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  • Source Publication: Science China Earth Sciences, 66, 2125–2141, doi:10.1007/s11430-022-1154-7 Authors: Zhu, H., Z. Jiang, L. Li, W. Li, S. Jiang, P. Zhou, W. Zhao and T. Li Publication Date: Jun 2023

    Climate 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.

  • Authors: The Pacific Climate Impacts Consortium Publication Date: Jun 2023

    This Science Brief covers a paper published in Nature Climate Change that uses reanalysis data to examine extreme fire weather and the conditions that drive it over the 1979-2020 period. The paper shows that temperature and relative humidity are driving observed global trends of increased fire weather. In this Science Brief we discuss what these results tell us about changes to fire weather in our province and across Canada.

  • Authors: The Pacific Climate Impacts Consortium Publication Date: Jun 2023

    This issue of the PCIC Update contains the following stories: Climate Projections for the City of Terrace Released and A Mystery Gremlin Resolved! It also contains an update on the Pacific Climate Seminar Series, staff changes at PCIC and PCIC's most recent publications. The staff profile in this issue is on Tom Kunkel.

  • Source Publication: Environmental Modelling & Software, 163, 105682, doi:10.1016/j.envsoft.2023.105682 Authors: Souaissi, Z, T.B. Ouarda, A. St-Hilaire and D. Ouali Publication Date: Jun 2023

    Highlights:
    Improve the estimation of water temperature extremes at ungauged sites.
    Incorporate non-linearities in the homogenous region delineation step using NLCCA.
    Consider non-linear models in the whole estimation procedure (NLCCA + GAM).
    Compare fully and partially non-linear approaches for water temperature regionalization.
    The results underline the importance of considering the non-linearity of thermal processes.

  • Source Publication: Environmental Science and Technology, 57, 19, 7401–7409, doi:10.1021/acs.est.2c08243 Authors: Lao, I.R., A. Feinberg, and N. Borduas-Dedekind Publication Date: Jun 2023

    Selenium (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.

  • Authors: The Pacific Climate Impacts Consortium Publication Date: Jun 2023

    One of the key uncertainties in climate model simulations has to do with the response of low-lying marine clouds to increasing temperatures. A recent paper in the journal Nature uses a mix of radar, lidar and data from atmospheric probes to test one of the mechanisms by which cloud cover is projected to be reduced under climate change. Their findings show that this mechanism is not evident in the trade wind regions, which suggests that might not occur in nature. This further suggests that the most extreme estimates of the climate's response to greenhouse gas emissions are less likely than earlier research suggests. Here we discuss what these results tell us about changes to the Earth's sensitivity to greenhouse gas emissions and what this may mean for our province.

  • Source Publication: Journal of Climate, 36, 18, 6393-6407, doi:10.1175/JCLI-D-22-0713.1 Authors: Sun, Q. F.W. Zwiers, X. Zhang and Y. Tan Publication Date: Jun 2023

    El Niño–Southern Oscillation (ENSO) has a profound influence on the occurrence of extreme precipitation events at local and regional scales in the present-day climate, and thus it is important to understand how that influence may change under future global warming. We consider this question using the large-ensemble simulations of CESM2, which simulates ENSO well historically. CESM2 projects that the influence of ENSO on extreme precipitation will strengthen further under the SSP3–7.0 scenario in most regions whose extreme precipitation regimes are strongly affected by ENSO in the boreal cold season. Extreme precipitation in the boreal cold season that exceeds historical thresholds is projected to become more common throughout the ENSO cycle. The difference in the intensity of extreme precipitation events that occur under El Niño and La Niña conditions will increase, resulting in “more extreme and more variable hydroclimate extremes.” We also consider the processes that affect the future intensity of extreme precipitation and how it varies with the ENSO cycle by partitioning changes into thermodynamic and dynamic components. The thermodynamic component, which reflects increases in atmospheric moisture content, results in a relatively uniform intensification of ENSO-driven extreme precipitation variation. In contrast, the dynamic component, which reflects changes in vertical motion, produces a strong regional difference in the response to forcing. In some regions, this component amplifies the thermodynamic-induced changes, while in others, it offsets them or even results in reduction in extreme precipitation variation.

