Analysis of a 60 km segment of the Alaskan Beaufort Sea coast using a time‐series of aerial photography revealed that mean annual erosion rates increased from 6.8 m a−1 (1955 to 1979), to 8.7 m a−1 (1979 to 2002), to 13.6 m a−1 (2002 to 2007). We also observed that spatial patterns of erosion have become more uniform across shoreline types with different degrees of ice‐richness. Further, during the remainder of the 2007 ice‐free season 25 m of erosion occurred locally, in the absence of a westerly storm event. Concurrent arctic changes potentially responsible for this shift in the rate and pattern of land loss include declining sea ice extent, increasing summertime sea surface temperature, rising sea‐level, and increases in storm power and corresponding wave action. Taken together, these factors may be leading to a new regime of ocean‐land interactions that are repositioning and reshaping the Arctic coastline.
Modeling studies examining the effect of lakes on regional and global climate, as well as studies on the influence of climate variability and change on aquatic ecosystems, are surveyed. Fully coupled atmosphere-land surface-lake climate models that could be used for both of these types of study simultaneously do not presently exist, though there are many applications that would benefit from such models. It is argued here that current understanding of physical and biogeochemical processes in freshwater systems is sufficient to begin to construct such models, and a path forward is proposed. The largest impediment to fully representing lakes in the climate system lies in the handling of lakes that are too small to be explicitly resolved by the climate model, and that make up the majority of the lake-covered area at the resolutions currently used by global and regional climate models. Ongoing development within the hydrological sciences community and continual improvements in model resolution should help ameliorate this issue.It has been long understood that lakes and reservoirs can influence local and regional climate, as open water has significantly different radiative and thermal properties compared with soil or vegetated surfaces. It is not surprising then, that various attempts have been made over the years to include the effects of terrestrial surface water in global and regional climate modeling studies, though the effects considered are usually limited to the flux exchange of moisture, heat, and momentum with the overlying atmosphere. On the other hand, the effect of climate variability and change on thermal structure, water quality, and aquatic ecosystems-also long known to be important-is generally only evaluated in the context of individual lakes or reservoirs. Even though very elaborate models exist for examining these issues, they are generally not run fully coupled with global or regional climate models, presumably because of the computational expense or the complexity of such an exercise (or both). Yet to understand the role of lakes and reservoirs in the climate system, fully coupled models must be developed in which key lacustrine processes relevant on climate timescales are integrated within the climate model. This is especially clear given the recent (and growing) awareness of the importance of lakes and reservoirs in the global carbon balance (St. Louis et al. 2000;Tranvik et al. 2009;Williamson et al. 2009). Nutrient loading, biogeochemical cycling, food webs, and ecosystems will all need to be represented, in addition to the thermal structure, mixing regimes, and ice cover that are usually considered in climate modeling studies (i.e., if lakes and reservoirs are considered at all). Modeling techniques exist for all of these, yet it would appear that a fully coupled atmosphere-land surface-lake model that would meet the needs of both the terrestrial
People in the Arctic face uncertainty in their daily lives as they contend with environmental changes at a range of scales from local to global. Freshwater is a critical resource to people, and although water resource indicators have been developed that operate from regional to global scales and for midlatitude to equatorial environments, no appropriate index exists for assessing the vulnerability of Arctic communities to changing water resources at the local scale. The Arctic Water Resource Vulnerability Index (AWRVI) is proposed as a tool that Arctic communities can use to assess their relative vulnerability-resilience to changes in their water resources from a variety of biophysical and socioeconomic processes. The AWRVI is based on a social-ecological systems perspective that includes physical and social indicators of change and is demonstrated in three case study communities/watersheds in Alaska. These results highlight the value of communities engaging in the process of using the AWRVI and the diagnostic capability of examining the suite of constituent physical and social scores rather than the total AWRVI score alone.
Arp, C.D., B.M. Jones, M. Whitman, A. Larsen, and F.E. Urban, 2010. Lake Temperature and Ice Cover Regimes in the Alaskan Subarctic and Arctic: Integrated Monitoring, Remote Sensing, and Modeling. Journal of the American Water Resources Association (JAWRA) 46(4): 777‐791. DOI: 10.1111/j.1752‐1688.2010.00451.x Abstract: Lake surface regimes are fundamental attributes of lake ecosystems and their interaction with the land and atmosphere. High latitudes may be particularly sensitive to climate change, however, adequate baselines for these lakes are often lacking. In this study, we couple monitoring, remote sensing, and modeling techniques to generate baseline datasets of lake surface temperature and ice cover in the Alaskan Subarctic and Arctic. No detectable trends were observed during this study period, but a number of interesting patterns were noted among lakes and between regions. The largest Arctic lake was relatively unresponsive to air temperature, while the largest Subarctic lake was very responsive likely because it is fed by glacial runoff. Mean late summer water temperatures were higher than air temperatures with differences ranging from 1.7 to 5.4°C in Subarctic lakes and from 2.4 to 3.2°C in Arctic lakes. The warmest mean summer water temperature in both regions was in 2004, with the exception of Subarctic glacially fed lake that was highest in 2005. Ice‐out timing had high coherence within regions and years, typically occurring in late May in Subarctic and in early‐July in Arctic lakes. Ice‐on timing was more dependent on lake size and depth, often varying among lakes within a region. Such analyses provide an important baseline of lake surface regimes at a time when there is increasing interest in high‐latitude water ecosystems and resources during an uncertain climate future.
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