Climate change: How will it affect the Bow River?Climate change has hit mainstream media, even in Alberta. While sceptics may abound, the Intergovernmental Panel on Climate Change (IPCC) in its fourth assessment of the latest climate change-related literature expressed "very high confidence [a confidence rating of 9 out of 10 times] that the globally averaged net effect of human activities since 1750 has been one of warming" (IPCC 2007, 3). Many of us do believe it's happening, but do we understand how it will affect us—and our water sources? Do we understand that the state of our water cycle could drastically change, and is arguably changing already? Recent reports and a recent conference suggest how we might be affected and how we could proceed to improve our situation. The semi-arid Bow River watershedLiving in the Bow River watershed, much of our water comes from the mountains, our water towers. Water is stored there as snow and ice until the summer, after the spring rains have tapered off. But what happens when less water is stored as snow? When the glacial ice has melted and is unable to provide those late summer base flows so crucial for fish and other aquatic life—not to mention our human demands? The Bow River flows from the mountains through the foothills and grasslands, past Calgary and other communities, farms, and other water users, into the South Saskatchewan River, which eventually drains into Hudson's Bay. The Bow River and South Saskatchewan River flow through one of the driest areas of Canada: the Palliser Triangle. The Palliser Triangle, named after Captain John Palliser, a British explorer, is part of the Northern Great Plains, which extends up from the US mid-west to the southeastern corner of Alberta. The Palliser Triangle and the Plains lie in the rain shadow of the Rocky Mountains, which, along with the mountains in British Columbia, strip much of the precipitation from moisture-laden clouds that form over the Pacific Ocean and drift east (Nemanishen 1998). Thus, the Triangle (and part of the Bow watershed) is the driest region of Canada and is recognized to be the region most vulnerable to negative impacts of climate change. Here, drought and lack of soil moisture are already recurrent problems. Despite the aridity and highly variable climate, this region produces at least half of Canada's agricultural output (Warren and Lemmen 2004) — with significant help from irrigation. Recent reports demonstrate that we, in the Bow River watershed, are indeed beginning to experience long-term changes in our climate and can only expect more change in the coming 50 to 100 years. Changes include increased temperature, which will result in more frequent drought and water shortages, increased precipitation in some areas, and flooding as well as a shift upwards of biomes, meaning Calgary will be more like Lethbridge in 2050 and Edmonton more like Lethbridge in 2080. What key changes will a changing climate cause?Many regions of Canada, including the Prairies will experience:
Because much of the South Saskatchewan River Basin (SSRB) lies in or near the Palliser Triangle, the SSRB is highly vulnerable to the negative impacts of climate change. We, in the SSRB, will likely face: Increasing temperaturesOne report suggests that temperatures will increase, ranging from increases of 1.5°C to 2.8°C by 2050 (Martz et al. 2007). Already Calgary and Banff areas have increased by 1 degree in the last 65 years (BRBC 2005). Another study shows that, by 2050s, Calgary's annual mean temperature is predicted to be similar to, or warmer than, that currently observed at Lethbridge and Medicine Hat (Barrow and Yu 2005). Grande Prairie and Fort McMurray won't reach Lethbridge and Medicine Hat temperatures until the 2080s. Melting glaciersWarmer temperatures are already causing glaciers to melt more than accumulate ice. Thus, glaciers are receding. If they continue to recede, initially the increase in melt water will increase stream flows in the summer; but over time summer stream flow will decrease, according to the IPCC. Natural Resources Canada (2007), however, states historical stream flow data indicate that we may have passed through this phase of increased stream flow, and we may be in a phase of long-term declining stream flows. Total glacial cover in the Rocky Mountains is, in fact, approaching the lowest it has been in 10,000 years (NRCan 2007). Although glaciers contribute on average only 2.5% to the total annual flow of the Bow River, in low flow years, glaciers contribute up to 16%. In 1970, the lowest flow year on record, 47% of the August flows came from glacial meltwater (BRBC 2005). Therefore, these glaciers are especially important during drought years and soon they may not be around to help us through the dry years. More active precipitation cycleThe study by Martz et al (2007) shows there could be a modest decrease or increase in precipitation, depending on the climate model used. However, by the 2080s, precipitation is projected to increase around Alberta. But, less of this precipitation will fall as snow. Instead, there will