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  • Authors: Philip, S.Y. et al. (F. Anslow is sixth author) Publication Date: Jul 2021

    Main findings: Based on observations and modeling, the occurrence of a heatwave with maximum daily temperatures (TXx) as observed in the area 45–52 ºN, 119–123 ºW, was virtually impossible without human-caused climate change. The observed temperatures were so extreme that they lie far outside the range of historically observed temperatures. This makes it hard to quantify with confidence how rare the event was. In the most realistic statistical analysis the event is estimated to be about a 1 in 1000 year event in today’s climate.There are two possible sources of this extreme jump in peak temperatures. The first is that this is a very low probability event, even in the current climate which already includes about 1.2°C of global warming -- the statistical equivalent of really bad luck, albeit aggravated by climate change. The second option is that nonlinear interactions in the climate have substantially increased the probability of such extreme heat, much beyond the gradual increase in heat extremes that has been observed up to now. We need to investigate the second possibility further, although we note the climate models do not show it. All numbers below assume that the heatwave was a very low probability event that was not caused by new nonlinearities. With this assumption and combining the results from the analysis of climate models and weather observations, an event, defined as daily maximum temperatures (TXx) in the heatwave region, as rare as 1 in a 1000 years would have been at least 150 times rarer without human-induced climate change. Also, this heatwave was about 2°C hotter than it would have been if it had occurred at the beginning of the industrial revolution (when global mean temperatures were 1.2°C cooler than today). Looking into the future, in a world with 2°C of global warming (0.8°C warmer than today which at current emission levels would be reached as early as the 2040s ), this event would have been another degree hotter. An event like this -- currently estimated to occur only once every 1000 years, would occur roughly every 5 to 10 years in that future world with 2°C of global warming.

  • Authors: Schoeneberg, A.T. and M.A. Schnorbus Publication Date: Jun 2021

    This PCIC report demonstrates an analysis of projected changes in three streamflow metrics that are of interest to decision makers. Changes in low, mean and high daily streamflow in the 2020s, 2050s and 2080s were analyzed in three select watersheds using PCIC’s CMIP5 hydrologic model results. This report was enabled with financial support from FLNRORD/ENV that is gratefully acknowledged, and draws on hydrologic modelling that PCIC has recently undertaken with support from BC Hydro, its own core resources, and Compute Canada. The report is a potential starting point for dialogue between PCIC and water managers that would allow both parties to learn more about each other’s needs and capabilities.

  • Authors: The Pacific Climate Impacts Consortium Publication Date: Jun 2021

    The state of the future climate depends on human actions, primarily the emission of greenhouse gases and other industrial pollutants. This raises the questions: "What path are recent historical emissions following?" "What path would we be on, if we continue with business-as-usual, in the absence of further mitigation action?" And, "Are these paths reliable guides to future emissions?" One scenario that is commonly used in the scientific literature, RCP 8.5, is often referred to as "business-as-usual." Recently, some scientists have taken issue with this description, saying it is unrealistic and may hinder the goal of emissions reductions policy. Others argue that, in fact, RCP 8.5 is the scenario that most closely tracks cumulative emissions to date, that it is thus of the most use for planning out to the middle of the century. In this Science Brief, we unpack each of these arguments and evaluate what these differing perspectives can tell us about the ultimate objective of emissions scenarios as tools for exploring future climate change.

  • Source Publication: Journal of Climate, 34, 9, 3441-3460, doi:10.1175/JCLI-D-19-1013.1. Authors: Li, C., F. Zwiers, X. Zhang, G. Li, Y. Sun and M. Wehner Publication Date: May 2021

