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Item Change point detection of flood events using a functional data framework(Advances in Water Resources, 2020) Ben Alaya, Mohamed Ali; Ternyck, Camille; Dabo-Niang, Sophie; Chebana, Fateh; Ouarda, Taha B. M. J.Change point detection methods have an important role in many hydrological and hydraulic studies of river basins. These methods are very useful to characterize changes in hydrological regimes and can, therefore, lead to better understanding changes in extreme flows behavior. Flood events are generally characterized by a finite number of characteristics that may not include the entire information available in a discharge time series. The aim of the current work is to present a new approach to detect changes in flood events based on a functional data analysis framework. The use of the functional approach allows taking into account the whole information contained in the discharge time series of flood events. The presented methodology is illustrated on a flood analysis case study, from the province of Quebec, Canada. Obtained results using the proposed approach are consistent with those obtained using a traditional change point method, and demonstrate the capability of the functional framework to simultaneously consider several flood features and, therefore, presenting a comprehensive way for a better exploitation of the information contained in a discharge time series.Item Downscaling extremes—An intercomparison of multiple statistical methods for present climate(Journal of Climate, 2012) Bürger, Gerd; Murdock, Trevor Q.; Schoeneberg (Werner), Arelia T.; Sobie, Stephen R.Five statistical downscaling methods [automated regression-based statistical downscaling (ASD), bias correction spatial disaggregation (BCSD), quantile regression neural networks (QRNN), TreeGen (TG), and expanded downscaling (XDS)] are compared with respect to representing climatic extremes. The tests are conducted at six stations from the coastal, mountainous, and taiga region of British Columbia, Canada, whose climatic extremes are measured using the 27 Climate Indices of Extremes (ClimDEX; http://www.climdex. org/climdex/index.action) indices. All methods are calibrated from data prior to 1991, and tested against the two decades from 1991 to 2010. A three-step testing procedure is used to establish a given method as reliable for any given index. The first step analyzes the sensitivity of a method to actual index anomalies by correlating observed and NCEP-downscaled annual index values; then, whether the distribution of an index corresponds to observations is tested. Finally, this latter test is applied to a downscaled climate simulation. This gives a total of 486 single and 162 combined tests. The temperature-related indices pass about twice as many tests as the precipitation indices, and temporally more complex indices that involve consecutive days pass none of the combined tests. With respect to regions, there is some tendency of better performance at the coastal and mountaintop stations. With respect to methods, XDS performed best, on average, with 19% (48%) of passed combined (single) tests, followed by BCSD and QRNN with 10% (45%) and 10% (31%), respectively, ASD with 6% (23%), and TG with 4% (21%) of passed tests. Limitations of the testing approach and possible consequences for the downscaling of extremes in these regions are discussed.Item Introduction to explaining extreme events of 2014 from a climate perspective(Bulletin of the American Meteorological Society, 2015) Herring, Stephanie C.; Hoerling, Martin P.; Kossin, James P.; Peterson, Thomas C.; Stott, Peter A.The field of event attribution faces challenging questions. Can climate change influences on single events be reliably determined given that observations of extremes are limited and implications of model biases for establishing the causes of those events are poorly understood? The scientific developments in this report—now in its fourth year—as well as in the broader scientific literature, suggest that “event attribution” that detects the effects of long-term change on extreme events is possible. However, because of the fundamentally mixed nature of anthropogenic and natural climate variability, as well as technical challenges and methodological uncertainties, results are necessarily probabilistic and not deterministic. As the science advances, other questions are emerging. For what types of events can event attribution provide scientifically robust explanations of causes? Is near-real-time attribution possible? And, how useful are science-based explanations of extremes for society? We consider these questions in more detail.Item A new statistical approach to climate change detection and attribution(Climate Dynamics, 2017) Ribes, Aurélien; Zwiers, Francis W.; Azaïs, Jean-Marc; Naveau, PhilippeWe propose here a new statistical approach to climate change detection and attribution that is based