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

    This issue of the PCIC Update covers the following stories: Atmospheric River Brings Heavy Rains and Flooding to BC, PCIC Responds to Media Requests Regarding Recent Flooding, Comparing Climate Model Projections Across Canada, Modelling the Temperature of the Nechako, and Transportation Module on ClimateData.ca. The Pacific Climate Seminar Series Talks discussed in this issue are the past talk by Dr. Qiaohong Sun and the upcoming talk by Dr. Ted Shepherd. The staff profile in this issue is on James Hiebert.

  • Source Publication: Progress in Oceanography, 198, 102659. doi:10.1016/j.pocean.2021.102659 Authors: Heneghan, R. F. et al. (T.C. Tai is 21st coauthor) Publication Date: Oct 2021

    Climate change is warming the ocean and impacting lower trophic level (LTL) organisms. Marine ecosystem models can provide estimates of how these changes will propagate to larger animals and impact societal services such as fisheries, but at present these estimates vary widely. A better understanding of what drives this inter-model variation will improve our ability to project fisheries and other ecosystem services into the future, while also helping to identify uncertainties in process understanding. Here, we explore the mechanisms that underlie the diversity of responses to changes in temperature and LTLs in eight global marine ecosystem models from the Fisheries and Marine Ecosystem Model Intercomparison Project (FishMIP). Temperature and LTL impacts on total consumer biomass and ecosystem structure (defined as the relative change of small and large organism biomass) were isolated using a comparative experimental protocol. Total model biomass varied between −35% to +3% in response to warming, and -17% to +15% in response to LTL changes. There was little consensus about the spatial redistribution of biomass or changes in the balance between small and large organisms (ecosystem structure) in response to warming, an LTL impacts on total consumer biomass varied depending on the choice of LTL forcing terms. Overall, climate change impacts on consumer biomass and ecosystem structure are well approximated by the sum of temperature and LTL impacts, indicating an absence of nonlinear interaction between the models’ drivers. Our results highlight a lack of theoretical clarity about how to represent fundamental ecological mechanisms, most importantly how temperature impacts scale from individual to ecosystem level, and the need to better understand the two-way coupling between LTL organisms and consumers. We finish by identifying future research needs to strengthen global marine ecosystem modelling and improve projections of climate change impacts.

  • Source Publication: Science Advances, 7, eabh0895 Authors: Cheung, W. W. L., T.L. Frölicher, V.W.Y. Lam, M. Oyinlola, G. Reygondeau, U.R. Sumaila, T.C. Tai, L.C.L Teh and C.C.C. Wabnitz Publication Date: Oct 2021

    Extreme temperature events have occurred in all ocean basins in the past two decades with detrimental impacts on marine biodiversity, ecosystem functions, and services. However, global impacts of temperature extremes on fish stocks, fisheries, and dependent people have not been quantified. Using an integrated climate-biodiversity-fisheries-economic impact model, we project that, on average, when an annual high temperature extreme occurs in an exclusive economic zone, 77% of exploited fishes and invertebrates therein will decrease in biomass while maximum catch potential will drop by 6%, adding to the decadal-scale mean impacts under climate change. The net negative impacts of high temperature extremes on fish stocks are projected to cause losses in fisheries revenues and livelihoods in most maritime countries, creating shocks to fisheries social-ecological systems particularly in climate-vulnerable areas. Our study highlights the need for rapid adaptation responses to extreme temperatures in addition to carbon mitigation to support sustainable ocean development.

