Trees, and the climate forecast for Victoria

Expect hotter summers and winter deluges. Retaining trees could reduce the worst impacts, including the cost of mitigation.

AS SUMMER FADES, along with memories of warm, sunny days, three recent reports help us turn a thought to the future and what Greater Victoria’s weather will look like three decades from now: Start stocking up on triple-strength sunscreen and waterproof storm gear.

By the 2050s, with an average annual warming of about 3°C in the Capital Region, the number of scorching hot days will triple; fall and winter will see more extreme weather events, with deluges replacing Greater Victoria’s trademark showers, says a report prepared for the Capital Regional District.

Climate Projections for the Capital Region, written by Trevor Murdock and Stephen Sobie from Pacific Climate Impacts Consortium and Gillian Aubie Vines from Pinna Sustainability, looks at how climate change will unfold over the coming decades—and the future is hot. “Monthly high and low temperatures show that the new normal for the region may be very unlike the past,” says the report, which is based on the assumption that global greenhouse gas emissions will continue at their current rate. “Rising temperatures will lead to hotter summer days and nights, milder winters with the near loss of frost days and snowpack in all but the highest elevation locations.” Overall, it predicts a 69 percent decrease in the number of frost days and a 90 percent decrease in snowpack depth in the mountains by the 2080s.

That translates into the number of summer days with a temperature above 25 degrees Celsius rising to 36 days a year, from an average of 12 days a year from 1971 to 2000. The temperature for the 1-in-20-year hottest day will soar to a scorching 36 degrees from the current 32 degrees, with an increase to 38 degrees by the 2080s. By that time, Greater Victoria will also be experiencing an average of four “tropical nights,” meaning the overnight low temperature is higher than 20 degrees. “This measure is important as a series of hot nights can cause heat stress in vulnerable populations (e.g. those with compromised immune systems) and will have an impact on energy used for cooling buildings during warm spells,” says the report.

There will be less rain in summer, with a 20 percent reduction in precipitation, but fall and winter will have more extreme wet weather events and could see 68 percent more rain falling during very wet days. Overall, there is likely to be a five percent increase in precipitation by the 2050s and 12 percent by the 2080s.

The changes will affect all aspects of life in the Capital Region, from health to food supplies. A longer summer tourism season could be a bonus, but might be offset by a decline in winter tourism, and long periods of hot, dry weather could put pressure on lakes, beaches and coastal waters used for recreation, according to the report. “With the potential of increased nutrients deposited in freshwater lakes, we can expect to see more algal blooms become a challenge for ecosystems and recreational water users,” it says. “When hot, dry summers are combined with extreme storms in the wet season, we can expect shoreline access, water quality, wildlife habitat and recreational infrastructure to require ongoing maintenance.”

Although there will be a longer season for growing food, migrating pests and water availability are likely to become problems for farmers and “in some cases, land including agricultural areas, could suffer from saltwater intrusion from rising sea levels, or need to be restored as wetlands to manage storm water across the region.”

The aim of the report is to allow local politicians, organizations and the public to plan and adapt to the coming changes, said the authors. Lead author Gillian Aubie Vines tells Focus, “I think it’s really time for greater awareness of what we are projecting. It’s a great opportunity for public policy-makers, scientists and engineers.”

The report will help map out changes in engineering designs and urban planning, says Aubie Vines, who has helped prepare similar reports for the Cowichan Valley and Metro Vancouver. “It gets our minds around what we can do—like cooling stations and insulating buildings so they are efficient.”

The wider implications include agricultural plans that can deal with heat, pests and flash floods, and the possibility of an increasing number of people moving to Vancouver Island because of its comparatively mild climate. “As California becomes hotter, Vancouver Island is going to look nicer and nicer,” predicts Aubie Vines, and she believes both mitigation and adaptation are required. “We need to stop emitting and we need to adapt to what is happening.”

Many political leaders at the CRD understand the urgency, but surprisingly, climate change deniers—or those who believe it is a problem best ignored—still have a voice, and that is why the report, setting out scenarios in plain language, is so important, according to Aubie Vines. “After a process like this, after people are forced to think about it more deeply, it’s impossible to deny,” she said.