on additive decomposition and simple hypothesis testing. Most current statistical methods for detection and attribution rely on linear regression models where the observations are regressed onto expected response patterns to different external forcings. These methods do not use physical information provided by climate models regarding the expected response magnitudes to constrain the estimated responses to the forcings. Climate modelling uncertainty is difficult to take into account with regression based methods and is almost never treated explicitly. As an alternative to this approach, our statistical model is only based on the additivity assumption; the proposed method does not regress observations onto expected response patterns. We introduce estimation and testing procedures based on likelihood maximization, and show that climate modelling uncertainty can easily be accounted for. Some discussion is provided on how to practically estimate the climate modelling uncertainty based on an ensemble of opportunity. Our approach is based on the “models are statistically indistinguishable from the truth” paradigm, where the difference between any given model and the truth has the same distribution as the difference between any pair of models, but other choices might also be considered. The properties of this approach are illustrated and discussed based on synthetic data. Lastly, the method is applied to the linear trend in global mean temperature over the period 1951–2010. Consistent with the last IPCC assessment report, we find that most of the observed warming over this period (+0.65 K) is attributable to anthropogenic forcings (+0.67 ± 0.12 K, 90 % confidence range), with a very limited contribution from natural forcings (−0.01 ± 0.02 K).Item How does dynamical downscaling affect model biases and future projections of explosive extratropical cyclones along North America’s Atlantic coast?(Climate Dynamics, 2018) Seiler, Christian; Zwiers, Francis W.; Hodges, Kevin I.; Scinocca, John F.Explosive extratropical cyclones (EETCs) are rapidly intensifying low pressure systems that generate severe weather along North America’s Atlantic coast. Global climate models (GCMs) tend to simulate too few EETCs, perhaps partly due to their coarse horizontal resolution and poorly resolved moist diabatic processes. This study explores whether dynamical downscaling can reduce EETC frequency biases, and whether this affects future projections of storms along North America’s Atlantic coast. A regional climate model (CanRCM4) is forced with the CanESM2 GCM for the periods 1981 to 2000 and 2081 to 2100. EETCs are tracked from relative vorticity using an objective feature tracking algorithm. CanESM2 simulates 38% fewer EETC tracks compared to reanalysis data, which is consistent with a negative Eady growth rate bias (−0.1 day). Downscaling CanESM2 with CanRCM4 increases EETC frequency by one third, which reduces the frequency bias to −22%, and increases maximum EETC precipitation by 22%. Anthropogenic greenhouse gas forcing is projected to decrease EETC frequency (−15%, −18%) and Eady growth rate (−0.2 day, −0.2 day), and increase maximum EETC precipitation (46%, 52%) in CanESM2 and CanRCM4, respectively. The limited effect of dynamical downscaling on EETC frequency projections is consistent with the lack of impact on the maximum Eady growth rate. The coarse spatial resolution of GCMs presents an important limitation for simulating extreme ETCs, but Eady growth rate biases are likely just as relevant. Further bias reductions could be achieved by addressing processes that lead to an underestimation of lower tropospheric meridional temperature gradients.Item Evaluating hydroclimatic change signals from statistically and dynamically downscaled GCMs and hydrologic models(Journal of Hydrometeorology, 2014) Shrestha, Rajesh R.; Schnorbus, Markus A.; Schoeneberg (Werner), Arelia T.; Zwiers, Francis W.This study analyzed potential hydroclimatic change in the Peace River basin in the province of British Columbia, Canada, based on two structurally different approaches: (i) statistically downscaled global climate models (GCMs) using the bias-corrected spatial disaggregation (BCSD) and (ii) dynamically downscaled GCM with the Canadian Regional Climate Model (CRCM). Additionally, simulated hydrologic changes from the GCM–BCSD-driven Variable Infiltration Capacity (VIC) model were compared to the CRCM integrated Canadian Land Surface Scheme (CLASS) output. The results show good agreements of the GCM–BCSD–VIC simulated precipitation, temperature, and runoff with observations, while the CRCM-simulated results differ substantially from observations. Nevertheless, differences (between the 2050s and 1970s) obtained from the two approaches are qualitatively similar for precipitation and temperature, although they are substantially different for snow water equivalent and runoff. The results obtained from the five Coupled Global Climate