4
Polar Science’s Key Role in Earth System Science

The history of scientific activity in the polar regions is intimately tied to the geopolitical circumstances following World War II and the subsequent Cold War era. In the south, this was dramatically evidenced by the U.S. commitment to the International Geophysical Year (IGY). While polar science, in and of itself, was considered important, it was also an act of U.S. foreign policy to project U.S. global presence and power to serve U.S. interests. As an illustration, the deployment of nearly 3,000 personnel to the McMurdo Sound area in 1957 and 1958 remains the largest presence of U.S. personnel in Antarctica to date. In the north, the advent of the Distant Early Warning (DEW) Line necessitated a year-round presence and created the need for a better understanding of the Arctic environment. The establishment of research facilities in Barrow was an outgrowth of political and military activity of the time. This marriage of science and politics benefited both communities and established a relationship between polar scientists and the military that remains intact today.

With the end of the Cold War and the collapse of the USSR, the political and military rationales for a strong U.S. presence in the polar regions have changed. At the same time, polar science, on its own merits, has assumed a central role in Earth system science. The investments in polar science are extraordinary and reflect the added value placed on a U.S. presence in the polar regions over the years. This is exemplified by the recent agreement to rebuild South Pole Station at a cost of more than $140 million dollars.

The presence of a U.S. territory, Alaska, and U.S. citizens in the Arctic brings significant new emphasis on and importance to science in the north. Historical and projected economic development in the Arctic and the specter of environmental change have added to both its inherent value and the need for polar science, notably in monitoring the effects of climate and providing a predictive capacity for potential future effects. To this end, polar science has grown and matured to a point where it is an important and essential focus of the U.S. research enterprise.

Because science and engineering research in the polar regions is critical to U.S. national interests, its relevance and impact continue to increase. The Arctic and Antarctic provide natural laboratories where extreme environments and geographically unique settings enable research on fundamental phenomena and processes not feasible or possible elsewhere (NSF, 2005). Significant advances in many scientific disciplines and engineering applications have resulted from polar research and many of these discoveries have provided critical knowledge of direct benefit to society (Box 4.1). As global climate has garnered worldwide attention, the polar regions have been found to react acutely to fluctuations in climate and temperature. Since ice tends to reflect solar radiation and water absorbs it, melting in the polar regions can exert a strong influence on both atmospheric climate and ocean circulation. Huge reservoirs of water are held in massive ice sheets and glaciers; substantial release may create major climate and social dislocations. Thus, research in these regions plays a pivotal role in the global Earth system exerting influences of critical importance. The 40 percent reduction in Arctic sea-ice thickness over the past four decades and the collapse of ice shelves in West Antarctica are some of the most dramatic examples of recent changes that have captured the public’s imagination. In many ways, these events have come to represent societal concerns about human influence on Earth’s climate. From a scientific standpoint, evidence continues to accumulate that not only are the polar regions an important focus of research as unique systems, but they also play a pivotal role in global Earth systems.

