Dec 14, 2011 - findings suggest the 20th century has been characterized ... 20th century climate change in shallow tundra ponds, western Hudson.
GEOPHYSICAL RESEARCH LETTERS, VOL. 38, L23402, doi:10.1029/2011GL049766, 2011
Divergent hydrological responses to 20th century climate change in shallow tundra ponds, western Hudson Bay Lowlands Brent B. Wolfe,1 Erin M. Light,1 Merrin L. Macrae,2 Roland I. Hall,3 Kaleigh Eichel,3 Scott Jasechko,4 Jerry White,3 LeeAnn Fishback,5 and Thomas W. D. Edwards4 Received 21 September 2011; revised 7 November 2011; accepted 8 November 2011; published 14 December 2011.
[1] The hydrological fate of shallow tundra lakes and ponds under conditions of continued warming remains uncertain, but has important implications for wildlife habitat and biogeochemical cycling. Observations of unprecedented pond desiccation, in particular, signify catastrophic loss of aquatic habitat in some Arctic locations. Shallow tundra ponds are a ubiquitous feature in the western Hudson Bay Lowlands (HBL), a region that has undergone intense warming over the past 50 years. But it remains unknown how hydrological processes in these ponds have responded. Here, we use cellulose-inferred pond water oxygen isotope records from sediment cores, informed by monitoring of modern pond water isotope compositions during the 2009 and 2010 ice-free seasons, to reconstruct hydrological conditions of four shallow tundra ponds in the western HBL over the past three centuries. Following an interval of relative hydrological stability during the early part of the records, results reveal widely differing hydrological responses to 20th century climate change among the study sites, which is largely dependent on hydrological connectivity of the basins within their respective surrounding peatlands. These findings suggest the 20th century has been characterized by an increasingly dynamic landscape that has variably influenced surface water balance – a factor that is likely to play a key role in determining the future water balance of ponds in this region. Citation: Wolfe, B. B., E. M. Light, M. L. Macrae, R. I. Hall, K. Eichel, S. Jasechko, J. White, L. Fishback, and T. W. D. Edwards (2011), Divergent hydrological responses to 20th century climate change in shallow tundra ponds, western Hudson Bay Lowlands, Geophys. Res. Lett., 38, L23402, doi:10.1029/ 2011GL049766.
1. Introduction [2] In northern landscapes, shallow lakes and ponds serve as important habitat for wildlife, play a key role in global biogeochemical cycles and provide natural resources for indigenous communities, but may be particularly vulnerable to climate change [Rouse et al., 1997; Prowse et al., 2006]. 1 Department of Geography and Environmental Studies, Wilfrid Laurier University, Waterloo, Ontario, Canada. 2 Department of Geography and Environmental Management, University of Waterloo, Waterloo, Ontario, Canada. 3 Department of Biology, University of Waterloo, Waterloo, Ontario, Canada. 4 Department of Earth and Environmental Sciences, University of Waterloo, Waterloo, Ontario, Canada. 5 Churchill Northern Studies Centre, Churchill, Manitoba, Canada.
Copyright 2011 by the American Geophysical Union. 0094-8276/11/2011GL049766
Longer ice-free seasons, changing moisture regimes, thawing permafrost and accelerating thermokarst processes during the latter part of the 20th century have been associated with numerous observations that the areal coverage of shallow surface water is increasing in some areas and yet declining elsewhere [e.g., Smith et al., 2005; Riordan et al., 2006; Marsh et al., 2009; Carroll et al., 2011]. Reduced effective moisture has caused complete desiccation in some basins, leading ultimately to loss of aquatic habitat [Smol and Douglas, 2007]. In other cases, directional change simply cannot be identified due to short-term fluctuations in meteorological conditions [e.g., Plug et al., 2008]. Many studies have relied upon field surveys, instrumental meteorological records or remote sensing imagery to draw conclusions regarding cause and effect, but these sources of data frequently provide insufficient temporal context to clearly identify linkages between 20th century climate change and the hydrological responses of shallow ponds in northern regions. Furthermore, how these critical freshwater landscapes may evolve in the future as a consequence of ongoing climate change remains largely unknown, although widespread disappearance of shallow ponds has been predicted [Smith et al., 2005; Avis et al., 2011]. [3] The Hudson Bay Lowlands (HBL) is one of the most extensive subarctic wetland landscapes in the world. In the western HBL, near Churchill (Manitoba, Canada), shallow ponds comprise 25% of the landscape and provide important habitat for waterfowl and other wildlife [Macrae et al., 2004]. These ponds are typically