be more rain-on-snow events and winter stream flows will increase, leaving less water stored in the snowpack for the drier summer months. Change in timing of stream flowChanges in the precipitation cycle will change the timing of stream flows, from small streams to rivers. High river flows will happen earlier in the spring and low flows will begin earlier in the summer. Lower summer flows will result in greater water shortages during times of peak demand (i.e., summer). Accelerated evaporationAlthough studies predict higher precipitation in the longer term, the higher temperatures will accelerate evaporation from water bodies. Therefore, one study tells us there will be an average decrease in water supply of 8.4% across watersheds in the SSRB. The decrease in flow could be the most in the Red Deer River basin at -13% on average, followed by the Bow River basin at -10% by 2050 (Martz et al 2007). Effects to groundwaterClimate change will also affect groundwater, especially shallow groundwater. Because shallow groundwater is generally connected to surface water, its flows could diminish as stream flows decrease. Deeper groundwater could become overexploited due to water shortages and be negatively impacted because it takes longer for deep groundwater to recharge. Overall, the depth and nature of groundwater affects its sensitivity to climate change, but groundwater will likely be affected in some way (NRCan 2007). More extreme eventsClimate change will likely increase the frequency and intensity of extreme events (flooding, drought, hail and windstorms). These events can play havoc to natural and human-made infrastructure, with short- and long-term consequences. These events can have many effects, including effects on water quality. One recent study of the Elbow River watershed (the source of 40% of Calgary's drinking water) suggests that the likelihood of higher stream flows in the spring, and flooding, will increase based on climate change modelling results. The study indicates a trend of increasing temperatures in February and March, and points to the possibility of increased precipitation in May. Because this watershed, a sub-watershed of the Bow River watershed, is highly influenced by snowmelt and spring rains, high flows generally occur in May, June, and July, high flows in the spring could increase, and the intensity and frequency of flooding will increase. Floods in 1995 and 2005 created significant havoc in Calgary and surrounding areas, and climate change could worsen future flooding events. Also, if rain-on-snow events happen more frequently and the snowpack begins to melt earlier, flooding will happen earlier in the spring and flows in the summer will be lower sooner. This consequence can be exacerbated by land uses in the watershed, such as timber harvesting, creation of linear features like roads, and residential development. As mentioned earlier, the likelihood of drought could also increase having particular damage on agriculture. How will these changes affect ecosystems?Seasonal shifts in flow regimes, caused by earlier snow melt and more rain in the winter rather than snow, could cause loss of habitat, species extinction, and increased water contamination. Climate change could change forest distribution and increase forest disturbances, such as fires and insect defoliation. These disturbances could affect the ability of the forest to store and filter water (NRCan 2007). How will these changes affect us?Semi-arid southern Alberta is particularly vulnerable to fluctuations in water availability. Domestic users and users of water for livelihood purposes are all at risk. In semi-arid southern Alberta, climate change would directly affect water demand for domestic uses. Outdoor domestic water uses (e.g., gardening and lawn watering) and drinking-water demand tend to increase in warmer, drier conditions. Yet, there will likely be less water available. Although climate change will lengthen the growing season and increase precipitation, precipitation timing and accelerated evaporation will decrease water supplies for agriculture. Warmer, drier conditions will increase demand by agricultural, particularly irrigation, in the SSRB. Irrigation consumption could increase by 23% by 2046. Meanwhile, climate change is likely to reduce water availability by approximately 546 million cubic meters between 1996 and 2046 (Martz et al 2007). Already Alberta agriculturalists use over 70% of the water allocated from the Bow River. Increasing temperatures of surface water can have a direct impact on industrial operations by decreasing the efficiency of cooling systems, and thereby reduce plant outputs (Martz et al 2007). Changes in precipitation and reduced glacier cover in the mountains will affect downstream summer flows and, as a result, hydroelectric operations. Less water means rivers won't be able to dilute poor quality water to the same degree as it does now. Rivers will be less able to handle water pollution and assimilate wastewater. Even now we have water quality problems, from wastewater treatment plants and urban and