17 Ergebnisse.

Observable changes with regional and global implications, such as warming temperatures and reduced sea ice, are taking place across the Arctic. However, the record of Arctic observations suffers from incomplete geographic coverage and limited duration, and measurements are not well coordinated. This makes it difficult to comprehensively describe current conditions in the Arctic, let alone understand the changes that are underway or their conne...

For an unknown reason, the Steller sea lion population in Alaska has declined by 80% over the past three decades. In 2001, the National Research Council began a study to assess the many hypotheses proposed to explain the sea lion decline including insufficient food due to fishing or the late 1970s climate/regime shift, a disease epidemic, pollution, illegal shooting, subsistence harvest, and predation by killer whales or sharks. The report's a...

The high latitudes of the Arctic and Antarctic, together with some mountainous areas with glaciers and long-lasting snow, are sometimes called the cryosphere-defined as that portion of the planet where water is perennially or seasonally frozen as sea ice, snow cover, permafrost, ice sheets, and glaciers. Variations in the extent and characteristics of surface ice and snow in the high latitudes are of fundamental importance to global climate be...

International Polar Year 2007-2008 (IPY) was an intense, coordinated field campaign of observations, research, and analysis. It was the largest, most comprehensive campaign ever mounted to explore Earth's polar domains. Legacies and Lessons of the International Polar Year 2007-2008 summarizes how IPY engaged the public to communicate the relevance of polar research to the entire planet, strengthened connections with the Indigenous people of th...

Based on recommendations from a 2004 National Academies report, the AYK Sustainable Salmon Initiative (SSI) developed a research and restoration plan. This report reviews the draft plan, recommending some clarification, shortening, and other improvements, with a focus on the relationship between the intellectual model and the research questions.

The International Polar Year (IPY) 2007-2008 will be an internationally coordinated campaign of polar observations, research, and analysis that will further our understanding of physical and social processes in the polar regions, examine their globally-connected role in the climate system, and establish research infrastructure for the future. Within this context, the IPY will galvanize new and innovative observations and research while at the ...

During the 1990s, a government program brought together environmental scientists and members of the intelligence community to consider how classified assets and data could be applied to further the understanding of environmental change. As part of the Medea program, collection of overhead classified imagery of sea ice at four sites around the Arctic basin was initiated in 1999, and two additional sites were added in 2005. Collection of images ...

Recent well documented reductions in the thickness and extent of Arctic sea ice cover, which can be linked to the warming climate, are affecting the global climate system and are also affecting the global economic system as marine access to the Arctic region and natural resource development increase. Satellite data show that during each of the past six summers, sea ice cover has shrunk to its smallest in three decades. The composition of the i...

Antarctica is renowned for its extreme cold, yet surprisingly, radar measurements have revealed a vast network of lakes, rivers, and streams several kilometers beneath the Antarctic ice sheet. Sealed from Earth's atmosphere for millions of years, they may provide vital information about microbial evolution, the past climate of the Antarctic, and the formation of ice sheets, among other things. The next stage of exploration requires direct samp...

The climate record for the past 100, 000 years clearly indicates that the climate system has undergone periodic--and often extreme--shifts, sometimes in as little as a decade or less. The causes of abrupt climate changes have not been clearly established, but the triggering of events is likely to be the result of multiple natural processes. Abrupt climate changes of the magnitude seen in the past would have far-reaching implications for human ...

This book reviews the performance and effectiveness of the Community Development Quotas (CDQ) programs created as a result of the Sustainable Fisheries Act of 1996. The CDQ program is a method of allocating access to fisheries to eligible communities with the intent of promoting local social and economic conditions through participation in fishing-related activities.The book looks at those Alaskan fisheries experienced with such CDQs for halib...

The polar regions are experiencing rapid changes in climate. These changes are causing observable ecological impacts of various types and degrees of severity at all ecosystem levels, including society. Even larger changes and more significant impacts are anticipated. As species respond to changing environments over time, their interactions with the physical world and other organisms can also change. This chain of interactions can trigger casca...

Once ice-bound, difficult to access, and largely ignored by the rest of the world, the Arctic is now front and center in the midst of many important questions facing the world today. Our daily weather, what we eat, and coastal flooding are all interconnected with the future of the Arctic. The year 2012 was an astounding year for Arctic change. The summer sea ice volume smashed previous records, losing approximately 75 percent of its value sinc...

This project was supported by Contract No. IHP-03-093 between the National Academy of Sciences and the Alaska Department of Fish and Game"--T.p. verso.

Permafrost is a thermal condition -- its formation, persistence and disappearance are highly dependent on climate. General circulation models predict that, for a doubling of atmospheric concentrations of carbon dioxide, mean annual air temperatures may rise up to several degrees over much of the Arctic. In the discontinuous permafrost region, where ground temperatures are within 1-2 degrees of thawing, permafrost will likely ultimately disappe...

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This book identifies accumulated environmental, social and economic effects of oil and gas leasing, exploration, and production on Alaska's North Slope. Economic benefits to the region have been accompanied by effects of the roads, infrastructure and activities of oil and gas production on the terrain, plants, animals and peoples of the North Slope. While attempts by the oil industry and regulatory agencies have reduced many of the environment...