Model, version 3, (CGCM3)-driven CRCM runs are similar, suggesting that the multidecadal internal variability is not a large source of uncertainty for the Peace River basin. Overall, the GCM–BCSD–VIC approach, for now, remains the preferred approach for projecting basin-scale future hydrologic changes, provided that it explicitly accounts for the biases and includes plausible snow and runoff parameterizations. However, even with the GCM–BCSD–VIC approach, projections differ considerably depending on which of an ensemble of eight GCMs is used. Such differences reemphasize the uncertain nature of future hydroclimatic projections.Item Intercomparison of multi-model ensemble-processing strategies within a consistent framework for climate projection in China(Science China Earth Sciences, 2023) Zhu, Huanhuan; Jiang, Zhihong; Li, Laurent; Li, Wei; Jiang, Sheng; Zhou, Panyu; Zhao, WeihaoClimate change adaptation and relevant policy-making need reliable projections of future climate. Methods based on multi-model ensemble are generally considered as the most efficient way to achieve the goal. However, their efficiency varies and inter-comparison is a challenging task, as they use a variety of target variables, geographic regions, time periods, or model pools. Here, we construct and use a consistent framework to evaluate the performance of five ensemble-processing methods, i.e., multi-model ensemble mean (MME), rank-based weighting (RANK), reliability ensemble averaging (REA), climate model weighting by independence and performance (ClimWIP), and Bayesian model averaging (BMA). We investigate the annual mean temperature (Tav) and total precipitation (Prcptot) changes (relative to 1995–2014) over China and its seven subregions at 1.5 and 2 °C warming levels (relative to pre-industrial). All ensemble-processing methods perform better than MME, and achieve generally consistent results in terms of median values. But they show different results in terms of inter-model spread, served as a measure of uncertainty, and signal-to-noise ratio (SNR). ClimWIP is the most optimal method with its good performance in simulating current climate and in providing credible future projections. The uncertainty, measured by the range of 10th-90th percentiles, is reduced by about 30% for Tav, and 15% for Prcptot in China, with a certain variation among subregions. Based on ClimWIP, and averaged over whole China under 1.5/2 °C global warming levels, Tav increases by about 1.1/1.8 °C (relative to 1995–2014), while Prcptot increases by about 5.4%/11.2%, respectively. Reliability of projections is found dependent on investigated regions and indices. The projection for Tav is credible across all regions, as its SNR is generally larger than 2, while the SNR is lower than 1 for Prcptot over most regions under 1.5 °C warming. The largest warming is found in northeastern China, with increase of 1.3 (0.6-1.7)/2.0 (1.4-2.6) °C(ensemble’s median and range of the 10th–90th percentiles) under 1.5/2 °C warming, followed by northern and northwestern China. The smallest but the most robust warming is in southwestern China, with values exceeding 0.9 (0.6–1.1)/1.5 (1.1–1.7) °C. The most robust projection and largest increase is achieved in northwestern China for Prcptot, with increase of 9.1%(-1.6–24.7%)/17.9% (0.5–36.4%) under 1.5/2 °C warming. Followed by northern China, where the increase is 6.0%(-2.6–17.8%)/11.8% (2.4–25.1%), respectively. The precipitation projection is of large uncertainty in southwestern China, even with uncertain sign of variation. For the additional half-degree warming, Tav increases more than 0.5 °C throughout China. Almost all regions witness an increase of Prcptot, with the largest increase in northwestern China.Item Regional sources and sinks of atmospheric particulate selenium in the United States based on seasonality profiles(Environmental Science & Technology, 2023) Lao, Isabelle Renee; Feinberg, Aryeh; Borduas-Dedekind, NadineSelenium (Se) is an essential nutrient for humans and enters our food chain through bioavailable Se in soil. Atmospheric deposition is a major source of Se to soils, driving the need to investigate the sources and sinks of atmospheric Se. Here, we used Se concentrations from PM2.5 data at 82 sites from 1988 to 2010 from the Interagency Monitoring of Protected Visual Environments (IMPROVE) network in the US to identify the sources and sinks of particulate Se. We identified 6 distinct seasonal profiles of atmospheric Se, grouped by geographical location: West, Southwest, Midwest, Southeast, Northeast, and North Northeast. Across most of the regions, coal combustion is the largest Se source, with a terrestrial source dominating in the West. We also found evidence for gas-to-particle partitioning in the wintertime in the Northeast. Wet deposition is an important sink of particulate Se, as determined by Se/PM2.5 ratios. The Se concentrations from the IMPROVE network compare well to modeled