The execution of polar science faces special challenges due to the harsh environment encountered in conducting experiments, making observations, and collecting samples. A primary characteristic of the polar regions—the presence of ice—while fundamental to the global importance of these regions, presents major logistical challenges. Many locations are difficult to access, and reliable infrastructure must be maintained to safeguard scientists operating safely in these



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Polar Icebreakers in a Changing World: An Assessment of U.S. Needs 4 Polar Science’s Key Role in Earth System Science The history of scientific activity in the polar regions is intimately tied to the geopolitical circumstances following World War II and the subsequent Cold War era. In the south, this was dramatically evidenced by the U.S. commitment to the International Geophysical Year (IGY). While polar science, in and of itself, was considered important, it was also an act of U.S. foreign policy to project U.S. global presence and power to serve U.S. interests. As an illustration, the deployment of nearly 3,000 personnel to the McMurdo Sound area in 1957 and 1958 remains the largest presence of U.S. personnel in Antarctica to date. In the north, the advent of the Distant Early Warning (DEW) Line necessitated a year-round presence and created the need for a better understanding of the Arctic environment. The establishment of research facilities in Barrow was an outgrowth of political and military activity of the time. This marriage of science and politics benefited both communities and established a relationship between polar scientists and the military that remains intact today. With the end of the Cold War and the collapse of the USSR, the political and military rationales for a strong U.S. presence in the polar regions have changed. At the same time, polar science, on its own merits, has assumed a central role in Earth system science. The investments in polar science are extraordinary and reflect the added value placed on a U.S. presence in the polar regions over the years. This is exemplified by the recent agreement to rebuild South Pole Station at a cost of more than $140 million dollars. The presence of a U.S. territory, Alaska, and U.S. citizens in the Arctic brings significant new emphasis on and importance to science in the north. Historical and projected economic development in the Arctic and the specter of environmental change have added to both its inherent value and the need for polar science, notably in monitoring the effects of climate and providing a predictive capacity for potential future effects. To this end, polar science has grown and matured to a point where it is an important and essential focus of the U.S. research enterprise. Because science and engineering research in the polar regions is critical to U.S. national interests, its relevance and impact continue to increase. The Arctic and Antarctic provide natural laboratories where extreme environments and geographically unique settings enable research on fundamental phenomena and processes not feasible or possible elsewhere (NSF, 2005). Significant advances in many scientific disciplines and engineering applications have resulted from polar research and many of these discoveries have provided critical knowledge of direct benefit to society (Box 4.1). As global climate has garnered worldwide attention, the polar regions have been found to react acutely to fluctuations in climate and temperature. Since ice tends to reflect solar radiation and water absorbs it, melting in the polar regions can exert a strong influence on both atmospheric climate and ocean circulation. Huge reservoirs of water are held in massive ice sheets and glaciers; substantial release may create major climate and social dislocations. Thus, research in these regions plays a pivotal role in the global Earth system exerting influences of critical importance. The 40 percent reduction in Arctic sea-ice thickness over the past four decades and the collapse of ice shelves in West Antarctica are some of the most dramatic examples of recent changes that have captured the public’s imagination. In many ways, these events have come to represent societal concerns about human influence on Earth’s climate. From a scientific standpoint, evidence continues to accumulate that not only are the polar regions an important focus of research as unique systems, but they also play a pivotal role in global Earth systems. The execution of polar science faces special challenges due to the harsh environment encountered in conducting experiments, making observations, and collecting samples. A primary characteristic of the polar regions—the presence of ice—while fundamental to the global importance of these regions, presents major logistical challenges. Many locations are difficult to access, and reliable infrastructure must be maintained to safeguard scientists operating safely in these

