| Citation |
Nelitz, M., K. Wieckowski, M. Porter, K. Bryan, F. Poulsen, and D. Carr. (2010) Evaluating the vulnerability of freshwater fish habitats to climate change and identifying regional adaptation strategies in the Cariboo-Chilcotin, ESSA Technologies Ltd. Prepared for Fraser Salmon and Watersheds Program. |
| Abstract/Description or Keywords |
The fourth assessment report from the Intergovernmental Panel on Climate Change (Parry et al. 2007) defines vulnerability as: “the degree to which a system is susceptible to, and unable to cope with, adverse effects of climate change, including climate variability and extremes. Vulnerability is a function of the character, magnitude and rate of climate change and the variation to which a system is exposed, its sensitivity and its adaptive capacity.” Across British Columbia the projected effects of climate change are towards increasing air temperatures with the largest increases in the north and during the winter, and variable changes in precipitation especially drier conditions during the summer and in the south with wetter conditions in the north (Rodenhuis et al. 2007; Pike et al. 2008). By the 2050s average annual air temperatures and precipitation in the Cariboo-Chilcotin are predicted to increase from 2.0-2.5 °C and 5-20% respectively, while in some locations summer precipitation is expected to decrease by as much as 5% (Figure 1). This overview of the vulnerability of the province and region is consistent with those projections from other global or regional studies. However, to understand the implications of these changes at a regional scale, we need to make the connection to the ecosystem goods and services that human communities value and upon which they rely. In British Columbia both historic evidence and future projections demonstrate that these kinds of climate effects will translate to alterations in other physical conditions, including changes in forest cover (Hamann and Wang 2006; Aukema et al. 2006), snowpack (Leung and Qian 2003; MOE 2007), glaciers (Schiefer et al. 2007), stream flows (Leith and Whitfield 1998; Whitfield and Cannon 2000; Zhang et al. 2001; Whitfield et al. 2003; Merritt et al. 2006), and water temperatures (Foreman et al. 2001; Morrison et al. 2002; Farrell et al. 2008). Ultimately, changes in these conditions affect the vulnerability of freshwater fish habitats as climate change will alter the capacity of watersheds to store and release water and buffer against stream heating. As the timing of spring freshet becomes earlier, the summer low flow period will likely be extended and constrain the availability and amount of rearing habitats for juvenile salmonids. Given the inverse relationship between stream flow and water temperature, further declines in summer low flows will increase the vulnerability of streams to increases in air temperatures, thereby altering the thermal suitability of rearing habitats and creating thermal barriers to migration. Similar reductions in flow during the late summer and fall will further constrain the accessibility of spawning habitats in both space and time. |
