Bibliography - Arctic

This analysis presents a conservation planning framework for decisions under uncertainty and applies it to the Arctic Coastal Plain of Alaska. Uncertainty arises from variable distributional shifts of species' ranges due to climate change. The planning framework consists of a two-stage optimization model that selects a nominal conservation area network in the first stage and evaluates its performance under the climate scenarios in the second stage. The model is applied to eleven at-risk species in Alaska including the threatened Spectacled Eider and Steller's Eider sea ducks and the polar bear. The 109th United States Congress and 2008 federal budget proposed opening for oil and gas development the "1002 Area" of the Arctic National Wildlife Refuge, which intersects the Plain. This analysis finds that, if Arctic Alaska experiences 1.5 _C of warming by 2040 (as predicted by the Intergovernmental Panel on Climate Change's A2 scenario), then potential habitat will decrease significantly for eight of these at-risk species, including the polar bear. This analysis also shows that there is synergism between oil and gas development and climate change. For instance, climate change accompanied by no development of the 1002 Area results in an increase of potential habitat for Steller's Eider. However, if development accompanies climate change, then there is a 20% decrease in that area. Further, this analysis quantifies the tradeoff between development and maintenance of suitable habitat for at-risk species.

The Arctic climate is changing. Permafrost is warming, hydrological processes are changing and biological and social systems are also evolving in response to these changing conditions. Knowing how the structure and function of arctic terrestrial ecosystems are responding to recent and persistent climate change is paramount to understanding the future state of the Earth system and how humans will need to adapt. Our holistic review presents a broad array of evidence that illustrates convincingly; the Arctic is undergoing a system-wide response to an altered climatic state. New extreme and seasonal surface climatic conditions are being experienced, a range of biophysical states and processes influenced by the threshold and phase change of freezing point are being altered, hydrological and biogeochemical cycles are shifting, and more regularly human sub-systems are being affected. Importantly, the patterns, magnitude and mechanisms of change have sometimes been unpredictable or difficult to isolate due to compounding factors. In almost every discipline represented, we show how the biocomplexity of the Arctic system has highlighted and challenged a paucity of integrated scientific knowledge, the lack of sustained observational and experimental time series, and the technical and logistic constraints of researching the Arctic environment. This study supports ongoing efforts to strengthen the interdisciplinarity of arctic system science and improve the coupling of large scale experimental manipulation with sustained time series observations by incorporating and integrating novel technologies, remote sensing and modeling.

We review seven Arctic and four subarctic marine mammal species, their habitat requirements, and evidence for biological and demographic responses to climate change. We then describe a pan-Arctic quantitative index of species sensitivity to climate change based on population size, geographic range, habitat specificity, diet diversity, migration, site fidelity, sensitivity to changes in sea ice, sensitivity to changes in the trophic web, and maximum population growth potential (Rmax). The index suggests three types of sensitivity based on: (1) narrowness of distribution and specialization in feeding, (2) seasonal dependence on ice, and (3) reliance on sea ice as a structure for access to prey and predator avoidance. Based on the index, the hooded seal, the polar bear, and the narwhal appear to be the three most sensitive Arctic marine mammal species, primarily due to reliance on sea ice and specialized feeding. The least sensitive species were the ringed seal and bearded seal, primarily due to large circumpolar distributions, large population sizes, and flexible habitat requirements. The index provides an objective framework for ranking species and focusing future research on the effects of climate change on Arctic marine mammals. Finally, we distinguish between highly sensitive species and good indicator species and discuss regional variation and species-specific ecology that confounds Arctic-wide generalization regarding the effects of climate change.

Projected shifts in climate forcing variables such as temperature and precipitation are of great relevance to arctic freshwater ecosystems and biota. These will result in many direct and indirect effects upon the ecosystems and fish present therein. Shifts projected for fish populations will range from positive to negative in overall effect, differ among species and also among populations within species depending upon their biology and tolerances, and will be integrated by the fish within their local aquascapes. This results in a wide range of future possibilities for arctic freshwater and diadromous fishes. Owing to a dearth of basic knowledge regarding fish biology and habitat interactions in the north, complicated by scaling issues and uncertainty in future climate projections, only qualitative scenarios can be developed in most cases. This limits preparedness to meet challenges of climate change in the Arctic with respect to fish and fisheries.