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Polar Icebreakers in a Changing World: An Assessment of U.S. Needs BOX 4.1 Major Discoveries and Findings from Polar Science The presence and cause of the “ozone hole” The molecular and genetic mechanisms of living systems for coping with freezing conditions The Southern Ocean’s role in driving the deep ocean “conveyor belt” Characterization of climate and effects in both the Arctic and the Antarctic Biological isolation as a fundamental force in the evolution of life A record of past climate changes in ice cores and sedimentary sequences Unique views of our universe and clues to its formation Organic pollutant transport to polar food webs and persistence The slowest spreading center and thinnest oceanic crust on Earth Subglacial environments and hydrological systems beneath ice sheets Paleo outbursts of subglacial waters as a geomorphologic agent of change Meteorological observations critical to weather prediction areas. To this end, a network of stations, field camps, laboratory facilities, ships, airplanes, observing networks, and other support infrastructure has been developed over the years in both the Arctic and the Antarctic. Essential to these operations is access through and operation ice-covered oceans and coastal seas. The support of polar research requires ships of various icebreaking capabilities, including those that are the subject of this report. This chapter highlights some of the major research themes being pursued in polar science, demonstrating the value provided by this work to the nation. A glimpse of where this science will go in the future is also provided. The scientific value justifies the significant investment needed for polar research to continue and indeed flourish over the next several decades. Simply put, access to the polar regions is fundamentally important if the United States is to continue to be a leader in polar science. Icebreakers are a key part of the necessary infrastructure: They are needed to conduct science in Arctic waters and to open a channel to allow resupply of McMurdo Station (and, in turn, South Pole Station and inland sites) in Antarctica. ARCTIC SCIENCE The Arctic Ocean is surrounded by land, with much of the terrain and adjacent shorelines difficult to reach because of ice and challenging weather conditions. Routes to coastal areas are from the south; there are few roads, rail lines, or airports, and there are few or no infrastructure or support facilities along the coast. The conduct of science on land and in coastal areas tends to be based at a few sparsely distributed, remote outposts. In many cases, ships are the most reliable means of access. To date, research that uses icebreakers has focused either on ocean or coastal processes, although icebreakers may be employed to bring sophisticated science assets to remote Arctic terrestrial localities. For example, the Swedish icebreaker ODEN was used to deliver scientific equipment and personnel to remote terrestrial sites in the Arctic during the Swedish “Beringia 2005” expedition. The Coast Guard icebreaker HEALY routinely supports biological, sea ice, marine geological and geophysical, oceanographic, and atmospheric studies. Life in the Arctic Arctic biological research addresses basic questions about the role of the Arctic in the global carbon cycle, arctic biodiversity, and adaptations of living systems to cold environments. A multiyear study of biological production and transport of carbon from the Bering and Chukchi Sea shelves to the ocean basin north of Alaska has been conducted from icebreakers. Shelf-basin transport is relatively poorly understood and is hypothesized to play a significant role in the global carbon system. Arctic Basin biodiversity is being studied as part of the Exploration of the Seas and the Census of Marine Life programs. Other programs are studying the ability of polar organisms to avoid freezing and to withstand the formation of ice in their body fluids. Animals in the Arctic do not freeze to death when their core body temperature falls as low as 2°C but return to a metabolically active state when the body’s heat-generating mechanisms are activated. Many polar insects and plants attain even lower cell temperatures, yet their cells remain ice-free because of antifreeze compounds in their biological fluids (NRC, 2004). Some polar animals and plants experience ice formation in extracellular fluids and yet appear to be undamaged. The knowledge gained from studies of the mechanisms that regulate freezing of extracellular water and protect against damage from ice formation will continue to advance our knowledge of cryotechnologies and biomedicine. An already important application is improvement in methods for low-temperature storage of biological materials, ranging from isolated cells to intact organisms (NRC, 2004). Understanding mechanisms of freezing resistance has broad technological applications in agricultural science (e.g., design of freeze-resistant crops) and biomedicine (e.g., development of improved cryopreservation techniques) (NRC, 2004). Geology and Geophysics Exploration of the Gakkel Ridge is shedding light on how new ocean crust is formed and tectonic plates are

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Polar Icebreakers in a Changing World: An Assessment of U.S. Needs spreading apart in the central Arctic Basin. The studies being conducted at the Gakkel Ridge can be accomplished only with the use of an icebreaker. Data gathered in HEALY’s 2001 cruise already have confirmed that Gakkel Ridge is the slowest spreading mid-ocean ridge on Earth. The oceanic crust at this location is also the thinnest yet observed. Cleary, the tectonic history of the Arctic Basin is key to understanding past ocean circulation and climate, and very little information is available. Exploration of the Arctic ocean floor will clarify the geological history of the polar regions and allow reconstruction of Arctic tectonics, notably providing information on how it has influenced ocean circulation (NRC, 2004). A return to the Gakkel Ridge area will address this knowledge gap. The international Law of the Sea Treaty enables countries to lay claim to ocean bottom and subbottom areas for economic activities, but requires that these claims be based on seafloor configuration and seaward extensions of terrestrial land features. This is determined