Assessing Climate Change Vulnerability of Breeding Birds in Arctic ...

Section 1. IntroductionOf all places on the earth, climate change isoccurring most dramatically at the poles(Gillett et al. 2008). In the Arctic, airtemperature has increased at almost twicethe global average rate in the past 100 years,accompanied by significantly alteredweather patterns, increased glacial and polarpack ice melt, and sea level rise (IPCC2007). More specifically, in Arctic Alaskamean annual temperature is rising at a rateof 0.45 °C per decade (Data from M.Shulski reported in Martin et al. 2009;Figure 1.1). Over the next 60 years, meanannual temperatures are expected to increaseapproximately 5 °C (Figure 1.2) and to 7 °Cby the end of the century with most of thewarming occurring in winter (Martin et al.2009). Annual precipitation is expected toincrease 20-40% over the next 60 years(Figure 1.3) although increasingtemperatures may lessen the effects ofincreased precipitation by driving anincrease in evapotranspiration rates (TWSSNAP http://www.snap.uaf.edu/data.php).While in some Arctic sites there is evidenceof tundra drying, the pattern is spatiallyheterogeneous (e.g., Riordan et al. 2006). Itis uncertain whether the future will bring anet annual drying or moistening. Moreover,it is unclear how surface hydrology andgeomorphology changes will eitherexacerbate or compensate for shifts inatmospheric moisture (Martin et al. 2009).Regionally, recent temperature and moisturechanges are leading to warming permafrost(Romanovsky et al. 2007), increased coastalerosion (Jones et al. 2009), more frequentfires (Racine and Jandt 2008), and shrubinvasion (Tape et al. 2006), likely alteringgeomorphology, hydrology, and habitatstructure (see Martin et al. 2009 for athorough review).Key resources of concern in the Arcticare the vast productive wetlands in northernAlaska (particularly in the Arctic CoastalPlain) and the birds that migrate from allover the globe during the brief summerseason to breed. Avian research in the regionpoints to the unique importance of largeparts of Arctic Alaska in harboring some ofthe most important avian breeding groundsin the entire circumpolar Arctic (Andres etFigure 1.1. 50-year trend in mean annual temperature at seven sites on the North Slope (Source: M.Shulski in Martin et al. 2009).3