output from a global chemistry-climate model, SOCOL-AER, except in the Southeast US. Our analysis constrains the sources and sinks of atmospheric Se, thereby improving the predictions of Se distribution under climate change.Item Possible increased frequency of ENSO-related dry and wet conditions over some major watersheds in a warming climate(Bulletin of the American Meteorological Society, 2020) Sun, Qiaohong; Miao, Chiyuan; AghaKouchak, Amir; Mallakpour, Iman; Ji, Duoying; Duan, QingyunPredicting the changes in teleconnection patterns and related hydroclimate extremes can provide vital information necessary to adapt to the effects of the El Niño–Southern Oscillation (ENSO). This study uses the outputs of global climate models to assess the changes in ENSO-related dry/wet patterns and the frequency of severe dry/wet events. The results show anomalous precipitation responding asymmetrically to La Niña and El Niño, indicating the teleconnections may not simply be strengthened. A “dry to drier, wet to wetter” annual anomalous precipitation pattern was projected during La Niña phases in some regions, with drier conditions over southern North America, southern South America, and southern central Asia, and wetter conditions in Southeast Asia and Australia. These results are robust, with agreement from the 26 models and from a subset of 8 models selected for their good performance in capturing observed patterns. However, we did not observe a similar strengthening of anomalous precipitation during future El Niño phases, for which the uncertainties in the projected influences are large. Under the RCP4.5 emissions scenario, 45 river basins under El Niño conditions and 39 river basins under La Niña conditions were predicted to experience an increase in the frequency of severe dry events; similarly, 59 river basins under El Niño conditions and 61 river basins under La Niña conditions were predicted to have an increase in the frequency of severe wet events, suggesting a likely increase in the risk of floods. Our results highlight the implications of changes in ENSO patterns for natural hazards, disaster management, and engineering infrastructure.Item A summary of climate change effects on watershed hydrology(BC Ministry of Forests, Range Forest Science Program, 2008-03) Pike, Robin G.; Spittlehouse, David L.; Bennett, Katrina E.; Egginton, V. N.; Tschaplinski, Peter J.The climate of British Columbia is changing, and with these changes will come many adjustments in watershed hydrology and, ultimately, in the use of water-related resources. Yet, because British Columbia is hydrologically diverse, the local responses to these anticipated changes will differ.Item Moving towards climate resilient health facilities for Vancouver Coastal Health(Lower Mainland Facilities Management, 2018-10) Lower Mainland Facilities Management; Pinna Sustainability; Pacific Climate Impacts Consortium (PCIC)Rising temperatures, shifting precipitation patterns, and extreme weather events are already affecting Vancouver Coastal Health (VCH) and our Communities of Care. Chronic stresses and acute shocks are creating a “new climate reality” for health facilities and service delivery, and reshaping our working context. With this series of reports, Lower Mainland Facilities Management (LMFM) demonstrates forward-thinking public sector leadership; positions health authorities to meet legislated requirements for addressing climate risk and reducing emissions; and, enables major infrastructure projects to assess climate resilience.Item Do meteorological, agricultural, and hydrological indicators all point to an increased frequency and intensity of droughts across Canada under a changing climate?(Atmosphere-Ocean, 2024) Bonsal, Barrie; Tam, Benita; Zhang, Xuebin; Li, Guilong; Philps, Lisa; Rong, RobinDroughts, one of the most significant natural hazards, are complex in nature with varying definitions typically tailored to the timing and/or duration of the episode along with associated impacts. Although previous investigations have assessed future drought occurrence across Canada, none have comprehensively and collectively assessed changes to meteorological, agricultural, and hydrological drought indicators using CMIP6 GCM projections. The main objective of this study was to assess future drought conditions across Canada at various temporal scales using standardized indices representing meteorological, agricultural, and hydrological droughts under multiple shared socio-economic pathways for the near (2041–2060) and far (2081–2100) future. On an annual basis, projected changes to all three drought indicators signify increased drying across the Prairies, portions of interior British Columbia, and most of Ontario. This drying is greater and covers more of the countryduring the warm season (April to September), while in summer and to a lesser extent autumn, widespread changes are only projected for meteorological and agricultural indicators. In