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  • Authors: The Pacific Climate Impacts Consortium Publication Date: Feb 2018

    Three recent journal articles examine the rate of sea level rise and the ability of models to accurately simulate sea level rise at a global and regional scale.

    Publishing in Geophysical Research Letters, Yi et al. (2017) examine the rate at which sea level rise is accelerating and find that the rate of acceleration over the 2005-2015 period is three times faster than it was over the 1993-2014 period and an order of magnitude larger than the acceleration over the 1920-2011 period. They also identify three primary contributors to this acceleration: the thermal expansion of sea water, reduced storage of water on land and the melting of ice on land.

    In a pair of articles published in the Journal of Climate, Slangen et al. (2017) and Meyssignac et al. (2017) analyze the of climate models to simulate both global and regional sea level rise. They find that simulations can only explain about half (50% ± 30%) of the observed sea level rise. After bias corrections are included for the Greenland ice sheet and the possibility that ice sheets and the deep ocean were not in equilibrium with the 20th Century climate, the models explain about three-quarters (75% ± 38%) of the observed 20th Century sea level rise and all (105% ± 35%) of the observed sea level rise over the period from 1993-1997 to 2011-2015 period. Regionally, climate models underestimate the amount of sea level rise that occured, but do show reasonable agreement for interannual and multidecadal variability. When the same bias corrections are applied, the models come into closer agreement with observations. In addition, they find that the spatial variability in regional sea level rise is largely due to the thermal expansion of sea water and ongoing isostatic adjustment resulting from the end of the last glacial period.

  • Authors: Seiler, C. Publication Date: Jan 2018

    Extratropical cyclones (ETCs) intensify due to three vertically interacting positive potential vorticity anomalies that are associated with warm temperature anomalies at the surface, condensational heating in the lower-level atmosphere, and stratospheric intrusion in the upper-level atmosphere. It remains unclear how much each mechanism contributes to ETC intensification, as results from case studies are conflicting and a climatological assessment has not yet been done. Such a climatology would be useful for identifying sources of ETC biases and uncertainties in global climate models (GCMs). To fill this gap, this study presents the first climatology of mechanisms that generate intense ETCs in the Northern Hemisphere for the period 1980 to 2016 (3273 ETCs). Using piecewise potential vorticity inversion, I show that the lower level contributes most to maximum ETC intensification (52%), followed by the upper level (26%), and the surface (22%). These values vary during the last 36 hours prior to maximum ETC intensity, with decreasing surface contributions (from 35% to 22%) and increasing upper-level contributions (from 13% to 26%). The dominance of the lower level applies to 74% of ETCs, followed by the upper level (18% of ETCs) and the surface (8% of ETCs). Upper-level contributions are stronger in eastern than in western ocean basins, while the opposite applies to surface and lower-level contributions. This is consistent with regional patterns of potential vorticity anomalies, which, as discussed, may be associated with Rossby wave breaking and western boundary currents. The ability of GCMs to reproduce the mechanisms quantified in this study remains to be assessed.

  • Authors: The Pacific Climate Impacts Consortium Publication Date: Dec 2017
  • Authors: The Pacific Climate Impacts Consortium Publication Date: Dec 2017

    This newsletter discusses the publishing of rivers climate change indicators for the British Columbia (BC) Ministry of Environment and Climate Change Strategy, engineering design values for Island Health, progress on the development of the Climate Tool for Engineers, new partnerships with the Blueberry Council of BC and the Comox Valley Regional District, a paper on projected changes to summer mean wet bulb globe temperatures led by Chao Li, a Canadian Meteorological and Oceanographic Society article on extreme wildfire risk in the Fort McMurray area by Megan Kirchmeier-Young, a staff profile on Dr. Gildas Dayon, the PCIC Climate Seminar Series, a welcome to doctoral student Yaheng Tan, the release of PCIC's 2016-2017 Corporate Report, the release of a Science Brief on snowmelt and drought, the publishing of Climate Change Projections for the Cowichan Valley Regional District and State of the Physical, Biological and Selected Fishery Resources of Pacific Canadian Marine Ecosystems in 2016, as well as peer-reviewed publications since the last newsletter.

