Below are the first 10 and last 10 pages of uncorrected machine-read text (when available) of this chapter, followed by the top 30 algorithmically extracted key phrases from the chapter as a whole.
Intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text on the opening pages of each chapter. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.
Do not use for reproduction, copying, pasting, or reading; exclusively for search engines.
OCR for page 1
Summary The loss of Arctic sea ice observed in recent years and the possibility that the Arctic Basin may become seasonally ice-free raise a number of environmental, economic, and national security issues. Sea ice is an important resource for coastal communities and ecosystems as a platform and a habitat, but it can also be a hazard for industrial activity. With increased periods of open water, industrial development and shipping are likely to increase to unprecedented levels. Destinational and trans-arctic shipping between the industrial centers of the Atlantic and Pacific will expand. Exploitation of natural resources will become more feasible as the ice recedes from continental shelves in summer. The Arctic will enter a new regime requiring international agreements and environmental regulation, with new policies for territorial waters, economic zones, search and rescue, and environmental protection. To prepare for managing the transition to an Arctic that is nearly ice free in the summer, it is critical to have accurate projections of Arctic environmental changes over the next several decades. Forecasts of regional sea-ice conditions on seasonal timescales can help different stakeholders prepare for and adapt to the impacts of climate change and minimize environmental risks associated with development. Although the Intergovernmental Panel on Climate Change (IPCC) models provide meaningful projections of future global temperature and precipitation, projections of Arctic sea ice cover range widely, from almost no change to the end of the 21st century to a disappearance of the ice cover at the end of summer 20 years from now. In part, the models are hampered by the fact that many of the physical processes occurring in summer are poorly understood due to a lack of observations at appropriate times and scales. It is difficult and expensive to maintain manned drifting stations on the ice and conduct observational flights. In the history of U.S. Arctic research, there have been only four all-summer drifting stations. The spring melt and fall freeze-up periods are particularly challenging due to the rapidly changing environmental conditions and the weak platform offered by thin ice. This report addresses a unique dataset that could facilitate significant advances in the scientific understanding of Arctic sea ice as we seek to address the myriad issues discussed above. During the 1990s, the Medea program brought together environmental scientists and members of the intelligence community to apply classified assets and data to further the understanding of environmental change. Under Medea auspices, the global “fiducials” program was established whereby participating scientists could request collection of classified images at environmentally sensitive locations around the globe. The term “fiducials” refers to the fact that the classified images were to be kept “in trust” in classified archives, with the eventual goal of declassification and release to the broader scientific community for research purposes. In 1999, Medea scientists requested that the intelligence community begin collecting images of Arctic sea ice at four different locations in the Arctic Basin during the summer months (the melt season). Two additional locations were added in 2005. Collection of images during the summer months at these six sites has continued until the present day. 1
OCR for page 1
2 Scientific Value of Arctic Sea Ice Imagery Derived Products In the latter years of the Medea program, procedures were established whereby Literal Imagery Derived Products (LIDPs) could be produced from the classified fiducials data at a resolution deemed suitable for declassification. Several hundred unclassified LIDPs with a nominal resolution of 1 meter have been produced from the images collected at the 6 Arctic sites. These images are unclassified but are not yet released to the public. These images, when released, could lend themselves to a wide range of studies leading to significant improvements in the way in which sea ice physical processes are represented in climate models, as well as understanding changes in ice habitat (Box S-1). Moreover, these data, which are derived from the unique capabilities provided by the classified imagery systems, provide a unique opportunity for scientists to leverage existing and publicly available data provided by unclassified civil and commercial satellite systems to maximum scientific benefit. RECOMMENDATIONS Recommendation: The Intelligence Community should release and disseminate all Arctic sea ice LIDPs that have been produced to date as soon as possible. The Committee sees great value in releasing these sea ice images to the general public and scientific community. They provide information at scales, locations, and time periods that are extraordinarily important in advancing our knowledge of critical processes during this era of rapid loss and transformation of Arctic sea ice. There are no other data available that show the melting and freezing processes that we were able to observe in these images; their release will have a major impact on understanding effects of climate change on sea ice and ice habitat. All of the Arctic sea ice LIDPs contain information that will be extremely valuable to scientific research. Three categories of LIDPs are of particularly high priority for dissemination and publicity efforts: (1) all six sites during 2007-2008, (2) all from the Barrow site, and (3) all from the Beaufort Sea site (Box S-2). Recommendation: To maximize the utility of the images, the committee recommends that the metadata include: thumbnail (smaller size) copies of the images, exact information on the location of the images, calibration information, the time of acquisition, and information on the pointing angle. The committee understands that the trustees of the fiducials archive, the U.S. Geological Survey’s Civil Applications Program, are preparing a website to disseminate the derived Arctic sea-ice images. Inclusion of these metadata in the online archive would greatly facilitate the research of scientists who obtain and use the images.
