Linda Mortsch

Climate Change Impacts on the Hydrology of the Great Lakes-St. Lawrence System

A review of the current state of knowledge on climate change due to an ’enhanced greenhouse effect’ and the response of the climate and hydrologic systems to a changing atmosphere is provided. In particular, the survey presents historic trends in and the impacts of climate change on temperature, precipitation, evapotranspiration, runoff and Great Lakes levels. While much of the impacts research in the Great Lakes-St. Lawrence basin has used equilibrium 2 × CO2 scenarios, the transient scenarios for 2030 and 2050 from the Canadian Centre for Climate Modelling and Analysis and the United Kingdom Hadley Centre coupled atmosphere-ocean global circulation models are also described. If the significant declines in runoff and lakes levels suggested by climate change scenarios are realized, there could be serious supply-demand mismatches and water allocation issues. The issue of climate change reinforces the need for continued cooperative planning and management of the water resources of the Great Lakes-St. Lawrence basin.

Unequal Vulnerability to Flood Hazards: “Ground Truthing” a Social Vulnerability Index of Five Municipalities in Metro Vancouver, Canada

Indexes that measure social vulnerability to hazards have gained acceptance as a research tool that can inform local policymaking. Many indexes, however, are created remotely by researchers without using the input of those working in local policy. If practitioners are involved in creating an index that they find accurate and useful, it is more likely they will incorporate the findings of the index in local policy decisions. This article describes the process of ground truthing a social vulnerability index with practitioners working in five municipalities in Metro Vancouver and how the index was then revised to reflect their input. This process involved presenting an index to focus groups of municipal practitioners for their feedback and conducting a survey of participants that was then used to assign weights to the variables in the index. The study found that practitioners were generally accepting of the research approach to quantifying social vulnerability by place, although they often had specific concerns regarding the methodology and offered suggestions to make the index more reflective of the local context. The process of revising the index illustrates that local practitioner input can be used to create a measure of social vulnerability to hazards that is meaningful to those working in the community.

Using vulnerability and resilience concepts to advance climate change adaptation

Adaptation is necessary if we are to minimize risks associated with climate change impacts. Vulnerability and resilience are two important concepts in the literature on hazards and climate change but have been used in a variety of ways to investigate human interaction with a hazardous environment. The result is widespread adoption of the terms but confusion about their relationship and how best they can advance work on climate change adaptation. This paper critically reviews the different understandings of the concepts and how they relate, and then proposes a framework that integrates vulnerability and resilience in order to advance adaptation thinking, planning and implementation. The paper concludes with a description of how the framework will apply findings on unequal social vulnerability to inform adaptation options that increase resilience in coastal cities.

Climate and water availability indicators in Canada: Challenges and a way forward. Part I – Indicators

Climate variability influences the availability of water resources throughout Canada, and projected climate change is anticipated to affect future water availability. This is the first paper of a three-part analysis of water availability indicators in Canada (Parts II and III, this issue). The concept of water availability has been described in different ways in the literature. In Part I, the various approaches for estimating water availability are reviewed and compared, with a focus on Canadian studies. Global examples are used when necessary. The approaches to estimate water availability are organized into three categories: (1) climate-based indicators, (2) hydrology-based indicators and (3) water demand/supply-based indicators. Climate-based indicators use variables such as precipitation, and potential or actual evapotranspiration to calculate water budgets. Widely used meteorological drought indices that calculate moisture surpluses and deficits are also examined. Hydrology-based indicators focus on variables such as observed or modeled streamflow, or runoff. Water demand/supply-based indicators tend to focus on comparing the volume of available water with the amount of water used. Some conclusions on the status of water availability estimates in Canada are provided.

