Publications Library

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.

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.

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.

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

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

This, the fifth volume in the VIC Generation 2 deployment reports, provides a description of model calibration.

A strong atmospheric river made landfall in southwestern British Columbia, Canada on November 14th, 2021, bringing two days of intense precipitation to the region. The resulting floods and landslides led to the loss of at least five lives, cut Vancouver off entirely from the rest of Canada by road and rail, and made this the costliest natural disaster in the province's history. Here we show that when characterised in terms of storm-averaged water vapour transport, the variable typically used to characterise the intensity of atmospheric rivers, westerly atmospheric river events of this magnitude are approximately one in ten year events in the current climate of this region, and that such events have been made at least 60% more likely by the effects of human-induced climate change. Characterised in terms of the associated two-day precipitation, the event is substantially more extreme, approximately a one in fifty to one in a hundred year event, and the probability of events at least this large has been increased by a best estimate of 45% by human-induced climate change. The effects of this precipitation on streamflow were exacerbated by already wet conditions preceding the event, and by rising temperatures during the event that led to significant snowmelt, which led to streamflow maxima exceeding estimated one in a hundred year events in several basins in the region. Based on a large ensemble of simulations with a hydrological model which integrates the effects of multiple climatic drivers, we find that the probability of such extreme streamflow events in October to December has been increased by human-induced climate change by a best estimate of 120–330%. Together these results demonstrate the substantial human influence on this compound extreme event, and help motivate efforts to increase resiliency in the face of more frequent events of this kind in the future.

This issue of the PCIC Update covers the following stories: Downscaled CMIP6 Data Now Available; Release of the Design Value Explorer; IPCC Reports on Impacts, Adaptation, Vulnerability and Mitigation; and New Section and Sector Modules on ClimateData.ca. The Science Brief mentioned in this issue is on changes to Western Canadian glaciers. The talks discussed in this issue were delivered by Professor Ted Shepherd, Dr. Mohamed Ali Ben Alaya, Dr. Nathan Gillett and Markus Schnorbus, Dr. John Fyfe, Dr. Paul Kushner and Dr. Hans von Storch. The staff profile in this issue is on Stacey O'Sullivan.

On 6–8 January 2021, a cold air outbreak swept across eastern China, peaking over the North China Plain the night of 6 January, when 219 weather stations recorded the lowest nighttime temperature since 1961. In total, 498 stations recorded the lowest daytime or nighttime temperature since 1961 during the 3-day event. This event, together with two other cold outbreaks that affected the region on 13–15 December 2020 and 29 December 2020–1 January 2021, led to historic peak electricity demand and resumption of the operation of the only remaining coalfired generating plant in Beijing. This analysis puts the cold outbreak into historical perspective by considering changes in the likelihood of such events over 1961–2020 in the context of a climate that is being warmed by anthropogenic forcing.