  • Authors: The Pacific Climate Impacts Consortium Publication Date: Oct 2017

    Two articles recently published in the peer reviewed literature examine how the rate of snowmelt may change as the Earth's climate changes, and how droughts can evolve and move over time.

    Publishing in Nature Climate Change, Musselman et al. (2017) examine the effect that global warming may have on snowmelt. They find that the portion of snow melt occurring at moderate and high melt rates in Western North America is projected to decrease, while the portion occurring at low melt rates is projected to increase. Total meltwater volume is projected to decrease.

    In recent research published in Geophysical Research Letters, Herrera-Estrada et al. (2017) explore how droughts evolve in space and time across six continents. They find that clusters of droughts can travel hundreds to thousands of kilometers across each continent. In addition, the authors find that longer-lasting droughts tend to travel farther, as well as be more severe.

  • Source Publication: Earth's Future, accepted, doi:10.1002/2017EF000639. Authors: Li, C., X. Zhang, F. Zwiers, Y. Fang and A. Micha Publication Date: Oct 2017

    Wet bulb Globe Temperature (WBGT) accounts for the effect of environmental temperature and humidity on thermal comfort, and can be directly related to the ability of the human body to dissipate excess metabolic heat and thus avoid heat stress. Using WBGT as a measure of environmental conditions conducive to heat stress, we show that anthropogenic influence has very substantially increased the likelihood of extreme high summer mean WBGT in northern hemispheric land areas relative to the climate that would have prevailed in the absence of anthropogenic forcing. We estimate that the likelihood of summer mean WGBT exceeding the observed historical record value has increased by a factor of at least 70 at regional scales due to anthropogenic influence on the climate. We further estimate that, in most northern hemispheric regions, these changes in the likelihood of extreme summer mean WBGT are roughly an order of magnitude larger than the corresponding changes in the likelihood of extreme hot summers as simply measured by surface air temperature. Projections of future summer mean WBGT under the RCP8.5 emissions scenario that are constrained by observations indicate that by 2030s at least 50% of the summers will have mean WBGT higher than the observed historical record value in all the analyzed regions, and that this frequency of occurrence will increase to 95% by mid-century.

  • Authors: Ouali, D. Publication Date: Oct 2017

    Talk delivered by Dr. Dhouha Ouali, PCIC Research Associate with the Marine Environmental Observation Prediction and Response Network on October 25th, 2017.

    Regional frequency analysis (RFA) of hydro-meteorological variables is a commonly used tool to provide quantile estimates of extreme events at ungauged sites. Given the high complexity of hydro-meteorological processes, it is worthwhile to account for the possible nonlinear connections between hydro-meteorological variables and catchments characteristics in all RFA steps. Moreover, to provide relatively reliable quantiles estimates, it is often recommended to only consider sites with sufficiently long data series which lead to ignoring a considerable part of the available information. A number of regression-based RFA methods are proposed to remedy the limitations of the classical approaches, mainly dealing with the non-linear aspect and the exploitation of the hydro-meteorological data. Comprehensive comparisons are carried out between the classical and the proposed methodologies using 151 hydrometric stations from the province of Quebec. The performances of the proposed methods are assessed using new and classical evaluation criteria in a cross-validation procedure.

  • Authors: The Cowichan Valley Regional District and the Pacific Climate Impacts Consortium Publication Date: Sep 2017

    Temperatures in the Cowichan Valley are warming. Global climate models project an increase in annual average temperature of almost 3°C in our region by the 2050s. While that may seem like a small change, it is comparable to the difference between the warmest and coldest years of the past. The purpose of this report is to quantify, with the most robust projections possible, the related climate impacts (including changes to climate extremes) associated with warming. This climate information will then inform regional risk assessment, decision making, and planning in the Cowichan Valley region, with a goal of improving resilience to
    climate change. For this reason, this report focusses on the business-as-usual emissions scenario and the 2050s timeframe. By the end of the 21st century, projected warming and associated impacts are even larger. In addition, the amount of warming by that time depends more highly on the quantity of greenhouse gases emitted in the meantime.