AS BC’s CLIMATE HEATS UP and becomes more unpredictable, the province’s forests can help mitigate problems. Climate researchers with the Forest Carbon Management Project have concluded that relatively minor changes to forest management could meet more than one-third of the province’s 2050 carbon-emissions reduction target.

Better forest management, removing slash from the forest and using it for bioenergy—rather than burning it on site—is one measure that will assist in carbon dioxide management. The research also shows that promoting the use of wood products, instead of concrete and steel, and converting a small percentage of fibre destined for pulp and paper into longer-lasting wood panels are other measures needed to increase the role of forests in carbon dioxide management. The multi-year project, led by the Pacific Institute for Climate Solutions and based at the University of Victoria, includes scientists from Natural Resources Canada and UBC.

Small changes to forest management, including reducing the harvest by two percent between now and 2050, could have a major impact, delivering 18.2 megatonnes of carbon dioxide equivalent, project leader Werner Kurz explained at a recent public presentation in Vancouver. “By 2050, 35 percent of BC’s emission reduction target can be contributed by the forest sector at less than $100 a tonne of carbon dioxide equivalent.”

Although $100 a tonne may sound expensive, other methods, such as carbon capture and storage, come in at between $200 and $300 a tonne, explains Kurz, a senior research scientist with Natural Resources Canada. The measures, he says, would also provide socio-economic benefits by creating 2000 new full-time jobs, as more intensive forest management would be required. He points out that the changes would also mean healthier forests, and emphasizes that the project needs investment now so that the science can inform policy decisions.

BC has a legislated greenhouse gas emission reduction target of 80 percent below 2007 levels by 2050. To meet those targets, Kurz says, it is necessary to not only reduce the burning of fossil fuels, but to find ways to remove more carbon dioxide from the atmosphere.

While 44 percent of greenhouse gas emissions remain in the atmosphere, the remainder is taken up by forests and oceans, Kurz told his audience in Vancouver. “That leads to ocean acidification, so it is not desirable, and there is also a question of how long forests will continue to be carbon sinks,” he said.

The province’s 55 million hectares of forest lands are already being affected by climate change, according to UBC researchers working on the project. Wetter areas are benefitting from warmer conditions and increased carbon dioxide levels, while drier areas are struggling with slower growth and increased tree mortality.

The provincial government (under the Liberals) announced in February that it would spend $150 million to rehabilitate forests damaged by fire and disease and to increase BC’s carbon sink. The new NDP provincial government has pledged to renew BC’s forests by (among other things) expanding investments in reforestation. It has also created a ministry of the environment and climate change strategy with George Heyman as minister.

A THIRD STUDY, also involving trees and the weather, provides evidence that streets without trees are uncomfortably windy, and that buildings around which trees have been removed use more energy. The paper from UBC scholars was published in July in Advances in Water Resources. It found that losing even one tree increases wind pressure and drives up heating costs in nearby buildings.

Lead author Marco Giometto, a postdoctoral fellow in civil engineering, says that a single tree can help keep pedestrians comfortable. “We found that removing all trees can increase wind speed by a factor of two, which would make a noticeable difference to someone walking down the street,” he said in a news release. “For example, a 15-km-per-hour wind speed is pleasant, whereas walking in 30-km-per-hour wind is more challenging.”

Researchers, who used laser technology to create a model of a typical Vancouver neighbourhood, found that removing all trees around buildings drove up energy consumption by 10 percent in winter and 15 percent in summer. Even winter trees, with bare branches, can moderate airflow and wind pressure, which makes for a more comfortable environment, the study found.

The information could be used to improve weather forecasts and predict the effect of storms on buildings, or on pedestrians walking along certain sidewalks, says co-author and UBC geography professor Andreas Christen. “It could also help city planners in designing buildings, streets and city blocks to maximize people’s comfort and limit wind speed to reduce energy loss.”

Judith Lavoie is an award-winning journalist specializing in the environment, First Nations, and social issues. Twitter @LavoieJudith.