  • Source Publication: Weather and Climate Extremes, 34, 100388, doi:10.1016/j.wace.2021.100388. Authors: Ben Alaya, M.A., F.W. Zwiers and X. Zhang Publication Date: Oct 2021

    The uniform risk engineering practices that are increasingly being adopted for structural design require estimates of the extreme wind loads with very low annual probabilities of exceedance, corresponding to return periods of up to 3000-years in some cases. These estimates are necessarily based on observational wind data that typically spans only a few decades. The estimates are therefore affected by both large sampling uncertainty and, potentially, non-negligible biases. Design practices that aim to meet mandated structural reliability criteria take the sampling uncertainty of long period wind speed or wind pressure estimates into account, but reliability could be compromised if estimates are also biased. In many circumstances, estimates are obtained by fitting an extreme value distribution to annual maximum wind speed observed over a few decades. A key assumption implicit in doing so is that wind speed annual maxima are max-stable. Departures from max-stability can exacerbate the uncertainty of long-period return level estimates by inducing systematic estimation bias as well. Observational records, however, are generally too short to assess max-stability. We therefore use wind speed data from a large (50-member) ensemble of CanRCM4 historical simulations over North America to assess whether wind speed annual maxima are max-stable. While results are generally reassuring at the continental scale, disquieting evidence of a lack of max-stability is often found in the central and southern parts of the continent. Results show that when annual maximum wind speeds are not max-stable, long period return level extreme wind speeds tend to be underestimated, which would compromise reliability if used to design infrastructure such as tall buildings and towers.

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

    This is the Pacific Climate Impacts Consortium's 2020-2021 Corporate Report.

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

    This issue of the PCIC Update containts the following stories: Assessing Changing Flood Risk, Congratulations to the Recipients of the 2021 Nobel Prize in Physics, 2020-2021 Corporate Report Released, Supporting the Management of BC Salmon Habitats, Talks at the Pacific Climate Seminar Series. The staff profile is on Dr. Dhouha Ouali.

  • Source Publication: Ecology Letters, doi:10.1111/ele.13866 Authors: Florko, K. R. N., T.C. Tai, W.W.L. Cheung, S.H. Ferguson, U.R. Sumaila, D.J. Yurkowski and M. Auger-Méthé Publication Date: Oct 2021

    Arctic sea ice loss has direct consequences for predators. Climate-driven distribution shifts of native and invasive prey species may exacerbate these consequences. We assessed potential changes by modelling the prey base of a widely distributed Arctic predator (ringed seal; Pusa hispida) in a sentinel area for change (Hudson Bay) under high- and low-greenhouse gas emission scenarios from 1950 to 2100. All changes were relatively negligible under the low-emission scenario, but under the high-emission scenario, we projected a 50% decline in the abundance of the well-distributed, ice-adapted and energy-rich Arctic cod (Boreogadus saida) and an increase in the abundance of smaller temperate-associated fish in southern and coastal areas. Furthermore, our model predicted that all fish species declined in mean body size, but a 29% increase in total prey biomass. Declines in energy-rich prey and restrictions in their spatial range are likely to have cascading effects on Arctic predators.

  • Source Publication: Weather and Climate Extremes, 33, 100332, doi:10.1016/j.wace.2021.100332 Authors: Huang, W.K., A.H. Monahan and F.W. Zwiers Publication Date: Aug 2021

    Simultaneous concurrence of extreme values across multiple climate variables can result in large societal and environmental impacts. Therefore, there is growing interest in understanding these concurrent extremes. In many applications, not only the frequency but also the magnitude of concurrent extremes are of interest. One way to approach this problem is to study the distribution of one climate variable given that another is extreme. In this work we develop a statistical framework for estimating bivariate concurrent extremes via a conditional approach, where univariate extreme value modeling is combined with dependence modeling of the conditional tail distribution using techniques from quantile regression and extreme value analysis to quantify concurrent extremes. We focus on the distribution of daily wind speed conditioned on daily precipitation taking its seasonal maximum. The Canadian Regional Climate Model large ensemble is used to assess the performance of the proposed framework both via a simulation study with specified dependence structure and via an analysis of the climate model-simulated dependence structure.

