Impacts of Climate Change on Water

Abstract

EXECUTIVE SUMMARY There is increasing evidence that the overwintering distributions of many coastal waders have shifted in recent decades in response to warming. In the last decade, this has resulted in declines in usage of east coast sites in favour of The Netherlands, although during recent cold winters, this trend has been partially reversed. These changes have probably resulted from a redistribution of individuals rather than changes in survival, either in response to an altered tendency towards cold-weather movements or changing juvenile settlement patterns. There is increasing evidence that similar distribution changes have occurred in seaduck, which may be taking advantage of ice-free conditions in the Baltic, and in coastal wintering waterfowl. Little egret has become much more common on estuaries in winter in response to the increasing breeding population. Projected future increases in great white egret, cattle egret and glossy ibis populations also likely to become regular users of British estuaries in winter. Models project future increases in the abundance of many wintering wader and waterbird populations in the UK in response to projected warming, although some are projected to decline. Most current SPAs are likely to continue to support internationally important numbers of wintering waterbirds, even under a high-emissions 2080 scenario. Potential changes in sea level may alter estuarine sediment patterns, with likely impacts on wintering waterbird communities, particularly at sites where coastal defences are maintained. Significant warming is projected to reduce the Arctic and subarctic breeding ranges of wintering waterbirds by about 50 % by the end of the century. This suggests that despite improving winter conditions in the UK, wintering populations of many species here may decline.