A Resiliency Assessment of Ontario's Low-water Response Mechanism: Implications for Addressing Management of Low-water Under Potential Future Climate Change

Investigation on the performance of Ontarios low-water response (OLWR) mechanism during current periods of drought is an important research task given that climate variability and change may alter the frequency and intensity of extreme events. Factors that influence the resilience of the OLWR mechanism and the ability of the mechanism to guide water allocation decisions are identified based on interview responses from 13 OLWR team members in the Grand River watershed. Results of this study indicate that the OLWR mechanism may not be resilient enough to operate under conditions of serious low-flow and that aquatic ecosystems could be compromised during times of serious water scarcity. Water use allocation priority, water use classification categories, ambiguity surrounding the ecosystem-based approach to water management, and the tendency of the low-water response mechanism to operate in reactive mode were identified as issues that hinder the way the mechanism is currently administered, suggesting that the mechanism may not operate in a resilient fashion under a changing climate. The infrequent occurrence of drought in Ontario results in a continuous manifestation of the hydro-illogical cycle which is perhaps one reason why shortcomings of the mechanism remain unaddressed. A challenge is to find practical ways of enhancing the resilience of the low-water response mechanism using a proactive approach to effectively manage water resources during times of drought. Creation of a more resilient low-water response plan will ultimately enhance future drought-preparedness under projected changed climate conditions for Ontario and aid adaptation strategies to reduce future vulnerability.

Response of vegetation communities in three Lake Huron fens to historical water level fluctuations

Historical changes in wetland classes in three shoreline fens, Baie du Dore, Oliphant, and Howdenvale, along the eastern shoreline of Lake Huron were analyzed to determine responses to fluctuating water levels. Wetland classes (lake, floating emergent, emergent marsh, meadow marsh, fen, and exposed substrate) were delineated through interpretation of aerial photographs for the period 1938 to 1995. Scan vectorization was used to develop a digital data base of wetland classes. Spatial and temporal analyses, conducted in a Geographic Information System (GIS), allowed comparison of trends among and within wetland classes which were linked to water level conditions. In periods with low water levels, overall wetland area increased primarily through expansion of the exposed substrate class lakeward; although meadow marsh also contributed to the increase. While wetland area increased during low water levels, exposed substrate did not markedly add to wetland habitat value but represents potential new wetland area that can be recolonized from seed banks. During high water levels, wetland area decreased as the lake class expanded inland and exposed substrate contracted or disappeared. Fen remained consistent in areal extent and location for most years at Howdenvale, but fen at Baie du Dore expanded with lower water levels, and contracted and became more fragmented with higher levels. At Oliphant, during low water levels fen area did not change, and with high levels the lake flooded the fen. With high water levels, lake area and wetter classes dominated and migrated inland. Under low water level conditions, lake was replaced by exposed substrate and drier wetland classes expanded, but did not necessarily colonize exposed substrate.

Climate and water availability indicators in Canada: Challenges and a way forward. Part III – Future scenarios

Following from Parts I and II of this series (this issue), some common approaches for developing and assessing future scenarios of water availability are reviewed, along with recent case studies of Canadian watersheds. The results of future changes in drought related to climate change are influenced by the choice of indicators. For the Standardized Precipitation Index (SPI), small changes in drought frequency and severity are projected over southern Canada, reflecting the influence of increases in future annual precipitation only. However, assessments using the Palmer Drought Severity Index (PDSI) reveal dramatic increases in the potential for future droughts since this indicator incorporates the combined influences of higher temperatures, soil moisture capacity and precipitation to estimate evapotranspiration. Regarding projected changes in runoff, watersheds in British Columbia tend to show increases in annual and winter runoff. Some watersheds show projected decreases in summer runoff. In the southern Prairies, most watersheds show projected decreases in annual and summer runoff. In Ontario and Quebec, results are mixed. Lake levels in the Great Lakes are projected to decline under most scenarios, but results differ between regional and global climate model-based scenarios due to differences in how lake evaporation is calculated. In New Brunswick, Labrador and northern Quebec, streamflow is projected to increase. Uncertainties in future projections emerge due to differences between climate scenario generating methods, and between hydrologic models used for the assessments. This paper concludes with some thoughts on addressing important research questions related to future scenarios of water availability in Canada. For scenario-based assessments, hydrologic model inter-comparisons might yield some useful insights into uncertainties in model structure that affect evaporation, evapotranspiration and snowmelt calculations. Scenarios developed for assessments should include both future climate and projected land use/cover changes and, where necessary, integration of potential reduction in glacier volume. Finally, as scenarios from regional climate models become more readily available, there may be more opportunity to explore how runoff projections could be applied to basin-scale routing models.