    This study presents an analysis of daily temperature and precipitation extremes with return periods ranging from 2 to 50 years in phase 6 of the Coupled Model Intercomparison Project (CMIP6) multimodel ensemble of simulations. Judged by similarity with reanalyses, the new-generation models simulate the present-day temperature and precipitation extremes reasonably well. In line with previous CMIP simulations, the new simulations continue to project a large-scale picture of more frequent and more intense hot temperature extremes and precipitation extremes and vanishing cold extremes under continued global warming. Changes in temperature extremes outpace changes in global annual mean surface air temperature (GSAT) over most landmasses, while changes in precipitation extremes follow changes in GSAT globally at roughly the Clausius–Clapeyron rate of ~7% °C−1. Changes in temperature and precipitation extremes normalized with respect to GSAT do not depend strongly on the choice of forcing scenario or model climate sensitivity, and do not vary strongly over time, but with notable regional variations. Over the majority of land regions, the projected intensity increases and relative frequency increases tend to be larger for more extreme hot temperature and precipitation events than for weaker events. To obtain robust estimates of these changes at local scales, large initial-condition ensemble simulations are needed. Appropriate spatial pooling of data from neighboring grid cells within individual simulations can, to some extent, reduce the needed ensemble size.

  • Authors: The Pacific Climate Impacts Consortium Publication Date: Mar 2021

    The March 2021 issue of the PCIC Update newsletter covers the following stories: 2020: A Year in Review, Two New Birds Join the DACCS Birdhouse, New Climate-Resilient Buildings and Core Infrastructure Report, Upcoming Talk in the Pacific Climate Seminar Series, Report on Wind and Power Outages Released, and Introducing ClimateWest. The staff profile is on PCIC Climate Data Analyst, Charlotte Ballantyne.

  • Source Publication: Climatic Change 165, 14, doi: 10.1007/s10584-021-03037-9 Authors: Mahmoudi, M.H., M.R. Najafi, H. Singh and M. Schnorbus Publication Date: Mar 2021

    Increases in the intensity and frequency of hydroclimatic extremes associated with climate change can cause significant socioeconomic problems. Assessments of projected extremes using only a limited number of general circulation model (GCM) simulations can undermine the capacity to differentiate and communicate the contribution of internal climate variability (ICV) and external forcing and result in an underestimation of associated risks. In this study, we assess the impacts of climate change on extreme temperature and precipitation and quantify the contribution of internal variability over the Columbia, Fraser, Peace and Campbell River basins in northwestern North America (NWNA). Seven GCMs that participated in the Coupled Model Intercomparison Project Phase 5 (CMIP5) and a large ensemble of CanESM2 model simulations (50 members) are downscaled to 1/16° spatial resolution using Bias Correction Constructed Analogues with Quantile mapping reordering version 2 (BCCAQ2). Spatial and temporal changes of climate extreme indices, representing the frequency and intensity of extreme temperature and precipitation, are assessed over the historical (1981–2010) and future (2060–2089) periods under the Representative Concentration Pathway (RCP) 8.5. The influence of ICV on the estimated trends of extreme indices is characterised. Overall, both the frequency and intensity of extreme temperature and precipitation events are projected to increase in NWNA indicating more severe dry days and wet conditions in the future. High-elevation Rocky and the Coast Mountains are at larger risks of extreme precipitation, while the Columbia basin, which already faces drought issues, is expected to experience severe dry conditions. Internal climate variability plays a significant role, particularly in the trends of precipitation-related indices. The signal to internal noise ratio analyses suggest that higher elevations experience stronger forcing signals for precipitation-based indices compared to the other regions.

  • Authors: Yanping He, Francis Zwiers and Nguyen Quoc Publication Date: Mar 2021

    Relationships among surface wind speed, North Pacific climate variability, Pacific climate variability, and tree/weather related power outages are investigated in forest rich British Columbia using almost 12 years of BC Hydro (BCH) wind and power outage data, two decades of BC weather station observations and two climate variability indices. Strong surface wind is found to be the dominate cause of power outages that are reported as being tree or weather related. The observed regional fraction of power outage days and the number of influenced customers per outage day increases quickly when the daily maximum wind speed (DMWS) exceeds 50 km/hr. These extreme winds are mostly observed during winter, with substantial interannual variability in BC coastal regions in the frequency of strong days when DMWS exceeds 50 km/hr. A simple empirical outage model is developed using monthly DMWS frequency in southern coastal BC as a predictor. Cross-validation, which is used to estimate the model's out-of-sample performance, suggests a useful level of skill in hindcasting subseasonal to interannual variations in the frequency of observed regional tree/weather outage occurrence during the 2005 to 2017 period when power outage data are available. The widespread power outage event of December 2006 can also be captured when winter windstorm information is added as an additional model input.