The unprecedented depletion of sea ice in large sectors of the Arctic Ocean in the summer of 2007 has been the subject of many publications which highlight the spectacular disappearance of the sea ice at the time of minimum ice cover or emphasise the losses at very high latitudes. However, minimum values can be strongly affected by specific circumstances occurring in a comparatively short time interval. The unusually clear skies and the presence of a particular wind pattern over the Arctic Ocean may partly explain the record minimum attained in September 2007. In this contribution, instead of limiting ourselves to the September minimum or the March maximum, we consider the ice conditions throughout the year, opting for a less used, and hopefully more convenient approach. We chose as variables to describe the evolution of the sea ice situation in the Arctic Ocean and peripheral seas in the 1979-2007 period the length of the ice- free season (LIFS) and the inverse sea ice index (ISII). The latter is a quantity that measures the degree of absence of sea ice in a year and varies between zero (when there is a perennial ice cover) and one (when there is open water all year round). We used sea ice concentration data obtained from passive microwave satellite imagery and processed with the Bootstrap algorithm for the SMMR and SSM/I periods, and with the Enhanced NASA Team algorithm for the AMSR-E period. From a linear fit of the observed data, we found that the average LIFS in the Arctic went from 118 days in the late 1970s to 148 days in 2006, which represents an average rate of increase of 1.1 days/year. In the period 2001-2007 the LIFS increased monotonically at an average rate of 5.5 days/year, in good agreement with the general consensus that the Arctic sea ice is currently in an accelerated decline. We also found that 2007 was the longest ice- free season on record (168 days). The ISII also reached a maximum in 2007 . We also investigated what happened at the regional level. For example, the Northwest Passage and the Northern Sea Route are especially relevant to assess the maritime transport between the Atlantic and the Pacific, changes in the ice cover in oil rich areas such as the north coast of Alaska will attract the attention of the oil industry, and the disappearance of the sea ice in Hudson Bay will strongly affect its wildlife. We divided the Arctic in 85 regions and examined how the LIFS and the ISII changed in each of them since 1979. 53 regions enjoyed their longest ice-free seasons in 2006 or 2007. 2006 was special for the Canadian Arctic (longest ice-free season on record for about half of the regions) while 2007 was the year of the Russian Arctic (with the longest ice-free season in the period under study for more than half of the regions). Some of the largest variations were observed in the Russian Arctic, where the average LIFS increased from 84 days in the late 1970s to 129 around 2006, to reach a maximum of 171 days in 2007. Let us quote the changes in the White Sea (105 days between 1979 and 2006), in the South Barents Sea (70 days), in the South East Siberian Sea (60 days) and in the mid-latitude Chukchi Sea (66 days). Other areas where important changes took place include the Gulf of Finland (101 days), the Gulf of Riga (111 days) and the West coast of Spitsbergen (61 days). In the Canadian Arctic it is worth mentioning the increase of 62 days in Hudson Strait, 36 days in Hudson and Baffin Bays, and 52 days in Davis St. In almost all straits and sounds of the High Canadian Arctic the increase has been clearly non-linear and we prefer to compare the average LIFS in the periods 1979-1983 and 2002-2006. We quote an increase of 87 days in Lancaster Sound and of 74 days in Coronation Gulf.

Recent analyses have revealed trends over the past 20-30 years of decreasing sea ice extent in the Arctic Ocean coincident with warming trends. Such trends may be indicative of the polar amplification of warming predicted for the next several decades in response to increasing atmospheric CO2. We have summarized these predictions and nonuniform patterns of arctic climate change in order to address their potential effects on marine mammals. Since recent trends in sea ice extent are nonuniform, the direct and indirect effects on marine mammals are expected to vary geographically. Changes in the extent and concentration of sea ice may alter the seasonal distributions, geographic ranges, patterns of migration, nutritional status, reproductive success, and ultimately the abundance and stock structure of some species. Ice-associated seals, which rely on suitable ice substrate for resting, pupping, and molting, may be especially vulnerable to such changes. As recent decreases in ice coverage have been more extensive in the Siberian Arctic (60°E-180°E) than in the Beaufort Sea and western sectors, we speculate that marine mammal populations in the Siberian Arctic may be among the first to experience climate-induced geographic shifts or altered reproductive capacity due to persistent changes in ice extent. Alteration in the extent and productivity of ice-edge systems may affect the density and distribution of important ice-associated prey of marine mammals, such as arctic cod Boreogadus saida and sympagic ("with ice") amphipods. Present climate models, however, are insufficient to predict regional ice dynamics, winds, mesoscale features, and mechanisms of nutrient resupply, which must be known to predict productivity and trophic response. Therefore, it is critical that mesoscale process-oriented studies identify the biophysical coupling required to maintain suitable prey availability and ice-associated habitat for marine mammals on regional arctic scales. Only an integrated ecosystems approach can address the complexity of factors determining productivity and cascading trophic dynamics in a warmer Arctic. This approach, integrated with monitoring of key indicator species (e.g., bowhead whale, ringed seal, and beluga), should be a high priority.