OCR for page 1
Summary 3 BOX S-1 Processes Better Understood through the Medea Literal Imagery Derived Products (LIDPs) Snow Depth: In the absence of any other method to observe the snow cover, the Medea data will provide valuable information about its morphology and interaction with the surface topography and will help to improve the interpretation of Ice, Clouds, Land Elevation Satellite (ICESat) laser altimeter records (a civilian data source) in terms of freeboard, ice thickness, and snow depth. Lateral Melting: Sequential one-meter resolution images will enable scientists both to measure the kinematic shifts of ice floe assemblies and track the surface area of each individual piece of ice. Such observations are likely to help explain the contribution of lateral melting to the loss of multiyear ice. Ice Topography and Albedo: There are virtually no sustained, systematic observations of the evolution of the spatial variability in ice albedo because neither radar nor passive microwave images have sufficient resolution. The LIDPs will provide an unprecedented view of how the surface topography affects the initial formation and subsequent evolution of melt ponds and their effect on the albedo and hence the short- wave radiative energy balance. Calibration information would make the images even more useful for albedo. Ice Thickness Evolution: The designers of sea-ice models have no choice but to parameterize a relationship between albedo and ice thickness, which makes it a powerful tuning parameter. Ice thickness distributions from ICESat and albedo derived from Medea surface characterizations should be invaluable to improve these parameterizations. Deformation: If it were possible to compare the 10-km ice velocity and deformation field with the high-resolution view of the Medea data, we could expect new insight on the relationship of stress and strain rate at the larger scales. Shear and Crack Patterns: The 1-meter resolution Medea data would be of significant benefit to our understanding of ice failure and deformation processes as well as to calculations of the mass balance of the ice cover. Melt Pond Recurrence: The ability to follow an individual piece of ice from freeze-up throughout the winter until the onset of melting in the following summer would shed light not only on the recurrence of melt ponds but also the seasonal evolution of albedo. Habitat: The Medea data should significantly increase our ability to understand and track patterns that govern the evolution of mammal habitats, including polar bears, and the distribution of fisheries.
OCR for page 1
4 Scientific Value of Arctic Sea Ice Imagery Derived Products BOX S-2 Priorities for Dissemination and Publicity Efforts All 2007-2008 Data: This window coincides with the International Polar Year (IPY). Images from all six sites during this time will greatly enhance the benefits and value of a broad range of intensive ground-based observations that were collected during the IPY. Furthermore, this subset includes images of the minimum in sea-ice coverage observed during the summer 2007, when the extent of summer melt far exceeded the previous record. Barrow: Images from the Barrow site would support a range of high-profile research projects in the coastal region at Barrow (Norton, 2001). These data will serve as an important resource for questions revolving around adaptation of coastal communities and ecosystems to climate change. Beaufort Sea: The Beaufort Sea, with imagery dating to 1999, exhibits the broadest range of different ice types and ice ages, greatly increasing the value of Arctic sea-ice LIDPs in improving our ability to monitor and forecast the movement and evolution of different ice age and thickness classes. Forecasts of regional sea-ice conditions on seasonal timescales can help different stakeholders prepare for and adapt to the impacts of climate change and minimize environmental risks associated with industrial activity. Converging economic activities (natural resource extraction and shipping) and indigenous interests (subsistence harvest of marine mammals) in the Beaufort region place great importance on the detection and tracking of multiyear ice. Offshore oil and gas exploration activities in this region will also benefit from more accurate determination of the ice edge and hazardous ice conditions. CONSIDERATIONS FOR THE FUTURE If data will be collected in the future and LIDPs produced for the purpose of public release, some modifications/additions would make the data even more useful for scientific research. Operators of classified assets could continue to collect ice images during suitable atmospheric conditions at the existing Beaufort Sea, Canada Basin, and Chukchi Sea sites. Assuming that the location and number of sites is not fixed, adding collection of imagery at the North Pole, where extended field observations are already underway, would be particularly valuable. Dynamic image collection that tracks how an individual ice feature evolves over time and a mechanism to communicate this information in near real-time for a given feature would complement the existing data, which are images at fixed locations in space through which different ice features pass over time. If available, any corresponding radar data would be particularly valuable.