  • Authors: The Pacific Climate Impacts Consortium Publication Date: Feb 2021

    This Science Brief covers a paper in the Proceedings of the National Academy of Sciences, by Xu et al. (2020), who use global climate model (GCM) output, weather station data, estimates of historical global population density, and data on global gross domestic product (GDP), crop and livestock production, to determine if there has been a human climate niche. They determine that such a niche has existed. For the past 6000 years, human populations have lived largely in a fairly narrow range of climates and populations clustered around two temperature ranges, with most people living in a range of about 11°C to about 15°C for mean annual temperature and a smaller, but significant portion living in a range around 20°C to about 25°C.
    They then examine how this niche may change in the future. They find that, under a high emissions scenario, this niche is projected to shift spatially more in the upcoming 50 years than it has in the past 6000, leaving a third of the projected future human population in regions where the mean annual temperature is greater than 29°C.

  • Authors: Environment and Climate Change Canada’s Climate Research Division, PCIC and the National Research Council Publication Date: Jan 2021

    This report provides an assessment of how climatic design data relevant to the National Building Code of Canada and the Canadian Highway Bridge Design Code might change as the climate continues to warm.

  • Authors: The Pacific Climate Impacts Consortium Publication Date: Jan 2021

    The January 2021 edition of the PCIC Update contains the following articles: Supporting Water Planning in BC, Developing Risk Assessment Tools for Salmon Habitat Management, and Engaging with the Agricultural Community. The staff profile is a joint one, highlighting the contributions of Jessie Booker and Cairo Sanders. It also contains PCIC staff news and publications.

  • Source Publication: Weather and Climate Extremes,30, 100290, doi:10.1016/j.wace.2020.100290 Authors: Ben Alaya, M.A., F.W. Zwiers and X. Zhang Publication Date: Dec 2020

    We describe in this paper a semi-parametric bivariate extreme value approach for studying rare extreme precipitation events considered as events that result from a combination of extreme precipitable water (PW) in the atmospheric column above the location where the event occurred and extreme precipitation efficiency, described as the ratio between precipitation and PW. An application of this framework to historical 6-h precipitation accumulations simulated by the Canadian Regional Climate Model CanRCM4 shows that uncertainties and biases of very long-period return level estimates can be substantially reduced relative to the standard univariate approach that fits Generalized Extreme Value distributions to samples of annual maxima of extreme precipitation even when using modest amounts of data.

  • Authors: The Pacific Climate Impacts Consortium Publication Date: Nov 2020

    This is PCIC's Corporate Report for 2019-2020.

  • Authors: The Pacific Climate Impacts Consortium Publication Date: Nov 2020

    This is the November 2020 issue of the PCIC Update. It includes the following stories: A Preview of Winter? A Record Wet and Cool Spring and Summer in BC; Studying how Changing Precipitation May Affect Landslides in BC; Supporting BC Salmon Management; PCIC Corporate Report Released and Vancouver Island Agriculture Planning Report Released. This issue's staff profile is on Dr. Md. Shahabul Alam. The issue concludes with the PCIC staff news and a list of recent publications by PCIC researchers.

  • Source Publication: Journal of Climate, advanced online view, doi: 10.1175/JCLI-D-19-0892.1. Authors: Sun, Q., X. Zhang, F. W. Zwiers, S. Westra, and L.V. Alexander Publication Date: Sep 2020

    This paper provides an updated analysis of observed changes in extreme precipitation using high quality station data up to 2018. We examine changes in extreme precipitation represented by annual maxima of one day (Rx1day) and five-day (Rx5day) precipitation accumulations at different spatial scales and attempt to address whether the signal in extreme precipitation has strengthened with several years of additional observations. Extreme precipitation has increased at about two thirds of stations and the percentage of stations with significantly increasing trends is significantly larger than that can be expected by chance for the globe, continents including Asia, Europe, and North America, and regions including C. North-America, E. North-America, N. Central-America, N. Europe, Russian-Far-East, E.C. Asia, and E. Asia. The percentage of stations with significantly decreasing trends is not different from that expected by chance. Fitting extreme precipitation to generalized extreme value distributions with global mean surface temperature (GMST) as a co-variate reaffirms the statistically significant connections between extreme precipitation and temperature. The global median sensitivity, percent change in extreme precipitation per Kelvin increase in GMST is 6.6% (5.1 to 8.2%, 5–95% confidence interval) for Rx1day and is slightly smaller at 5.7% (5.0 to 8.0%) for Rx5day. The comparison of results based on observations ending in 2018 with those from data ending in 2000–2009 shows a consistent median rate of increase, but a larger percentage of stations with statistically significant increasing trends, indicating an increase in the detectability of extreme precipitation intensification, likely due to the use of longer records.