  • Source Publication: Hydrological Processes, 35, 7, e14253, doi:10.1002/hyp.14253 Authors: Tsuruta, K. and M.A. Schnorbus Publication Date: Aug 2021

    The mountainous watersheds of western Canada are generally thought to be in a state of transition from snow-dominated to hybrid regimes. In stream networks that are regulated, the effects of this transition on streamflow can have compelling operational consequences. Seasonal magnitude changes may impact spill-risk management, while changes in the composition of summer runoff may increase its variability and reduce the forecasting capabilities of state variables like peak snow water equivalent. Though glacier loss can have a considerable impact on summer runoff, few studies explicitly model the ongoing glacier recession in conjunction with other primary hydrological processes. In this study, we incorporate glacier dynamics from a previous run of the Regional Glaciation Model into the University of British Columbia Watershed Model via the Raven modelling framework. We use this modelling system to explore potential changes under Representative Concentration Pathways 4.5 and 8.5 to the hydrology of the ∼20000km2 Mica Basin, a regulated watershed containing the headwaters of the Columbia River. Our results project statistically significant increases in spring flow in future eras, which may force lower reservoir drafting in late winter, creating potential for energy shortfalls in early spring. We project the coefficient of variation of summer runoff generally goes unchanged in future eras as does the summer runoff forecasting capability of April 1st SWE. Hence, despite modelled glacier loss and reduced snowmelt contribution, our study does not reject the null hypothesis that the predictability of the Mica Basin's summer runoff is unchanged in future eras. We explore these results in detail because they superficially appear to contrast the conventional conceptualization that reduced snowmelt negatively affects the predictive powers of snowpack and glacier loss increases the variability of runoff. We argue that our results' apparent discordance from convention displays the complexities inherent in isolating the effects of changes to a single water balance component when other components are also non-stationary and highlights the benefits of using modelling to more explicitly explore such implications.

  • Source Publication: Scientific Reports, 11, 13574, doi:10.1038/s41598-021-92920-7 Authors: Meshesha, T.W., J. Wang and N.D. Melaku Publication Date: Aug 2021

    Groundwater is a vital resource for human welfare. However, due to various factors, groundwater pollution is one of the main environmental concerns. Yet, it is challenging to simulate groundwater quality dynamics due to the insufficient representation of nutrient percolation processes in the soil and Water Assessment Tool model. The objectives of this study were extending the SWAT module to predict groundwater quality. The results proved a linear relationship between observed and calculated groundwater quality with coefficient of determination (R2), Nash-Sutcliffe efficiency (NSE), percent bias (PBIAS) values in the satisfied ranges. While the values of R2, NSE and PBIAS were 0.69, 0.65, and 2.68 during nitrate calibration, they were 0.85, 0.85 and 5.44, respectively during nitrate validation. Whereas the values of R2, NSE and PBIAS were 0.59, 0.37, and - 2.21 during total dissolved solid (TDS) calibration and they were 0.81, 0.80, 7.5 during the validation. The results showed that the nitrate and TDS concentrations in groundwater might change with varying surface water quality. This indicated the requirement for designing adaptive management scenarios. Hence, the extended SWAT model could be a powerful tool for future regional to global scale modelling of nutrient loads and effective surface and groundwater management.

  • Source Publication: Frontiers in Marine Science, 8, 596644, doi: doi:10.3389/fmars.2021.596644 Authors: Tai T.C., U.R. Sumaila and W.W.L. Cheung, 2021 Publication Date: Aug 2021

    Elevated atmospheric carbon dioxide (CO2) is causing global ocean changes and drives changes in organism physiology, life-history traits, and population dynamics of natural marine resources. However, our knowledge of the mechanisms and consequences of ocean acidification (OA) – in combination with other climatic drivers (i.e., warming, deoxygenation) – on organisms and downstream effects on marine fisheries is limited. Here, we explored how the direct effects of multiple changes in ocean conditions on organism aerobic performance scales up to spatial impacts on fisheries catch of 210 commercially exploited marine invertebrates, known to be susceptible to OA. Under the highest CO2 trajectory, we show that global fisheries catch potential declines by as much as 12% by the year 2100 relative to present, of which 3.4% was attributed to OA. Moreover, OA effects are exacerbated in regions with greater changes in pH (e.g., West Arctic basin), but are reduced in tropical areas where the effects of ocean warming and deoxygenation are more pronounced (e.g., Indo-Pacific). Our results enhance our knowledge on multi-stressor effects on marine resources and how they can be scaled from physiology to population dynamics. Furthermore, it underscores variability of responses to OA and identifies vulnerable regions and species.

