Bird Species and Climate Change: The Global Status Report - WWF

Predicting the individual responsesof different species to a wide array ofhabitat changes on migration routesspanning the globe is difficult and ishindered by uncertainty in models anda lack of detailed studies (Barlein andHüppop, 2004). According to Saether(2000), “One frightening consequenceof these findings is that they illustratehow difficult it will be to reliably predictthe effects of large-scale regionalclimate change on ecological systems.”6.3.2 Wetland birds“Given the potentially seriousconsequences of globalwarming for waterfowlpopulations ... society hasyet another reason to act toslow greenhouse warmingand safeguard the future ofthese resources.”Sorenson et al., 1998Under 3-4°C of warming, 85 per centof all remaining wetlands could beeliminated (UNEP, 2005) -- a radicalalteration of wetland birds’ currenthabitat. Some European coastal areas,for example, are forecast to loose up to100 per cent of their wetland stock by2080 (IPCC, 2001b). As a result of thesechanges, 40 per cent of migratory birdspecies face impacts from predictedlowering of water tables, 53 per centfrom changes in water regimes overall.As noted above, these changes inwater regimes are actually the mostwidespread climatic threats to migratorybird species (DEFRA, 2005).Remaining wetlands will face anincreasingly variable hydrological cycle,which would leave inland wetlandsto dry out, resulting in lower speciesdiversity (see case study 3). Coastalmarshes will also be affected, dueto rising sea-level and changes inhydrological balance and severity. Asnoted in Section 2, habitat in estuariesand deltas will be lost if barriers preventa natural retreat as sea levels rise(coastal squeeze; UNEP, 2005; IPCC2001b). One of the most severe threatsto birds, this is a particular problem inEurope where landward extension ofsalt marshes is restricted by hard seadefences, for example by dams anddykes in the Wadden Sea (Böhning-Gaese and Lemoine, 2004; Bairlein andHüppop, 2004).In the Arctic, permafrost melting willcause lakes and wetlands to drainin some areas, while creating newwetlands in others. The balance of theseeffects is unknown, but major speciesshifts are likely as a result (ACIA, 2004).Bird Species and Climate Change: The Global Status Report58Climate Risk