spring, increased dry conditions are only prevalent in meteorological and hydrological indices. The cold season of October to March essentially shows little to no drying in any type of drought. Changes in all drought indices are amplified for higher SSPs andduring the late century. This study improves an understanding of the spatial and temporal variations in projected changes to various drought types across Canada in response to human-induced warming. While results from this analysis are applicable for nationwide drought assessments and drought management plans, they are less suitable for application at local scales where more detailed modelling may be required.Item Symposium addresses science of researching forest pests, climate change(Link, 2008) Flower, Aquila; Murdock, Trevor Q.Considerable uncertainty regarding forest pests, evidence of accelerated or unanticipated changes in forest ecosystems, and awareness of a potentially short time span in which to react and adapt prompted the recent Forest Pests and Climate Change Symposium in Victoria . Organized by the Pacific Climate Impacts Consortium, the symposium was designed with the goal of initiating a dialogue on the scientific requirements for research on forest pests and climate change.Item Climate change effects on watershed processes in British Columbia(Compendium of forest hydrology and geomorphology in British Columbia, 2010) Pike, Robin G.; Bennett, Katrina E.; Redding, Todd E.; Schoeneberg (Werner), Arelia T.; Spittlehouse, David L.; Moore, R. D. (Dan); Murdock, Trevor Q.; Beckers, Jos; Smerdon, Brian D.; Bladon, Kevin D.; Foord, Vanessa N.; Campbell, David A.; Tschaplinski, Peter J.A changing climate in British Columbia is expected to have many important effects on watershed processes that in turn will affect values such as water quality, water supplies, slope stability, and terrestrial and aquatic habitats. In many parts of British Columbia, the effects of too much or too little water have already been observed and it is possible that an increased probability of droughts, floods, and landslides will result in considerable socio-economic, biological, and (or) physical changes in the future (Spittlehouse and Stewart 2004; Walker and Sydneysmith 2007). The influence of climate change on watershed processes is critically important to understand and to manage for now and in the future, as these functions directly determine human well-being in terms of public health, the economy, communities, and cultures.Item Climate change and watershed hydrology: Part II - hydrologic implications for British Columbia(Streamline, 2008) Pike, Robin G.; Spittlehouse, David L.; Bennett, Katrina E.; Egginton, V. N.; Tschaplinski, Peter J.; Murdock, Trevor Q.; Schoeneberg (Werner), Arelia T.The accompanying article described recent climate changes in British Columbia. These changes are likely to result in adjustments in watershed hydrology and ultimately in our use of water-related resources. Increased risks of droughts, floods, and landslides will likely result in considerable socio-economic, biological, and physical changes. Future climate change will bring about greater changes and challenge our management of forest and range resources (Spittlehouse and Stewart 2003). To adapt to and in some cases mitigate the effects of climate change, it is necessary to understand the hydrologic implications for the future. This article (Part II) discusses eight broad hydrologic implications of climate change in British Columbia.Item Climate projections for the Okanagan region(2020-02) Regional District of North Okanagan; Regional District of Central Okanagan; Regional District of Okanagan-Similkameen; Pinna Sustainability; Natural Resources Canada; Okanagan Basin Water Board; Pacific Climate Impacts Consortium (PCIC)Climate change is challenging ecosystems, communities, and the economy. Wildfires, flooding, and drought have already overwhelmed local infrastructure, caused economic losses, and posed health risks to communities. Significant effort to reduce the reliance on fossil fuels as quickly as possible will slow, and has the potential to curb, climate change by the late century, making greenhouse gas emissions reductions a central part of any long-term adaptation strategy. Designing to current and future climate parameters is markedly more cost effective than reacting to climate shocks and stresses over time. This report is intended to support a local understanding of how climate across the Okanagan is projected to change, and inform regional planning on how to prepare for future climate events. This work is critical to maintaining wellbeing, including robust ecosystems, a thriving community, and a vibrant economy. Early efforts to prepare infrastructure and communities to climate change will reduce regional reliance on continued emergency management activations and support the ability of the region to thrive over time.Item Hydrologic models for forest