  • Authors: Megan C. Kirchmeier-Young, Francis W. Zwiers, Nathan P. Gillett and Alex J. Cannon Publication Date: Jul 2017

    Canada is expected to see an increase in fire risk under future climate projections. Large fires, such as that near Fort McMurray, Alberta in 2016, can be devastating to the communities affected. Understanding the role of human emissions in the occurrence of such extreme fire events can lend insight into how these events might change in the future. An event attribution framework is used to quantify the influence of anthropogenic forcings on extreme fire risk in the current climate of a western Canada region. Fourteen metrics from the Canadian Forest Fire Danger Rating System are used to define the extreme fire seasons. For the majority of these metrics and during the current decade, the combined effect of anthropogenic and natural forcing is estimated to have made extreme fire risk events in the region 1.5 to 6 times as likely compared to a climate that would have been with natural forcings alone.

  • Authors: The Pacific Climate Impacts Consortium Publication Date: Jul 2017

    To plan for and adapt to the potential impacts of climate change, there is a need among communities in British Columbia for projections of future climate and climate extremes at a suitable, locally-relevant scale. This report summarizes work completed in 2012 by the Pacific Climate Impacts Consortium (PCIC) to this end. Commissioned by a group of municipalities and regional districts in the Georgia Basin (Figure 1), PCIC developed and analyzed a set of projections of future climate and climate extremes for the area. The full report, Georgia Basin, Projected Climate Change, Extremes and Historical Analysis, is available from PCIC’s online publications library.

  • Authors: Zwiers, F. Publication Date: Jun 2017

    Public talk delivered by Francis Zwiers at the 51st Annual CMOS Congress, June 6th, 2017

  • Authors: The Capital Regional District, the Pacific Climate Impacts Consortium, Pinna Sustainability Publication Date: Jun 2017

    Temperatures in the Capital Regional District (CRD) are warming. Global climate models project an average annual warming of about 3°C in our region by the 2050s. While that may seem like a small change, it is comparable to the difference between the warmest and coldest years of the past. The purpose of this report is to quantify, with the most robust projections possible, the related climate impacts (including changes to climate extremes) associated with warming. This climate information will then inform regional vulnerability and risk assessments, decision-making, and planning in the capital region, with a goal of improving resilience to climate change.

  • Source Publication: 56, 6, 1625–1641, doi:10.1175/JAMC-D-16-0287.1 Authors: Sobie, S.R. and T.Q. Murdock Publication Date: Jun 2017

    Knowledge from high-resolution daily climatological parameters is frequently sought after for increasingly local climate change assessments. This research investigates whether applying a simple postprocessing methodology to existing statistically downscaled temperature and precipitation fields can result in improved downscaled simulations useful at the local scale. Initial downscaled daily simulations of temperature and precipitation at 10-km resolution are produced using bias correction constructed analogs with quantile mapping (BCCAQ). Higher-resolution (800 m) values are then generated using the simpler climate imprint technique in conjunction with temperature and precipitation climatologies from the Parameter-Elevation Regression on Independent Slopes Model (PRISM). The potential benefit of additional downscaling to 800 m is evaluated using the “Climdex” set of 27 indices of extremes established by the Expert Team on Climate Change Detection and Indices (ETCCDI). These indices are also calculated from weather station observations recorded at 22 locations within southwestern British Columbia, Canada, to evaluate the performance of both the 10-km and 800-m datasets in replicating the observed quantities. In a 30-yr historical evaluation period, Climdex indices computed from 800-m simulated values display reduced error relative to local station observations than those from the 10-km dataset, with the greatest reduction in error occurring at high-elevation sites for precipitation-based indices.

  • Authors: The Pacific Climate Impacts Consortium Publication Date: Jun 2017

    The June 2017 PCIC Update covers the following stories: The VIC-GL Model Now Operational, Climate Variability: the Hot Cold Winter of '16-'17, Nature Geoscience Paper on Short-Duration Extreme Rainfall Events, Staff Profile: Mohamed Ali Ben Alaya, as well as PCIC in the news, an invited lecture by Francis Zwiers on Extreme Weather at CMOS, recent talks, a new Science Brief, staff changes and recent papers authored by PCIC Staff.

  • Authors: Katherine A. Pingree-Shippee, Francis W. Zwiers and David E. Atkinson Publication Date: Jun 2017

    Talk delivered by Katherine Pingree-Shippee at the 51st Annual Congress of the Canadian Meteorological and Oceanographic Society, in June of 2017.