through the examination of ocean bottom topography, generally using multibeam sonar profiling. The Arctic Basin is one of the most poorly understood basins for seafloor topography. Icebreaker cruises in the north routinely collect multibeam sonar data, and specific expeditions have been conducted to establish bottom topography in areas critical to potential claims under the Law of the Sea. Given that other countries are making aggressive claims in the Arctic Ocean, these data are important to substantiate U.S. claims. To collect the data needed, a ship with multibeam sonar equipment able to break ice at a reasonable speed is critical. Also, the use of towed seismic arrays for sub-seafloor imaging will be increasingly important in the future and have a role in Law of the Sea territorial claims. Our ability to describe the variability, change, and extremes of the polar region environment is limited by a lack of observations in both space and time. Records of past environmental conditions, retrieved from paleoarchives such as ice cores or sediments, provide clues to nature’s response to forcing, but these too are incomplete, especially in terms of spatial coverage (NRC, 2004). For example, the Arctic Basin appears to play a critical role in the global carbon balance; however the mechanism by which this carbon is transported from the Arctic continental shelf to the deep basin is poorly understood. Significant changes appear to be occurring in the balance between waters of Pacific and Atlantic origin, and this may threaten key features of the thermohaline profile (heat and salt balance) that are thought to prevent much of the surface ice from melting. The tectonic history of ocean gateways, which allow passage of warm or cold currents between oceans, is useful for understanding climate in both Arctic and Antarctic regions. For example, Fram Strait, between Svalbard and Greenland, is the only deep-water gateway between the Arctic Basin and the global oceans, and the date of its formation is unknown (NRC, 2004). Similarly, constraints on the opening history of Australia-Antarctica and South America-Antarctica gateways will allow better understanding of the onset of the Antarctic Circumpolar Current and its effects on climate and biological evolution (NRC, 2004). Atmospheric Science Atmospheric processes in the Arctic, such as the formation and persistence of clouds, the transport and disposition of solar radiation, and large-scale patterns of variability in the atmospheric pressure fields, play a central role in global climate. A more detailed understanding and representation of these processes in global climate models is essential to improving predictions of future climate (ACIA, 2005). Such advances in understanding require intensive observations of the Arctic atmosphere over the oceans, which depend strongly on icebreaker support, for the deployment of drifting ice camps, transects with icebreakers across the Arctic Ocean, and deployment of measurement systems (e.g., Perovich et al., 2003). Oceanography The Arctic Basin remains to be sampled properly from the standpoint of understanding its physics and chemistry. There is a need to increase physical exploration of the Arctic Ocean Basin. To date studies have focused on the quantifying deep circum-Arctic circulation. Biological studies of shelf basins and examination of the flux of material out of the Arctic through the Canadian Archipelago have to be done. This work is conducted by submarines or supported by aircraft, both of which have severe limitations on payload, thus limiting the kinds of data that can be obtained. An icebreaker provides the ideal platform necessary for this work because of its laboratories and capacity to carry large, multidisciplinary science teams. Sea Ice Research on the physics, chemistry, and biology of oceanic sea ice is dependent on the availability of icebreakers, submarines, and/or sea-ice camps. Access from submarines for the civilian research community is no longer available, and sea-ice camps are infrequently deployed. Icebreakers are the most effective platform for these studies. Because sea ice provides the interface between atmosphere and water, it is one of the most important components of the system. While some work can be done near shore on coastal ice or using specialized aircraft for excursions into the ocean environment, the wide geographic coverage made possible by icebreakers is an important factor. Human Disturbances of the Environment The discovery of “Arctic haze” in the 1970s and early 1980s (Barrie, 1992) demonstrated that the Arctic no longer

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Polar Icebreakers in a Changing World: An Assessment of U.S. Needs is a pristine environment isolated from human activity, if it ever was. The Arctic is connected to global sources of natural and anthropogenic chemicals via winds, ice movement, and marine currents (NRC, 2004). The study of this phenomenon led to the discovery of ozone depletion in the troposphere and in the Arctic marine boundary layer at polar sunrise (Oltmans, 1981; Bottenheim et al., 1986). In the mid-1980s the depletion of Antarctic ozone was measured. It was established that industrially produced chlorofluorocarbons were the dominant cause of the ozone hole. Discovery of the relationship between chlorofluorocarbons and ozone loss sparked international policy makers to adopt the Montreal Protocol to phase out these chemicals. By the end of the 1990s, global production of these compounds had decreased by more than 90 percent. ANTARCTIC SCIENCE In contrast to the Arctic, Antarctica is a continent surrounded by oceans. The continent has been mostly entombed in a