  • Authors: City of Terrace, The Pacific Climate Impacts Consortium, Pinna Sustainability Publication Date: May 2023

    The Climate Projections for the City of Terrace report provides projections and impacts analysis for the City of Terrace, BC and is intended to support decision making throughout the region and to help community partners better understand how their work may be affected by the changing climate

  • Authors: The Pacific Climate Impacts Consortium Publication Date: Apr 2023

    This issue of the PCIC Update contains the following stories: Correcting CMIP6 Model Output for Downscaling, Bilingual Design Value Explorer Announcement, and IPCC Summary for Policy Makers on Synthesis Report. It also contains an update on the Pacific Climate Seminar Series, staff changes at PCIC and PCIC's most recent publications. The staff profile in this issue is on Nina Nichols.

  • Source Publication: Journal of Hydrology: Regional Studies, 44, 101237, doi:10.1016/j.ejrh.2022.101237 Authors: Larabi, S., M. A. Schnorbus, and F. Zwiers Publication Date: Dec 2022

    Study region:
    Nechako Reservoir, British Columbia, Canada.

    Study focus:
    Hydrological regulation affect both hydrological and thermal conditions in the reservoir and downstream reach, subsequently disrupting fish habitats. This paper aims at developing an integrated model simulating physical processes that govern the quantity and quality of inflow, reservoir, and outflow water of the Nechako Reservoir. Such a model would help stakeholders understand the response of in-reservoir water temperature stratification and downstream water temperature to changes in inflow and reservoir operation under future climate change.

    New hydrological insights for the region:
    The model was calibrated against historical reservoir levels and in-reservoir and outlet water temperature field data. The integrated model simulated accurately the wide variation of reservoir levels as well as the in-reservoir water temperature at Kenney Dam and the outlet temperature. Sensitivity analysis shows that reservoir water temperature particularly the epilimnion is sensitive to changes in both meteorological and hydrological forcing. Forcing the model with different outflow scenarios shows the weak sensitivity of temperature of water released to outflow rates. Given epilimnion water releases at the spillway, the Summer Temperature Management Program could be inefficient to provide cool water in the Nechako River during the critical period of salmon migration in a warming climate. However, colder water remains available at depth at Kenney Dam to potentially mitigate and better control downstream water temperature.

  • Source Publication: International Journal of Climatology, 42, 10, doi: org/10.1002/joc.7833.8 Authors: Diaconescu, E., H. Sankare, K. Chow, T.Q. Murdock, and A.J. Cannon Publication Date: Dec 2022

    The projected increase in the frequency and intensity of extreme heat events due to climate change means an associated increase in risk of heat-related illnesses and mortality. Public health systems need to be prepared to identify and reduce the susceptibility of vulnerable populations to increased occurrence of heat-related illness and stress. To facilitate this, climate services have begun developing climate change projections for heat-stress indices based on exceedances of thresholds used operationally in meteorological heat warning systems. This task is complicated by the fact that heat-stress indices are generally computed using hourly data whereas climate model outputs are often archived at daily or longer time steps. This study focuses on Humidex, a heat-stress index used in heat alerts issued by the Meteorological Service of Canada. Several potential solutions for computing robust Humidex indices using daily data are examined, including a new approximation method. Indices obtained with the new method are compared with indices obtained using the classic method based on hourly data as well as with other two methods based on average daily values. The new approximation gives good estimations for humidex indices, while the daily-average-value methods present biases with respect to the hourly-value method.