  • Authors: The Pacific Climate Impacts Consortium Publication Date: Aug 2020

    This report places the conditions in British Columbia (BC) over 2019 into climatological context. It finds that: a moderate El Niño likely contributed to a slightly warmer than normal 2019 in BC; anomalous warmth peaked in spring, forcing rapid melt of a near-normal winter snowpack; precipitation in summer and fall was above-to-much-above normal across the province; trends in temperature are positive for the period 1950 – 2019 with minimum temperatures (Tmin) increasing faster than maximum temperatures (Tmax), and that precipitation shows no significant trend over the same period.

  • Source Publication: Journal of Climate, 33, 16, 6957–6970, doi:10.1175/JCLI-D-19-0011.1 Authors: Ben Alaya, M.A., F.W. Zwiers and X. Zhang Publication Date: Aug 2020

    The recurring devastation caused by extreme events underscores the need for reliable estimates of their intensity and frequency. Operational frequency and intensity estimates are very often obtained from generalized extreme value (GEV) distributions fitted to samples of annual maxima. GEV distributed random variables are “max-stable,” meaning that the maximum of a sample of several values drawn from a given GEV distribution is again GEV distributed with the same shape parameter. Long-period return value estimation relies on this property of the distribution. The data to which the models are fitted may not, however, be max-stable. Observational records are generally too short to assess whether max-stability holds in the upper tail of the observations. Large ensemble climate simulations, from which we can obtain very large samples of annual extremes, provide an opportunity to assess whether max-stability holds in a model-simulated climate and to quantify the impact of the lack of max-stability on very long period return-level estimates. We use a recent large ensemble simulation of the North American climate for this purpose. We find that the annual maxima of short-duration precipitation extremes tend not to be max-stable in the simulated climate, as indicated by systematic variation in the estimated shape parameter as block length is increased from 1 to 20 years. We explore how the lack of max-stability affects the estimation of very long period return levels and discuss reasons why short-duration precipitation extremes may not be max-stable.

  • Source Publication: Science of The Total Environment, 728, 138808, doi:0.1016/j.scitotenv.2020.138808 Authors: Brubacher, J., D.M. Allen, S.J. Déry, M.W. Parkes, B. Chhetri, S. Mak, S. Sobie and T.K. Takaro Publication Date: Aug 2020

    Background 
    Food- and water-borne pathogens exhibit spatial heterogeneity, but attribution to specific environmental processes is lacking while anthropogenic climate change alters these processes. The goal of this study was to investigate ecology, land-use and health associations of these pathogens and to make future disease projections. 

    Methods
    The rates of five acute gastrointestinal illnesses (AGIs) (campylobacteriosis, Verotoxin- producing Escherichia coli, salmonellosis, giardiasis and cryptosporidiosis) from 2000 to 2013 in British Columbia, Canada, were calculated across three environmental variables: ecological zone, land use, and aquifer type. A correlation analysis investigated relationships between 19 climatic factors and AGI. Mean annual temperature at the ecological zone scale was used in a univariate regression model to calculate annual relative AGI risk per 1 °C increase. Future cases attributable to climate change were estimated into the 2080s.

    Findings
    Each of the bacterial AGI rates was correlated with several annual temperature-related factors while the protozoan AGIs were not. In the regression model, combined relative risk for the three bacterial AGIs was 1.1 [95% CI: 1.02–1.21] for every 1 °C in mean annual temperature. Campylobacteriosis, salmonellosis and giardiasis rates were significantly higher (p < 0.05) in the urban land use class than in the rural one. In rural areas, bacteria and protozoan AGIs had significantly higher rates in the unconsolidated aquifers. Verotoxin-producing Escherichia coli rates were significantly higher in watersheds with more agricultural land, while rates of campylobacteriosis, salmonellosis and giardiasis were significantly lower in agricultural watersheds. Ecological zones with higher bacterial AGI rates were generally projected to expand in range by the 2080s.