thick ice cover for millennia, creating a unique setting for research. Research in the Antarctic and the Southern Ocean addresses a wide array of topics across many disciplines. Antarctic research requires access throughout the Southern Ocean as well as the continent, both of which depend on capable and reliable icebreakers and ice-strengthened ships. Ongoing research falls into five major areas: biology and medicine, geology and geophysics, ocean and climate systems, aeronomy and astrophysics, and glaciology. The following discussion provides examples of research in Antarctica, but the list is not exhaustive. Biology and Medicine Antarctic biological research focuses on three broad themes: (1) adaptation of organisms to the extremes of temperature and seasonality; (2) the characteristics, structure, and functions of marine and terrestrial ecosystems; and (3) responses of organisms and ecosystems to global change. Research over the last few decades has shown that there is significant biodiversity in both the marine and the terrestrial environments. Much of this diversity arises from unique functional adaptations that allow organisms to survive and thrive in Antarctica. The current scientific frontier in the discipline is the application of modern methods of molecular biology to gain an understanding of the genetic basis for these important adaptations. Study of genes associated with cold tolerance and freeze avoidance in fish provides insights into the evolution and adaptation of organisms in extreme environments. This research has already resulted in the discovery of new compounds and molecules useful to society and most certainly will continue to do so. The Southern Ocean marine environment is one of the most biologically productive regions in the world. This ecosystem has fewer trophic pathways than do tropical marine systems, making it easier to study both its components and its entirety. It also is characterized by extensive seasonal variations in light and the extent of sea ice that exert different pressures on seemingly similar organisms. For instance, some penguin species thrive in regions of widespread and persistent sea ice, yet others need more open-water conditions. As a result, changes in sea ice in the Antarctic Peninsula that may be associated with global change cause shifts in breeding areas and, thereby, reproductive success for some penguin species. Thus, research on the native marine mammals of the Antarctic Peninsula is an important contribution to understanding the physiological and genetic functions of these mammals and the potential effects of changing climate on this unique ecosystem. Weddell seals that live in the Antarctic dive to great depths in search of food and consequently sustain long periods without breathing. Research on these seals has provided fundamental knowledge of how mammals, including humans, handle gas dissolved in blood during and after deep diving events and has even contributed to advances in understanding sudden infant death syndrome (SIDS). The Antarctic terrestrial environment supports a sparse but hardy biota. Work at the Dry Valleys Long Term Ecological Research (LTER) site, a “cold desert” member of the LTER network, is elucidating how seemingly depauperate systems respond to both short-term events and longer-term global change. Researchers at the recently established Microbial Observatory in the McMurdo Dry Valleys employ molecular, genetic, and genomic methods to understand the fundamental basis for microbial adaptation to the harsh conditions. The results of these studies contribute significantly to our understanding of the role microorganisms play in global systems ecology. Geology and Geophysics Antarctic research in this area includes paleontology, which reveals the history of life as it evolved in Antarctica— including the presence of dinosaurs and large marine reptiles—and studies of the Earth’s deep interior through seismic observations that are not possible anywhere else in the world. Research is also aimed at the recovery and interpretation of sediment records from continental margin regions. Sediments provide information about changing conditions in the oceans over geological time. These sediment records complement ice core records, forming a powerful approach to studying the changing Earth. ANDRILL is an international collaboration of the United States, Italy, Germany, and New Zealand to recover and study sediment cores that span important intervals of time as the Earth transitioned from a greenhouse world to an icehouse world. These records will reveal the history of ice sheet development on the continent and go beyond the proxy records of general ice mass that have been inferred from deep ocean sediments. Another area of research is the remote study of the subglacial lithosphere

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Polar Icebreakers in a Changing World: An Assessment of U.S. Needs via remote sensing—often using airborne sensors. These studies have revealed important characteristics of the sub-ice materials such as the presence of sediments versus hard rock, geological structures, and potential areas of high heat flow that are key to fully modeling ice sheet dynamics. The land beneath the ice sheets of Antarctica remains poorly understood and largely unexplored, yet knowledge of the geological and hydrological characteristics of these subglacial regions is vital for understanding ice sheet development. The nature of the underlying bedrock is a crucial boundary condition that defines the stability of the ice sheet to climatic changes (NRC, 2004). Major regions of Antarctica that are crucial to deciphering the intertwined geodynamic-limatic