How has climate warming in the Arctic affected parasites and vectors among land mammals? What impact has this had on the health of muskoxen and other Arctic land mammals? Do these changes have broader implications for Arctic ecosystems? How has climate warming affected polar bears and other Arctic marine mammals? What are the broader ecological implications of these changes? How has climate warming affected Arctic and sub-Arctic forests and their resistance to pests, for example? What are the implications of these and other changes for the future?
Dr. Anthony Socci, Senior Science Fellow, American Meteorological Society
Dr. Susan Kutz, Associate Professor of Wildlife and Ecosystem Health, Faculty of Veterinary Medicine, University of Calgary, Alberta Canada
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Dr. Glenn Patrick Juday, Professor of Forest Ecology and Director of the Tree-Ring Laboratory, School of Natural Resources and Agricultural Sciences, University of Alaska, Fairbanks AK
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Dr. Steven C. Amstrup, Research Wildlife Biologist, United States Geological Survey at the Alaska Science Center, Anchorage AK
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The Impacts of Climate Change on Arctic Land Mammals:
The Role of Parasites and Hosts
Global climate change is altering the ecology of infectious agents and driving the emergence of disease in people, domestic animals, and wildlife. At northern latitudes, where climate change is occurring most rapidly, the implications may be severe. Northern species, including parasites and their vectors, have evolved under severe environmental constraints, and a warmer, wetter climate may release them from these constraints with profound implications. For example, the transmission cycle of an important lung nematode, Umingmakstrongylus pallikuukensis, in muskoxen has shifted from a predominantly two-year to a one-year cycle over the last 30 years. It is anticipated that this will lead to increased occurrence of lungworm in muskoxen and an expanded geographic range of the parasite.
Increased levels of infection and expansion of the geographic range of parasites in the Arctic is a concern because many parasites, including the muskox lungworm, the sheep muscle worm, the various stomach worms of ungulates, and other pathogens, have very subtle, yet profound impacts on the survival and reproductive success of their hosts.. Healthy and sustainable wildlife populations are tremendously important for the maintenance of the cultural, economic, and physical well-being of Arctic and Subarctic peoples and for the integrity of northern ecosystems. Small changes in the Arctic climate may have a profound influence on the occurrence and patterns of infectious diseases in northern wildlife species, and ultimately the health of northern peoples and ecosystems. Further studies defining the diversity and distribution of northern pathogens, the patterns of transmission, and the impacts on wildlife and people are essential to prepare for the ecosystem level impacts of climate change at northern latitudes. Additionally, the Arctic can serve as the ‘canary in the coalmine’ where detecting, understanding, and predicting the responses of high latitude host-parasite systems can provide considerable insight into implications of warming on a global scale.
Climate Change Has Strongly Affected the Forests of Alaska
The climate of Alaska has warmed in specific ways that have strongly affected the growth and health of its forests. Over the past century in central Alaska the growing season is 50% to 100% longer, daily low temperatures are nearly 3 degrees C warmer during the growing season while daily highs are little changed, and winters are 5 to 7 degrees C warmer. The total area burned in wildland fires is directly related to total number and consecutive duration of warmest (27 degrees C) summer days at Fairbanks. The summer of 2004 at Fairbanks recorded the highest mean temperature in the 101-year weather record, resulting in 6.7 million acres burned, the greatest in the 56-year fire record. Summer 2005 was also hot and dry, resulting in 4.6 million acres burned. In the northeast quadrant of Alaska the 2-year total burned area represents about one third of all forest land. The total area burned in Alaska and adjacent Yukon Territory in 2 years was about 16 million acres, equivalent to the area of Ireland.
Temperature directly controls the year-to-year change in tree growth on perhaps the majority of sites in Alaska. At treeline in the Alaska Range and Brooks Range Mountains, about 40% of white spruce grow best when the previous July temperature is low and least when July temperature is high. About 38% of treeline white spruce in grow best when March or April mean temperatures are highest, specifically above freezing. In central Alaska white spruce on commercially productive sites grew at about half the rate during the warmth of the past 3 decades compared to the cooler early and middle 20th century. Paper birch and black spruce growth on many sites in central Alaska is also least in warm years, although a few populations experience increased growth in warm years. Growth of Alaska trees that are sensitive to climate can now be calibrated to temperature, and forecast for given temperature scenarios. Temperature scenarios used in the Arctic Climate Impact Assessment, should they actually occur, would result in widespread death of existing tree populations. Alaska's most valuable timber species, Alaska yellow cedar, has experienced widespread death of mature trees across about 750K acres during the past century. New results strongly implicate premature loss of freeze tolerance from warmer winters as the cause of yellow cedar decline. Spruce bark beetles have killed most mature white spruce on 4.5 million acres in south central Alaska, the largest single tree-killing insect outbreak in U.S. history. Warm winters and warm summers promote bark beetle outbreaks, and "super" outbreak weather conditions have prevailed in recent years. Spruce budworm requires early summer warmth to reproduce or reach outbreak levels and was generally absent in central Alaska until 1990. Spruce budworm populations reached damaging outbreak levels in 2006 on the most productive commercial forest sites.