  • Source Publication: Geophysical Research Letters, 48, 9, e2021GL092831, doi:10.1029/2021GL092831 Authors: Wang, J., C. Li, F. Zwiers, X. Zhang, G. Li, Z. Jiang, P. Zhai, Y. Sun, Z. Li and Q. Yue Publication Date: Aug 2021

    Field significance tests have been widely used to detect climate change. In most cases, a local test is used to identify significant changes at individual locations, which is then followed by a field significance test that considers the number of locations in a region with locally significant changes. The choice of local test can affect the result, potentially leading to conflicting assessments of the impact of climate change on a region. We demonstrate that when considering changes in the annual extremes of daily precipitation, the simple Mann-Kendall trend test is preferred as the local test over more complex likelihood ratio tests that compare the fits of stationary and nonstationary generalized extreme value distributions. This lesson allows us to report, with enhanced confidence, that the intensification of annual extremes of daily precipitation in China since 1961 became field significant much earlier than previously reported.

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

    This issue of the PCIC Update containts the following stories: PCIC Responds to the Extreme Heat Wave, New IPCC Assessment Report Released, Evaluating the Latest Climate Model Results, Collaborating with Forest Ecolobists to Improve BC Climate Mapping, New PCIC Science Brief: Should the RCP 8.5 Emissions Scenario Represent "Business as Usual"? The staff profile is on Dr. Qiaohong Sun.

  • Source Publication: Frontiers in Marine Science, 8, 1–12. doi:10.3389/fmars.2021.596644 Authors: Tai, T. C., U.R. Sumaila, and W.W.L. Cheung Publication Date: Jul 2021

    Elevated atmospheric carbon dioxide (CO2) is causing global ocean changes and drives changes in organism physiology, life-history traits, and population dynamics of natural marine resources. However, our knowledge of the mechanisms and consequences of ocean acidification (OA) – in combination with other climatic drivers (i.e., warming, deoxygenation) – on organisms and downstream effects on marine fisheries is limited. Here, we explored how the direct effects of multiple changes in ocean conditions on organism aerobic performance scales up to spatial impacts on fisheries catch of 210 commercially exploited marine invertebrates, known to be susceptible to OA. Under the highest CO2 trajectory, we show that global fisheries catch potential declines by as much as 12% by the year 2100 relative to present, of which 3.4% was attributed to OA. Moreover, OA effects are exacerbated in regions with greater changes in pH (e.g., West Arctic basin), but are reduced in tropical areas where the effects of ocean warming and deoxygenation are more pronounced (e.g., Indo-Pacific). Our results enhance our knowledge on multi-stressor effects on marine resources and how they can be scaled from physiology to population dynamics. Furthermore, it underscores variability of responses to OA and identifies vulnerable regions and species.

  • 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: Schoeneberg, A.T., Q. Sun and M.A. Schnorbus Publication Date: Mar 2021

    Pilot study for the development of stream flow design value projections and a prototype online tool. The BC Ministry of Transportation and Infrastructure supported PCIC in a pilot project to quantify design flood values (2-, 20-, 50-, 100- and 200-year events) for historical and future periods and make them accessible as a gridded product via PCIC’s Climate Explorer tool. As part of this work, PCIC has also been asked to calculate and supply the Melton Ratio as a gridded product. This study focuses on the Upper Fraser, a 34,200 km2 region upstream of Prince George, BC, with primarily snow-dominated watersheds. This report was prepared for the Engineering Services Branch of the Engineering Systems Department of the Highway Services Department, Ministry of Transportation and Infrastructure, Government of British Columbia.

  • 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.

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