January 2013 Issue
USGS Science in the Changing Arctic
Director, U.S. Geological Survey
To most people, issues concerning the Arctic can seem remote and disconnected from their daily lives. But I assure you nothing could be further from the truth as our actions affect the remote Arctic, and future changes in the Arctic increasingly impact our quality of life.
For that reason, the U.S. Geological Survey (USGS) is providing scientific information to guide sound decisions on environment and mineral and energy resources for this important part of the planet. The sheer magnitude of the challenge of research in a frontier area like the Arctic has driven the USGS to adopt the most efficient data collection strategies, creative partnerships and novel technologies.
Mapping the Seafloor
Over the past five years, more than 15,000 kilometers of multichannel seismic reflection data have been gathered beneath ice-covered portions of the Arctic between Alaska and the North Pole. These data are rewriting the geologic history of this remote and poorly understood ocean basin. The expeditions have been a collaborative effort involving the USGS, Geological Survey of Canada, NOAA, the U.S. Department of State and the U.S. Coast Guard using the Coast Guard’s icebreaker cutter Healy.
The interpretation of seismic reflection data and associated dredge samples will be used to understand the outer limits of the region beyond today’s exclusive economic zone, where the U.S. may have sovereign rights over seafloor and subseafloor energy, mineral and sedentary biological resources. The U.S. and Canadian ships alternated duties, with one ship breaking ice while the other followed behind to collect data through the freshly cut channel.
The USGS and its partners approached Arctic Ocean data collection in a novel way that exemplifies true collaboration in an area with challenging conditions.
Arctic Ocean Acidification
USGS scientists seized the opportunity to join these cruises, funded primarily for the purposes of exploring the extended continental shelf, and conducted other experiments on board Healy. Auxiliary sampling efforts included water and ice to improve understanding of ocean acidification in the coastal Bering Sea shelf and the Arctic Ocean.
During cruises from 2010 to 2012, the USGS collected more than 34,000 measurements of water chemistry data using underway flow-through sampling. Samples were taken from a continuous flow-water system and analyzed using a Multiparameter Inorganic Carbon Analyzer, developed by the University of South Florida’s College of Marine Science, every two to seven minutes for pH, partial pressure of carbon dioxide in the water and dissolved inorganic carbon.
Discrete surface water samples were also collected every hour and immediately analyzed for pH and alkalinity or carbonate ion concentration. Additional discrete surface water samples were taken approximately every one to four hours for total alkalinity, total carbon, inorganic nutrients, stable carbon and oxygen isotopic composition, elemental analysis, dissolved organic carbon, and particulate organic carbon for later laboratory analysis.
These data—one of the highest resolution and comprehensive data sets—are then used to calculate saturation state of the water, which is a reflection of whether carbonate minerals (i.e., corals and shells on organisms such as oysters, crabs and shrimp) will dissolve, thereby providing information on habitat changes from ocean acidification.
The USGS Gas Hydrate Project is expanding the use of existing technologies to assess Arctic energy resources and the impact of climate change on Arctic methane emissions. Globally, gas hydrates sequester huge amounts of methane that may eventually prove an important energy source, particularly for nations that lack access to domestic hydrocarbons.
In collaboration with the Georgia Institute of Technology, the USGS is refining the Instrumented Pressure Testing Chamber (IPTC), which measures the geophysical and strength properties of hydrate-bearing sediments that are recovered through coring procedures designed to preserve the samples’ reservoir pressure and prevent gas hydrate destabilization. Using the IPTC to monitor the volume of gas produced when samples are depressurized under controlled conditions is important for assessing the potential for commercial production of natural gas from methane hydrates in Arctic and deepwater marine settings.
The USGS has also worked with Texas A&M University to add a seawater equilibrator to an off-the-shelf cavity ringdown spectrometer capable of measuring methane and carbon dioxide concentrations in near-surface waters several times per second while a research ship is underway. The spectrometer uses a nondestructive laser to analyze gas concentrations, providing faster and more accurate measurements than conventional techniques. The real-time data permit scientists to directly determine the rate of methane loss across the ocean-atmosphere interface and to identify marine hot spots for greenhouse gas emissions, particularly on rapidly warming Arctic Ocean margins.
Measuring Shoreline Change With Lidar
High-resolution airborne lidar elevation data have been acquired for approximately 1,600 kilometers of the north coast of Alaska through a jointly funded effort by the USGS, U.S. Bureau of Land Management and U.S. Fish and Wildlife Service. The data will be used to evaluate shoreline change and analyze existing and future landscape and habitat change associated with inundation, coastal erosion and deposition, the stability of lakes, drainage patterns and other hydrologic features.
The data coverage includes the barrier islands and mainland coast of Alaska between Icy Cape and the U.S.-Canadian border, from the shoreline to 1.5 kilometers inland. Data coverage has doubled to around 3 kilometers on the Barrow Peninsula and along the coast of Teshekpuk Lake, where coastal erosion rates are amongst the highest in the world at more than 18 meters per year.
The U.S., the state of Alaska, tribal governments and coastal communities will have elevation data for making decisions about how to maintain natural resources and sustain human activities.
An Oceangoing Community
While the Arctic may not be a large area of the globe, it is a region where many science missions of the USGS coalesce to address current and future challenges that resource managers and policymakers face in being responsible stewards. The stakes are high, and so are the costs of working in such a challenging environment.
For that reason, I am constantly amazed at the creativity of USGS scientists in finding efficient ways to get the job done. I am also thankful for the entire oceangoing community that has offered an extra berth, new tools and space for equipment to ensure scientists can maximize data collection.
Together, we will continue to advance understanding of our ever-changing and dynamic planet for the health and benefit of people and ecosystems.