Climate and water availability indicators in Canada: Challenges and a way forward. Part II – Historic trends

Climate variability is recognized as an important influence on the availability of water throughout Canada, and projected climate change is anticipated to alter the amount, timing and distribution of water. This is Part II of a three-part (Parts I and III, this issue) analysis of water availability in Canada. Part II surveys current research, primarily Canadian in origin, on historical trends in climate and hydrologic indicators relevant to assessing water availability. Information on hydro-climate trends is not evenly distributed across Canada. Hydrologic trend research focuses on the North, British Columbia and the Prairies (Saskatchewan) with some research in Quebec, very little in Ontario and minimal analysis for Atlantic Canada. Overall, there is less research on trends in climatological indicators (drought, evapotranspiration, soil moisture); generally, the focus is on the Prairies. Hydrologic trends from basin-scale case studies are reported but inter-comparison is constrained by different periods of analysis. Trends vary by region. Generally, in the Prairies annual streamflow is decreasing, while results for the Yukon, BC, Ontario and Quebec are mixed. There is no clear signal on drought trends. Drought results are influenced by location, data (instrumental or paleo-climate), period of record and treatment of components in the drought index. For historic trend studies, observations with long duration, spatial coverage and minimal human-influences are crucial. These limitations in data affect streamflow assessment, but analysis of evapotranspiration and soil moisture trends is constrained by additional challenges of measurement, modelling and few data sets. Future research recommendations include combining climate change trend assessment with potential influences of large-scale atmospheric circulation patterns on inter-annual hydro-climatological variability. There is a need to explore the uncertainty associated with and methodological challenges in statistical analysis of hydro-climate time series. At present, there have been no rigorous detection and attribution studies of hydrology indicators in Canada.

Principles for climate-related resettlement of informal settlements in less developed nations: a review of resettlement literature and institutional guidelines

The severity of climatic changes threatening urban coastal areas is introducing and intensifying environmental hazards that are endangering physical safety and livelihood security. This paper considers retreat, one of three broad adaptation options proposed by the Intergovernmental Panel on Climate Change, as a possible climate change adaptation strategy for low-income communities in less developed nations. Resettlement as climate change adaptation is a developing concept, with minimal guidelines and academic literature on the topic. Thus, this review expands beyond climate change, considering three literature themes surrounding resettlement: (1) climate change, (2) hazard and natural disasters (i.e. floods, hurricanes, and earthquakes), and (3) economic development (i.e. dam construction and natural resource extraction). The review extracts successful resettlement planning and approaches, as well as the lessons learned, to identify five principles for resettlement in a climate change context: Proactivity, Communication and Participation, Permanence, Compensation, and Livelihood Protection. The results of the analysis suggest five principles that can be used as a guideline for implementing resettlement as climate change adaptation for low-income and informal communities in less developed nations. Ultimately, these recommendations can be used to assess the appropriateness and feasibility of employing resettlement as managed retreat in less developed nations.

Barriers and Drivers of Planning for Climate Change Adaptation across Three Levels of Government in Canada

ABSTRACT This study investigates the factors that constrain and enable adaptation planning for increasing flood risk in Canada. It uses a multiple-methods, multi-scalar approach to identify interconnected barriers and drivers that operate across municipal, provincial, and federal levels of government in Vancouver and Surrey, British Columbia. Through a policy content analysis (n = 54) and in-depth interviews with planners and other practitioners (n = 31), the study finds five major barriers to the mainstreaming of climate change adaptation: inadequate collaboration, absence of senior level political leadership, lack of public awareness, insufficient financial and staff capacity, and misalignment of policies within and between levels of government.