Vancouver summers could get as warm as San Diego by 2050: Report

A September 2016 climate projections report by Metro Vancouver has made some eye-raising predictions.

The effects this vastly different climate could play on the region are outlined in the report, which forecasts how each season will change as our climate warms. In the next 30-plus years, the “new normal” could include dry and hot summers, heavy downpours throughout the winter, and virtually no frost or snow at lower elevations.

The report used current climate model outcomes to provide a “best guess” snapshot of how climate change will unfold in Metro Vancouver over the coming decades.

“People who plan in Metro Vancouver for things like dealing with heat waves and human health impacts of hot temperatures can look at current-day San Diego for an idea of what to plan for by the middle of the century,” said Trevor Murdock, a climate scientist who contributed to the study.

With climate modelling by Pacific Climate Impacts Consortium, the study used “business-as-usual” greenhouse gas (GHG) emissions scenario to make its projections. “Business-as-usual” is defined as the level of emissions that would result if future development follows past trends and no policy changes take place. Since there is the potential for confusion around projected GHG emissions levels, it’s important to know what lies beneath the projection, as stated by the Intergovernmental Panel on Climate Change (IPCC).

The report clearly outlines the information provided “is intended to describe a probable future and enable our region’s planners, engineers, and policy makers to make better-informed decisions on how to plan and adapt to changes ahead. This information could support development of design guidelines for future planning.”

“This kind of a study is important for Metro Vancouver because we build infrastructure that is very long-lived so when the climate is changing we need to prepare for that well in advance,” Metro Vancouver’s Jeff Carmichael said.

Shift in seasonal temperatures

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Most notable will be the shift in temperatures across all four seasons. Summers will be hot, with average daytime temperatures peaking at 24.7 C in 2050 and 27 C in 2080, compared to today’s average of 21 C.

Summers will stretch later into the fall with autumn highs hovering around the high teens, and in the winter, daytime highs in January will be closer to those of March today.

According to the study, the warmest day of the winter is typically about 12 C, but in 2050 it could get up to 15 C and by 2080, 18 C. Similarly, the study says winter’s coldest night will go from -13 C today to only -5 C in 2080. Metro Vancouver would experience wintertime lows of -13 C only once in every 20 years by 2080.

And on hot days, it will get much hotter.

The study’s data projections show so-called “tropical nights” – when nighttime lows are warmer than 20 C – will increase from an overage of zero days a year currently, to four in 2050 and 19 by 2080. And the hottest day of the year will grow from an average of 31 C today to 35 in 2050 and 37 in 2080. The number of days where temperatures exceed 30 C will spike from two presently to 29 by 2080.

Rain and snow

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Temperatures aren’t the only thing that are going to change, the study also indicates an impact on precipitation.

Fall, winter and spring will be much wetter while summers will be significantly drier. Rain is expected to fall in heavy downpours and, in “extreme events” more often, which could raise concerns for flooding, landslides and stream overflow, according to the report. Summer and early fall months will see variable precipitation, with droughts occurring some years and more rain falling during others.

Both the warmer temperatures and high precipitation, the study says, could impact Metro Vancouver’s snowpack. The report estimates there could be a 56 per cent decrease in winter snowpack by the 2050s and a 77 per cent decrease by the 2080s. Spring snowpack could be even harder hit, with a projected 84 per cent decrease by the 2080s.

Agriculture

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Climate changes could affect the region’s agriculture sector, with a projected increase in the growing season from 252 days a year today to 357 days on average by the 2080s. The report suggests this would cause both positive and negative impacts to the industry, giving farmers more variety in the crops they can grow and higher yields, but also causing heat stress on plants during hot summer months.

Ecosystems

Similar issues could be found in Metro Vancouver’s ecosystem. The report says an increased risk of wildfires could decimate forest population surrounding the region while a spike in tree mortality, decreased plant growth and scarcity of water will decrease the food supply for wild animals.

A light streamflow in summer months, coupled with warmer water temperatures, could also cause stress on fish and aquatic animals.

Comparatively, the Metro Vancouver report theorizes pests and invasive species, whose activities are currently mitigated by cold temperatures, could thrive under the “new normal.”

Shifting energy use

The study cautions urban planners, engineers and developers should note these projections because buildings will need to be built with new specifications. Warmer nighttime temperatures, for instance, will mean buildings won’t be able to cool themselves without air conditioning.

The study estimates that buildings at lower elevations will have more cooling demand than present-day Kamloops by 2050 and a higher cooling demand than present-day San Diego by the 2080s.

Scroll below for visualizations of the study’s data:

James Tansey, an associate professor with the Sauder School of Business, said that such climate models have value, but trying to predict long-term climate patterns can be incredibly difficult.

“The challenge for an area the size of Vancouver is you’re working with global circulation models that  each cell within the model might be 500 square kilometres and what you’re trying to do is look at global effects and then downscale them to 500 square kilometres and then work out what’s happening in a relatively small portion of that region,” he said.

“It’s just extremely difficult to do. We’re all used to how unreliable weather forecasts are … Climate models are dramatically more complicated than weather forecasts.”

Tansey said that when it comes to climate change, the best approach may be to expect the unexpected.

“It’s not guaranteed to go in one directions or the other, but it’s going to be highly variable,” he said.

– With files from Neetu Garcha and Jon Azpiri