history puzzle remain to be explored for the first time. For example, the Gamburtsev Mountains in East Antarctica cover an immense region the size of Texas, yet detailed topography and peak elevation of the mountains remain matters of conjecture. Climate models suggest that the high elevation of these mountains was crucial in localizing the first Cenozoic ice sheets that formed 34 million years ago. This onset of glaciation affected the entire Earth, as global climate changed from the hothouse world of the early Cenozoic to the more recent world in which whole continents are covered in ice. Recent discoveries show that beneath several miles of Antarctic ice, there are subglacial lakes that range in size from Lake Vostok, a body the size of Lake Ontario, to small marshy accumulations of a few kilometers’ dimension. More than 145 lakes have been identified (Siegert et al., 2005), suggesting that the subglacial environments may be interconnected hydrological systems (Wingham et al., 2006). The extent and degree of interconnection among the lakes are unknown. These recently discovered subglacial environments formed in response to the complex interplay of tectonics and topography with climate and ice sheet flow over millions of years. The temperatures and pressures of subglacial lakes are similar to the environment of the deep oceans. However, subglacial environments are unique planetary-scale mesocosms found nowhere else on Earth. Sealed from the atmosphere for many millions of years, subglacial environments are the closest Earth-bound analogues to the icy domains of Mars and Europa (Siegert et al., 2001). These environments will be a target of intense study over the next decade or more. The potential for being able to study microorganisms of prehistoric origin is extraordinary, allowing a lens to be focused on the early history of life on this planet. Ocean and Climate Systems Antarctic research in this area includes both oceanography and lower-atmospheric studies. Oceanographers study the formation and distribution of cold-water masses that affect global circulation in the oceans. Processes of production and flow of Antarctic bottom water are tied to the annual formation of sea ice and circumpolar circulation. Southern Ocean circumpolar currents, the largest of the ocean’s currents, combine with air mass and heat exchange in the atmosphere to affect climate on regional and global scales. In addition, atmospheric and oceanic research is trying to better understand ice sheet behavior. Researchers are determining the effect of ocean circulation (including melting) on ice shelves. This component of ice sheet behavior may determine when ice shelves form and when coalescing icebergs are thick enough floating glaciers to buttress ice streams. Without ice shelves, inland ice moves faster and thinning of the ice sheet occurs. Loss of ice is balanced by new snow on the ice sheet. At the heart of climate, its variability and change derives from meteorology and atmospheric sciences, significant aspects of which can be studied effectively from icebreakers. Changes in polar regions are tightly coupled to global earth systems, with changes in one strongly impacting the other. Evidence of abrupt climate changes was found in the analysis of ice cores from the Greenland Ice Sheet Project (GISP 2). Pronounced changes in climate were found to occur (see, e.g., NRC, 2002) on a time scale of a few years and to extend for centuries. Antarctic Vostok ice cores provide a spectacular record of changes in temperature and atmospheric gas concentration over the last four glacial-interglacial cycles—400,000 years. The International Trans-Antarctic Scientific Expedition (ITASE) is collecting detailed records at a large number of sites in Antarctica. These records span the last several hundred years and offer information about changes in climate during the transition from low to high anthropogenic greenhouse gas production. Research is also under way to understand how precipitation has changed over time and how recent precipitation patterns relate to global phenomena such as El Niño and La Niña events. The Climate Monitoring and Diagnostics Laboratory at South Pole Station is one of four National Oceanic and Atmospheric Administration (NOAA) atmospheric baseline observatories that monitor atmospheric gases, aerosol particles, solar radiation, the Earth’s atmospheric system controlling climate forcing, ozone depletion, and baseline air. These observations produce long-term records used to improve global and regional environmental information and services. Large unmanned helium balloons are launched routinely from sites throughout Antarctica. These balloons provide the National Aeronautics and Space Administration (NASA) with an inexpensive means to place payloads into a space environment. The unique capabilities of this program are crucial for the development of new technologies and payloads for NASA’s space flight missions. Many important scientific observations in fields such as hard x-ray/gamma-ray and infrared astronomy, cosmic rays, and atmospheric studies have been made from balloons. McMurdo Station is one of the ground stations for the National Polar-orbiting Operational Environmental Satellite System (NPOESS). Polar-orbiting satellites observe Earth