  • Source Publication: Journal of Hydrology X, 17, 100144, doi:10.1016/j.hydroa.2022.100144 Authors: Tsuruta, K. and M. A. Schnorbus Publication Date: Dec 2022

    As glaciers across the world continue to recede, there is a concern that their loss as a fresh water reservoir within mountainous basins will have a negative impact on stream temperatures and downstream water resources. Currently, there are relatively few glacio-hydrological models (GHMs) appropriate to study such phenomena and studies that have used GHMs generally acknowledge the high uncertainty associated with their simulations. Calibration techniques present a particular issue in GHMs as available glacier observations are limited and errors in the glacierized portion of a basin can be compensated by errors in the non-glacierized portion. Using as a study site the Cheakamus Basin in British Columbia, Canada, we 1) present a new, fully-coupled GHM, 2) analyze the effects different calibration techniques have on the model’s summer streamflow projections, and 3) compare the fully-coupled GHM results to projections using a one-way GHM. The calibration techniques studied vary in terms of glacier representation (dynamic/static), and glacier constraint (mass balance/thinning rates/thinning rates and area change). We find projected future climate forcings are sufficiently strong in the Cheakamus Basin so as to generally make the sign and significance of changes to the basin’s hydrology insensitive to the calibration and projection procedures studied. However, the variation among these procedures produces significant changes in the projected magnitude of future hydrological changes and therefore should be carefully considered in studies where precision beyond the sign and significance of change is required. Based on analysis of the variation within each procedure’s set of model outputs, we conclude 1) the two-way GHM has benefits over the one-way model, 2) calibration using dynamic glaciers and a thinning rate constraint is preferable for the new GHM, and 3) there is a need for additional studies on the uncertainties associated with the calibration of glacio-hydrological models.

  • Source Publication: Canadian Journal of Statistics, 50, 4, 1355-1386, doi:10.1002/cjs.11743 Authors: Dean, C.B., A.H. El-Shaarawi, S.R. Esterby, J. Mills-Flemming, R.D. Routledge, S.W. Taylor, D.G. Woolford, J.V. Zidek and F.W. Zwiers Publication Date: Dec 2022

    This article focuses on the importance of collaboration in statistics by Canadian researchers and highlights the contributions that Canadian statisticians have made to many research areas in environmetrics. We provide a discussion about different vehicles that have been developed for collaboration by Canadians in the environmetrics context as well as specific scientific areas that are focused on environmetrics research in Canada including climate science, forestry, and fisheries, which are areas of importance for natural resources in Canada.

  • Source Publication: Earth's Future, 10, doi:10.1029/2022EF002797 Authors: Li, M., C. Li, Z. Jiang, X. Zhang and F.W. Zwiers Publication Date: Dec 2022

    Observations show that summer precipitation in China has undergone pronounced changes, resulting in an enigmatic “north-south drying-wetting” pattern in eastern China that is of great concern for socio-economic development. Scientific consensus on the mechanisms that are responsible for this pattern of change has not yet been achieved. We show that this complex pattern of summer total precipitation trends observed in China since the 1960s is overwhelmingly the result of changes in daily precipitation frequency, rather than being the result of changes in precipitation intensity or the frequency of synoptic circulation patterns favorable to precipitation. Changes in precipitation intensity, which are very likely due to anthropogenic greenhouse gas forcing, contribute a relatively homogeneous wetting tendency across the country while changes due to synoptic circulation change are weak. The changes in daily precipitation frequency that drive the observed patterns of change may be due to aerosols, but improved process understanding will be required to resolve that question and enable reliable projections of regional scale precipitation change in China and elsewhere.

  • Authors: The Pacific Climate Impacts Consortium Publication Date: Dec 2022

    This issue of the PCIC Update contains the following stories: An Unprecedented Warm and Dry Start to Autumn in Southern BC Gives Way to a Cooler Winter Forecast, Continued Refinement of PCIC’s Downscaling Methods, Analysing Climate Change Impacts on the Nechako River and Working With Hydrologic Projections. It also contains an update on the Pacific Climate Seminar Series, staff changes at PCIC and PCIC's most recent publications. The staff profile in this issue is on Dr. Samah Larabi.

