University ? Dr. Matthew Hornbach (mhornbach@smu.edu or 214-768-2389)
Oregon State University ? Prof. Frederick Colwell (rcolwell@coas.oregonstate.edu or 541-737-5220)
USGS ? Dr. Carolyn Ruppel (cruppel@usgs.gov or 508-457-2339)
USGS ? Dr. John Pohlman (jpohlman@usgs.gov or 508-457-2213)

Additional Information

Research Performance Progress Report [PDF-108KB] January - March, 2013

Research Performance Progress Report [PDF-425KB] October - December, 2012