  • Authors: Bechtet, N. and T. Murdock Publication Date: Jun 2017

    Presentation by PCIC Intern Noémie Bechtet on an analysis of a survey done on the users of PCIC's online tools.

  • Source Publication: Journal of Climate, 30, 4113-4130, doi:10.1175/JCLI-D-16-0189.1 Authors: Naja , M.R., F.W. Zwiers and N.P. Gillett Publication Date: May 2017

    A detection and attribution analysis on the multidecadal trend in snow water equivalent (SWE) has been conducted in four river basins located in British Columbia (BC). Monthly output from a suite of 10 general circulation models (GCMs) that participated in phase 5 of the Coupled Model Intercomparison Project (CMIP5) is used, including 40 climate simulations with anthropogenic and natural forcing combined (ALL), 40 simulations with natural forcing alone (NAT), and approximately 4200 yr of preindustrial control simulations (CTL). This output was downscaled to 1/16° spatial resolution and daily temporal resolution to drive the Variable Infiltration Capacity hydrologic model (VIC). Observed (manual snow survey) and VIC-reconstructed SWE, which exhibit declines across BC, are projected onto the multimodel ensemble means of the VIC-simulated SWE based on the responses to different forcings using an optimal fingerprinting approach. Results of the detection and attribution analysis shows that these declines are attributable to the anthropogenic forcing, which is dominated by the effect of increases in greenhouse gas concentration, and that they are not caused by natural forcing due to volcanic activity and solar variability combined. Anthropogenic influence is detected in three of the four basins (Fraser, Columbia, and Campbell Rivers) based on the VIC-reconstructed SWE, and in all basins based on the manual snow survey records. The simulations underestimate the observed snowpack trends in the Columbia River basin, which has the highest mean elevation. Attribution is supported by the detection of human influence on the cold-season temperatures that drive the snowpack reductions. These results are robust to the use of different observed datasets and to the treatment of low-frequency variability effects.

  • Authors: Markus Schnorbus, Brian Menounos, Arelia Schoeneberg, Faron Anslow, Georg Jost and Dan Moore Publication Date: May 2017

    Presentation delivered by Markus Schnorbus at the Canadian Geophysical Annual meeting in May of 2017.

  • Authors: The Pacific Climate Impacts Consortium Publication Date: May 2017

    Two recently published articles explore how projected changes to climate and carbon dioxide in the atmosphere may affect grasslands in temperate regions and three crops in the United States. Addressing the first question in Nature Climate Change, Obermeier et al. (2017) find that the carbon dioxide fertilization effect in C3 grasslands is reduced when conditions are wetter, dryer or hotter than the conditions to which the grasses are adapted.

    Publishing in Nature Communications, Schauberger et al. (2017) examine the second question. They find that yields for wheat, soy and corn decline at projected temperatures greater than 30°C, with reductions in yield of 22% for wheat, 40% for soy and 49% for corn. While carbon fertilization does reduce the loss in yields, the effect is much smaller than that of irrigation, suggesting that water stress at higher temperatures may be largely responsible for losses.

  • Source Publication: Nature Geoscience 10, 255–259, doi:10.1038/ngeo2911. Authors: Zhang, X., F.W. Zwiers, G.L. Hui Wan and A.J. Cannon Publication Date: Mar 2017

    Warming of the climate is now unequivocal. The water holding capacity of the atmosphere increases by about 7% per °C of warming, which in turn raises the expectation of more intense extreme rainfall events. Meeting the demand for robust projections for extreme short-duration rainfall is challenging, however, because of our poor understanding of its past and future behaviour. The characterization of past changes is severely limited by the availability of observational data. Climate models, including typical regional climate models, do not directly simulate all extreme rainfall producing processes, such as convection. Recently developed convection-permitting models better simulate extreme precipitation, but simulations are not yet widely available due to their computational cost, and they have their own uncertainties. Attention has thus been focused on precipitation–temperature relationships in the hope of obtaining more robust extreme precipitation projections that exploit higher confidence temperature projections. However, the observed precipitation–temperature scaling relationships have been established almost exclusively by linking precipitation extremes with day-to-day temperature variations. These scaling relationships do not appear to provide a reliable basis for projecting future precipitation extremes. Until better methods are available, the relationship of the atmosphere's water holding capacity with temperature provides better guidance for planners in the mid-latitudes, albeit with large uncertainties.

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