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Polar Icebreakers in a Changing World: An Assessment of U.S. Needs from space and collect and disseminate data on Earth’s weather, atmosphere, oceans, land, and near-space environment. Ground stations provide connectivity for the system of satellites to enable monitoring of the entire planet and provide data for long-range weather and climate forecasts, which increases the timeliness and accuracy of severe weather event forecasts. Operational environmental data from polar-orbiting satellites are important to the achievement of U.S. economic, national security, scientific, and foreign policy goals. For NPOESS to collect and disseminate data for the entire planet, all ground stations must be operational. McMurdo Station is the southernmost ground station and provides critical data to NPOESS. Without support from the McMurdo ground station, data transfer may be interrupted and hinder long-range weather and climate forecasts. While many significant scientific discoveries have come from exploration and scientific investigations of the polar regions, many of the large-scale environmental changes witnessed in the polar regions within the past few decades involve poorly understood linked regional and global processes. In many areas the changes and their causes are only partly perceived because the polar regions are not completely “mapped,” and exploration of such elements as the seafloor, the ice sheet bed, the crustal domain, and the biota is still needed to understand fully the nature and cause of past changes (NRC, 2004). Glaciology Antarctic research in glaciology focuses on studies of climate variation through ice cores and studies of the ice sheet to understand how they work and how this might change in the future. Earth’s climate has changed dramatically over geological time. More recent changes can be studied by extracting both direct and proxy records from snow and ice cores. These records are used to understand how the Antarctic has responded to, and how it has been a forcing factor in, climate over the last 500,000 years. Over the next several years, a deep ice core will be drilled in central West Antarctica (the WAISCORES Project) to produce records of climate and atmospheric gases over the last 120,000 years, not only to understand change in Antarctica but also for comparison with a similar record from central Greenland, thus gaining understanding of interhemispheric variations. Substantial research is also being done to understand the dynamics of the ice sheets—how they change and how fast they can change. Achieving reliable prognostic models for ice sheet behavior is important because of the large effect that changes in the ice sheet have on global sea level. Recent work in this field was conducted in collaboration with the British Antarctic Survey. A joint aerogeophysical survey of the Thwaites-Pine Island Glacier drainage was conducted to gather important boundary conditions, such as ice thickness, sub-ice bed elevation, and nature of the bed, for ice sheet models. Research is aimed at understanding the effects of ocean tides on ice shelves and ice streams far into the interior of the ice sheets. Aeronomy and Astrophysics Antarctic research in this area covers a spectrum of activities including solar-terrestrial interactions and the Earth’s magnetosphere, as well as astronomy and astrophysics. The observations made at stations and remote sites are essential to understanding solar processes. Much remains to be learned about the Sun and the interactions of its highly variable photon, plasma, and particle emissions, which are the key “upper” boundary conditions to processes at work in the polar regions. A better understanding of the Sun and solar variability is necessary to understand how natural variations affect polar phenomena and human existence (NRC, 2004). Magnetic field lines stretching out from the polar regions interact with the flowing and variable solar wind, transferring electromagnetic and charged particle energy to the upper atmosphere of the polar caps. The portions of such energies that may be responsible for such important polar phenomena as, for example, noctilucent clouds are completely unknown today (NRC, 2004). Variabilities in the emission of solar photons over all wavelengths—the so-called solar constant—affect the polar regions and global climate in ways that are only beginning to be studied through models and simulations. Global cloud cover data, including in the polar regions, which are important for models and which can be affected by solar emissions and their variability, are almost absent from databases of the polar environment. Except for the past 10 years or so, actual solar variability data needed for models have been taken largely by proxy from studies of polar and glacial ice sheets, ocean sediments, and other terrestrial sources (NRC, 2004). The polar regions are uniquely suited to studies of interaction of the solar wind and the Earth because particles and energy from these interactions travel along Earth’s magnetic field to Earth’s surface in the polar regions, where they can be measured. South Pole Station, being located high on the interior ice plateau, is the best site in the world for certain kinds of astronomy because of the low sky temperature, ultralow moisture content, and long periods suitable for observations. These conditions facilitate discoveries that are not possible elsewhere in the world. Information about the early history of our solar system is enhanced through the collection of Antarctic meteorites made available to scientists around the United States and the world. Although rare, several samples of the Moon and Mars have been discovered and have provided important information about how these celestial bodies formed. Radio astronomy has proven very successful, particularly with regard to studying the cosmic microwave background radiation, left over from the Big Bang, which offers important clues to the origin of the universe. In addition, the clear ice found deep beneath South Pole Station has proven