    Interpretation
    These findings suggest that risk of AGI can vary across ecosystem, land use and aquifer type, and that warming temperatures may be associated with an increased risk of food-borne AGI. In addition, spatial patterns of these diseases are projected to shift under climate change.

  • Source Publication: Journal of Hydrology, 587, 124939, doi:10.1016/j.jhydrol.2020.124939 Authors: Melaku, N.D., J. Wang and T.W. Meshesha Publication Date: Aug 2020

    Peatlands cover only about 3% of the Earth’s surface and store 15–30% of the Global soil carbon as a peat. However, human intervention and climate change threatens the stability of peatlands, owing to deforest, wildfire, mining, drainage, glacial retreat, and permafrost. In our study, we modified the SWAT model to couple snow, soil temperature and carbon dioxide emission. Then the modified SWAT was used for predicting snow depth, soil temperature at different depths and carbon dioxide emission from peatlands and other land uses at Athabasca river basin, Canada. The results of the study indicated that SWAT model estimated the daily snow depth with R2, NSE, RMSE and PBIAS values of 0.83, 0.76, 0.52 and −2.3 in the calibration period (2006–2007) and 0.79, 0.71, 0.97 and −3.6 for the validation period (2008–2009), respectively. The SWAT model also predicted soil temperature very well at three depths (5 cm, 10 cm and 30 cm). The simulation model results also confirmed that the modified SWAT model estimates the CO2 emission at Athabasca river basin with good model fit during calibration (R2 = 0.71, NSE = 0.67, RMSE = 2.6 and PBIAS = 3.2) and during validation (R2 = 0.63, NSE = 0.58, RMSE = 3.1 and PBIAS = 9.3). Overall, our result confirmed that SWAT model performed well in representing the dynamics of snow depth, soil temperature and CO2 emissions in the peatlands at the Athabasca river basin.

  • Source Publication: Journal of Hydrology, 587, 124952, doi:10.1016/j.jhydrol.2020.124952 Authors: Meshesha, T.W., J. Wang and N.D. Melaku Publication Date: Aug 2020

    Cold climate regions offer various ecosystem services. The water quality parameters such as dissolved oxygen (DO), water temperature (Tw), and dissolved organic carbon (DOC) have considerable impacts on the aquatic ecosystem species. Any impairments in water quality such as elevated water temperature, and low DO concentrations can limit the survival of aquatic ecosystems and its species, such as walleye, northern pike and salmon. Therefore, a good understanding of the aquatic ecosystem of rivers is essential for effective and sustainable river basin and watershed management of fisheries and aquatic resources. The objectives of this study is to improve a watershed scale module of water quality (DO, DOC and Fecal coliforms (FC) in the SWAT model to examine the spatiotemporal patterns and their impacts on aquatic ecosystem and water quality processes in the Athabasca River Basin (ARB), Alberta, Canada. The calibration and validation results of DO, DOC and FC show that the improved Soil and Water Assessment Tool (SWAT) model achieved successfully with a varied range (satisfactory to vey-good) of accuracy at the daily temporal scales. The results showed that concentrations of DO for the selected stations (spring and summer) reduced far below the thresholds for ecosystems survival. In concurrent reduction with DO, the FC concentration considerably varied in the different monitoring stations of ARB. These results highlight that DO, DOC and FC variability in the ARB may drive changes in water quality and ecosystem services that have to be understood on the specific research scale for designing adaptive management scenarios. This study reveals that the new SWAT model can be applied to other similar regions of the worlds.

  • Authors: The Pacific Climate Impacts Consortium Publication Date: Aug 2020

    The August 2020 edition of the PCIC Update covers the following stories: the release of the 2019 in BC, in Climatological Context report; the New Plan2Adapt tool; and the Survey on Future Climate Data and Information Needs in the Building Sector. The staff profile is on Dr. Charles Curry. The Update covers a number of webinars, with BC ACARN, FPInnovations and those talks given by PCIC researchers at the 54th Annual CMOS Congress. The Update also included PCIC staff news and recent publications.

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