  • Source Publication: Earth System Dynamics, 13, 1689–1713, doi:10.5194/esd-13-1689-2022 Authors: Philip, S. Y., S.F. Kew, G.J. van Oldenborgh, F.S. Anslow, S.I. Seneviratne, R. Vautard, D. Coumou, K.L. Ebi, J. Arrighi, R. Singh, M. van Aalst, C. Pereira Marghidan, M. Wehner, W. Yang, S. Li, D.L. Schumacher, M. Hauser, R. Bonnet, L.N. Luu, F. Lehner, Publication Date: Dec 2022

    Towards the end of June 2021, temperature records were broken by several degrees Celsius in several cities in the Pacific Northwest areas of the US and Canada, leading to spikes in sudden deaths and sharp increases in emergency calls and hospital visits for heat-related illnesses. Here we present a multi-model, multi-method attribution analysis to investigate the extent to which human-induced climate change has influenced the probability and intensity of extreme heat waves in this region. Based on observations, modelling and a classical statistical approach, the occurrence of a heat wave defined as the maximum daily temperature (TXx) observed in the area 45–52∘ N, 119–123∘ W, was found to be virtually impossible without human-caused climate change. The observed temperatures were so extreme that they lay far outside the range of historical temperature observations. This makes it hard to state with confidence how rare the event was. Using a statistical analysis that assumes that the heat wave is part of the same distribution as previous heat waves in this region led to a first-order estimation of the event frequency of the order of once in 1000 years under current climate conditions. Using this assumption and combining the results from the analysis of climate models and weather observations, we found that such a heat wave event would be at least 150 times less common without human-induced climate change. Also, this heat wave was about 2 ∘C hotter than a 1-in-1000-year heat wave would have been in 1850–1900, 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), a 1000-year event would be another degree hotter. Our results provide a strong warning: our rapidly warming climate is bringing us into uncharted territory with significant consequences for health, well-being and livelihoods. Adaptation and mitigation are urgently needed to prepare societies for a very different future.

  • Source Publication: Journal of Applied Meteorology and Climatology, 61, 9, 1139-1157. doi:10.1175/JAMC-D-21-0205.1 Authors: Lao, I. R., C. Abraham, E. Wiebe, and A.H. Monahan Publication Date: Dec 2022

    Nocturnal warming events (NWEs) are abrupt interruptions in the typical cooling of surface temperatures at night. Using temperature time series from the high-resolution Vancouver Island School-Based Weather Station Network (VWSN) in British Columbia, Canada, we investigate temporal and spatial characteristics of NWEs. In this coastal region, NWEs are more frequently detected in winter than in summer, with a seasonal shift from slowly warming NWEs dominating the winter months to rapidly warming NWEs dominating the summer months. Slow-warming NWEs are of relatively small amplitude and exhibit slow cooling rates after the temperature peaks. In contrast, fast-warming NWEs have a temperature increase of several kelvins with shorter-duration temperature peaks. The median behavior of these distinct NWE classes at individual stations is similar across the entire set of stations. The spatial synchronicity of NWEs across the VWSN (determined by requiring NWEs at station pairs to occur within given time windows) decreases with distance, including substantial variability at nearby stations that reflects local influences. Fast-warming NWEs are observed to occur either simultaneously across a number of stations or in isolation at one station. Spatial synchronicity values are used to construct undirected networks to investigate spatial connectivity structures of NWEs. We find that, independent of individual seasons or NWE classes, the networks are largely unstructured, with no clear spatial connectivity structures related to local topography or direction.

  • Authors: The Pacific Climate Impacts Consortium Publication Date: Oct 2022

    This is the Pacific Climate Impacts Consortium's 2021-2022 Corporate Report.

  • Authors: Markus Schnorbus Publication Date: Jul 2022

    This report, the first volume in the VIC Generation 2 deployment reports, provides a description of VIC-Glacier (VIC-GL) model changes and upgrades.

  • Authors: Markus Schnorbus Publication Date: Jul 2022

    This report, the second volume in the VIC Generation 2 deployment reports, provides a description of modelling glacier dynamics with the HydroConductor Model.

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