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Polar Icebreakers in a Changing World: An Assessment of U.S. Needs to be an excellent site for a new kind of observatory, one designed to study high-energy neutrinos that provide information about phenomena such as supernovae in the universe. Neutrinos are abundant in the universe but interact with other matter very infrequently. Consequently, a very large detector is needed. Under construction at South Pole Station is the first and largest high-energy neutrino observatory in the world. When completed, it will consist of a cubic kilometer of ice that has been instrumented with nearly 5,000 detectors to find these elusive particles and determine their source in the universe. THE INTERNATIONAL POLAR YEAR 2007-2008 Another consideration in thinking about the future use of icebreakers is the upcoming International Polar Year (IPY) 2007-2008 and its legacies. IPY will be an intense, coordinated field campaign of polar observations, research, and analysis that will be multidisciplinary in scope and international in participation. More than 35 nations are committed to participate. IPY 2007-2008 will provide a framework to undertake projects that normally could not be achieved by any single nation. It permits thinking beyond traditional borders—whether national borders or disciplinary constraints—toward a new level of integrated, cooperative science. Its coordinated international approach maximizes both impact and cost-effectiveness, and the international collaborations started today will build relationships and understanding that will bring long-term benefits. Within this context, IPY will seek to galvanize new and innovative observations and research while at the same time building on and enhancing existing relevant initiatives. IPY will serve as a mechanism to attract and develop a new generation of scientists and engineers with the versatility to tackle complex global issues. In addition, IPY is clearly an opportunity to organize an exciting range of education and outreach activities designed to excite and engage the public, with a presence in classrooms around the world and in the media in varied and innovative formats. The IPY will use today’s powerful research tools to better understand the key roles of the polar regions in global processes. Automatic observatories, satellite-based remote sensing, autonomous vehicles, the Internet and other modern communications tools, and genomics are just a few of the innovative approaches to help us study previously inaccessible realms. IPY 2007-2008 will be fundamentally broader than past international scientific years because it will explicitly incorporate multidisciplinary and interdisciplinary studies, including biological, ecological, and social science elements. Continued exploration and scientific study of the polar regions will lead to answers to important scientific questions and provide unexpected discoveries. New logistical capabilities and recently developed technologies will further augment the major breakthroughs in scientific understanding of the extreme environments that have been accomplished to date (NRC, 2006). Because large portions of the Arctic and Antarctic are accessible only by ship, realization of this potential for new insights and advances in polar research will depend heavily on ships capable of operating in ice-covered regions, either as research platforms or as key components of the logistics chain supporting on-continent research in the Arctic and the Antarctic (NSF, 2005). FINAL THOUGHTS This chapter has highlighted some of the most exciting polar research being conducted today. Polar research is contributing to a wide range of disciplines, providing fundamental information about Earth’s systems and how they operate. The continued vitality of polar research is intimately linked to the availability of the appropriate infrastructure and logistical support to allow scientists to work in these challenging environments. Conducting research in the polar regions is as complex and challenging as space science. Like research in outer space, U.S. leadership in international polar science is being challenged as countries increasingly exercise their national prerogatives at the poles. As polar science advances, more and more difficult scientific questions are being asked that will require sustained and continuous observations and measurements in these regions. In the north, access to the central Arctic Basin will provide an understanding of the evolution of northern climates. Prediction of future change can be based only on a full understanding of the Arctic and Antarctic systems. In the south, year-round scientific access will be vital, with current research limited by the ability of researchers and teams to access on a regular basis all of the ice-covered seas of Antarctica and the Arctic. While assets and platforms such as airplanes and spaceborne sensors are important technological tools for future investigations, surface ground-truth and in situ sampling cannot and will not be replaced in the foreseeable future. The availability of adequate icebreaking capabilities is fundamental and essential to research in the polar regions of our planet, from which we gain an understanding of human life on Earth, both historically and climatically. The committee noted the successful relationship between U.S. Coast Guard HEALY operations and the U.S. Arctic marine science community, fostered in part by the UNOLS (University-National Oceanographic Laboratory System) Arctic Icebreaker Coordinating Committee (AICC) and supports the continuation of this successful relationship.

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