agricultural runoff, for example. Increased demand by economic and domestic human users will increase the conflict with ecological in-stream needs for water and the ability to retain ecosystem sustainability. What can we do about it?First, combat climate change by using less energy and contributing less to the cause of climate change in your everyday life and encouraging change in business and government decisions. Second, be ready for climate change and the consequent vagaries of more extreme weather. To protect the health of our aquatic ecosystems, which provide us so many services and resources, we need to make sure we don't take too much water from our rivers, lakes, and wetlands, or from groundwater sources. If we take too much water or pollute it too much, we will destroy the capacity of these systems to adapt to change, and a changing climate. We need to protect the resiliency of our natural systems. We need to protect fish habitat and the spaces along rivers and beside lakes and wetlands. We need to protect our groundwater sources so that they can keep providing base flows during drier times of year, flows that are so critical to aquatic life. "[C]ritical ecological (in-stream flow) needs plus baseline human consumptive needs must operate within overall water availability, leaving an unallocated portion of water available (essentially, a "buffer") to absorb all additional demands, including consumptive growth and climate change as well as the uncertainty and variability associated with both" Martz et al 2007 The most frequently recommended adaptation options for the water resources sector include (Martz et al 2007):
Some actions to predict and mitigate the impacts of climate change and human water use (Sandford 2007):
A recent conference on climate change, hosted by Canmore-based Western Watersheds Climate Research Collaborative (WWCRC) from November 23-25, 2007, proposed creation of a cooperative joint-research and outreach framework to establish greater collaboration among government, industry, and research organizations in Canada and abroad. This collaboration could "establish common interest, reduce duplication of effort and build partnerships that will work to actively translate our own collective scientific research results and similar results from all over the world into language the average Canadian can understand and decision-makers can act upon to ensure effective adaptation to climate change impacts" (Sandford 2008). Such collaboration will bring about a much-needed expanded hydro-meteorological monitoring system throughout the Rocky Mountains, first to be tested and modelled in the upper Bow River watershed. Such a system is "crucial to the management of growing water scarcity concerns on the prairie and to the understanding of how to properly identify and to adapt to actual and potential climate change impacts on Alberta's precious resources" (Sandford 2008). The hydro-meteorological observatory to be created in the Bow watershed could be a model for similar monitoring into other river basins beginning in the Rocky Mountains. Already collaboration of EPCOR, the Bow River Basin Council, Alberta Environment, the WWCRC, and others has led to a comprehensive climate vulnerability assessment for the Rocky Mountains and Eastern Slopes in Alberta (Sandford 2008). This will help point the way for future action in the Bow watershed. For the latest on how climate change will affect the Prairies, visit:
Sources:Barrow, Elaine and Ge Yu. 2005. Climate Scenarios for Alberta. Prairie Adaptation Research Collaborative and Alberta Environment. Bow River Basin Council. 2005. Nurture, Renew, Protect: The 2005 Report the State of the Bow River Basin. Intergovernmental Panel on Climate Change (IPCC). 2007. Climate Change 2007: The Physical Science Basis: Summary for Policy Makers. Geneva. United Nations Environmental Programme and World Meteorological Organization. Martz, Lawrence, Joel Bruneau and J. Terry Rolfe (eds). 2007. Climate Change and Water: SSRB Final Technical Report. Natural Resources Canada (NRCan). 2007. Palliser Triangle Global Change Project. Nemanishen, Walter. 1998. Drought in the Palliser Triangle: A Provisional Primer. PFRA Drought Committee. Rocky Mountain Outlook. November 14, 2007. Forum to host climate change experts. Sandford, Robert. 2007. A Century of Science at the Peyto Glacier: A Case for More Comprehensive Hydro-meteorological Monitoring in the Canadian Rockies: A Review by R.W. Sandford. University of Lethbridge's Western Watersheds Climate Research Collaborative. Sandford, Robert. 2008. The First Annual International Climate Change Forum Conference Summary, 2007. November 23-25. The Western Watersheds Climate Research Collaborative. Valeo, C., Z. Xiang, F.J-C. Bouchart, P. Yeung, and M.C. Ryan. 2007. Climate change impacts in the Elbow River watershed. Canadian Water Resources Journal. Vol. 32(4): 285-302. Warren, Fiona J. and Donald S. Lemmen. 2004. Climate Change Impacts and Adaptation: A Canadian Perspective. Natural Resources Canada (NRCan). |
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