management applications: Part 1: Model selection(Streamline, 2009) Beckers, Jos; Smerdon, Brian D.; Redding, Todd E.; Anderson, Axel; Pike, Robin G.; Schoeneberg (Werner), Arelia T.Predicting the effects of forest management on watershed processes and streamflow is a complex activity. Intricate linkages often exist between disturbances and consequences for an affected resource (e.g., Alila and Beckers 2001; Moore and Wondzell 2005; Pike et al. 2007). Models are increasingly used to investigate the potential effects of forest management on hydrologic processes and the resulting consequences to watershed values (e.g., Hudson and Quick 1997; Whitaker et al. 2002; Schnorbus and Alila 2004a; Alila and Luo 2007; Forest Practices Board 2007; Moore et al. 2007). To date, modelling efforts have been primarily limited to the research community, and the routine use of watershed models by resource managers and their consultants is not widespread. Because of the large scale and intensity of recent forest disturbances (e.g., mountain pine beetle) and the ramifications of climate change, a need exists to develop and apply models that will examine the potential effects on watershed function and that will support management decisions (Redding et al. 2009).Item Climate projections for the capital region(Capital Regional District, 2024) Pacific Climate Impacts Consortium (PCIC)The Earth’s climate system is warming, and signs of climate change are becoming evident across the planet. The capital region, located on Southern Vancouver Island and Gulf Islands of British Columbia (BC), is no exception. The Capital Regional District (CRD) has partnered with the Pacific Climate Impacts Consortium (PCIC) to produce high-resolution regional projections for temperature, precipitation, and related indices of extremes. These projections use the most up-to-date global modeling data (i.e., the Sixth Coupled Model Intercomparison Project, CMIP6) to illustrate how the region’s climate may change by the middle of this century. Information provided by this report and the accompanying data is intended to support decision makers and community partners in the region with an improved understanding of projected local climate change and related impacts.Item Hydrologic models for forest management applications: Part 2: Incorporating the effects of climate change(Streamline, 2009) Beckers, Jos; Pike, Robin G.; Schoeneberg (Werner), Arelia T.; Redding, Todd E.; Smerdon, Brian D.; Anderson, AxelIn Alberta and British Columbia, several detailed studies of climate trends, future climate predictions, and potential effects on hydrology have been conducted (e.g., Rodenhuis et al. 2007; Pike et al. 2008a, 2008b; Sauchyn and Kulshreshtha 2008; Walker and Sydneysmith 2008). These studies indicate that a changing climate will alter watershed processes, which in turn may affect many aspects of short- and long-term watershed management. From an operational perspective, watershed scale hydrologic models could be used to address a range of forest management uncertainties not limited to the assessment of future growing conditions, permanence of wetlands and small streams, and potential changes to flooding, low flow, and other disturbances (Pike et al. 2008b). However, using current hydrologic models to address such complex questions is expected to pose a number of challenges due to the inherent limitations of these models and data inadequacies that exist across British Columbia and Alberta.Item Climate projections for the City of Terrace(City of Terrace, 2022-12) City of Terrace; Pacific Climate Impacts Consortium (PCIC); Pinna SustainabilityTerrace has already begun to feel the effects of climate change. The unprecedented heat dome event of 2021 is just one example that illustrates climate change is happening, and having an impact all around the city and across the region. The City of Terrace (the City) requires locally specific information on how the climate will continue to change as it works to prepare infrastructure and enable citizens to prepare for continued climate change over time. Locally and regionally specific information enables planning for and building resilience over time, by informing planning and decision-making, and influencing resource allocation decisions across sectors. The City has commissioned the Pacific Climate Impacts Consortium (PCIC) to prepare a comprehensive assessment of regional climate change for Terrace and has engaged Pinna Sustainability professionals to assist with conveying this assessment into a summary that can be used to plan and adapt to the changes ahead. This assessment provides information derived from global climate models on projected temperature and precipitation (rain and snow) in the coming decades. It gives us important insight into how these changes will differ by season, and by future time period (the 2050s and 2080s), and also offers information on expected changes in future weather extremes.