Impact of Arctic Warming on Polar Bear Populations
Polar bears are tied to the sea ice for nearly all of their life cycle functions. Most important of these is foraging, or access to food. Polar bears almost exclusively eat seals, and they are equally as dependent upon the sea for their nutrition as are seals, whales, and other aquatic mammals. Polar bears are not aquatic, however, and their only access to the seals, upon which they depend, is from the surface of the sea ice. Over the past 25 years, the summer sea ice melt period has lengthened, and summer sea ice cover has declined by over half a million square miles. In winter, although sea ice extent has not changed as greatly, there have been dramatic reductions in the amount of old ice, predominantly in the western Arctic. This loss of stable old ice has set up additional losses of sea ice cover each summer because the thinner younger ice is more easily melted during the recent warmer summers.
Dr. Susan Kutz is an Associate Professor of Wildlife and Ecosystem Health at the newly established Faculty of Veterinary Medicine, University of Calgary, Canada. Dr. Kutz’s research focuses on understanding the biodiversity, impacts, and response to climate change of pathogens in Arctic and Subarctic wildlife and the pathogen-related interactions between people and wildlife and wildlife and domestic animals. Related to this research, she is developing community-based programs for long term monitoring and early detection of changes in the health of remote wildlife populations. She is co-founder of a successful program for outreach, education, and community-based monitoring of wildlife health in the Northwest Territories (http://wildlife1.usask.ca/Sahtu/).
Dr. Kutz has recently been awarded a three-year grant from Alberta Ingenuity for her research “Impacts of climate change on the biodiversity, epidemiology, and impacts of parasites in caribou” and another three year grant NSERC International Polar Year to investigate “Resilience of Caribou and Reindeer Populations: Validation and Application of the Filter Paper Technique to Assess Exposure to Pathogens during International Polar Year(s)”. Dr. Kutz has published 22 peer reviewed journal articles, 2 book chapters, delivered over 15 invited papers and 50 additional presentations at national and international meetings on her research on Arctic and Subarctic wildlife parasites and diseases. She has also produced several technical reports and provided numerous educational seminars and workshops on the health of Arctic and Subarctic wildlife.
Dr. Glenn Patrick Juday is Professor of Forest Ecology and Director of the Tree-Ring Laboratory in the School of Natural Resources and Agricultural Sciences at the University of Alaska Fairbanks, where he has worked since 1981. He was formerly Research Ecologist with the USDA Forest Service 1978-1981. He received his B.S. summa cum laude, in 1972 in Forest Management from Purdue University, and his Ph.D. in 1976, in Plant Ecology from Oregon State University. He completed a Rockefeller Foundation Post-Doctoral Fellowship in Environmental Affairs, 1976-1977 serving as Executive Chair of the Oregon Natural Area Preserves Advisory Commission. He spent a sabbatical in the headquarters of The Nature Conservancy in Arlington Virginia in 1988.
Dr Juday is currently a Co-Principal Investigator in the NSF-supported Bonanza Creek Long-Term Ecological Research site in central Alaska. His research specialties include climate change, tree-ring studies, biodiversity and forest management, and forest development following fire. He is the Lead author of the chapter on Forests and Agriculture of the Arctic Climate Impact Assessment, and a contributing author to the chapter on Biodiversity Conservation. Dr. Juday has served as science advisor for several television programs on climate warming, including the PBS series Scientific American Frontiers. His research results were discussed in 2 issues of National Geographic magazine in 2004. He has also briefed and led trips for several member of Congress. Dr. Juday was recognized for outstanding accomplishments as Chairman of Forest Ecology Working Group of the Society of American Foresters in 2000. He is the author of over 30 scientific peer-reviewed journal articles and book chapters including Nature, Climatic Change, Global Change Biology, Forest Ecology and Management and Canadian Journal of Forest Research. He has book chapters published by Oxford University Press, Cambridge University Press, and Annual Review of Ecology and Systematics. He is currently contributing to the 4th Global Environment Outlook (GEO 4), chapters on Polar Regions.
Steven C. Amstrup is a Research Wildlife Biologist with the United States Geological Survey at the Alaska Science Center, Anchorage AK. He holds a B.S. in Forestry from the University of Washington (1972), a M.S. in Wildlife Management from the University of Idaho (1975), and a Ph.D. in Wildlife Management from the University of Alaska Fairbanks (1995). He has been conducting research on all aspects of polar bear ecology in the Beaufort Sea for 25 years. His research interests include distribution and movement patterns aswell as population dynamics of wildlife, and how information on those topics can be used to assure wise stewardship. He is particularly interested in how science can help to reconcile the ever enlarging human footprint on our environment with the needs of other species for that same environment. Prior work experiences include studies of black bears in central Idaho, and pronghorns and grouse in Wyoming. On their honeymoon in New Zealand, Steven and his wife Virginia helped in a tagging study of little blue penguins. That experience gave Steve the honor of being one of the very few people ever to have been bitten by both polar bears and penguins. Steven has authored or coauthored over 50 peer reviewed articles on movements, distribution and population dynamics of large mammals, and is the senior editor of a recent text on population estimation methods.
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