The climes they are a’changing

Columbia Basin Trust releases new climate change report

Climate in the Columbia Basin — in Kimberley — is changing. In fact a new report from the Columbia Basin Trust, ‘From Dialogue to Action: Climate Change, Impacts and Adaptation in the Canadian Columbia Basin, recently released as part of its Communities Adapting to Climate Change Initiative, says by the 2050s average annual temperatures could rise 1.6 to 3.2 degrees Celsius.

The new report and an executive summary are a continuation of work begun in 2007 with a CBT report entitled ‘Starting the Dialogue’.

“The climate in our Basin has changed over the last 50 years and is projected to continue changing over the coming decades, so providing communities and residents with current information about climate impacts and adaptation can help them plan to be more resilient to these changes,” said Kindy Gosal, CBT Director, Special Initiatives.

Why should anyone worry about  a warming climate?

As the report outlines, a change of two degrees or even less may seem small, but it can actually have profound effects on ecosystems and human health. It can effect the tourist economy in both positive and negative ways. A longer summer would be a positive for golf and camping, but warmer winters may mean more rain than snow which would have a negative effect on the ski industry.

More precipitation in the winter can also mean unstable hillsides, more landslides. Extra precipitation was certainly in evidence this past winter runoff season with landslide events in many parts of the province.

Here are some of what the report says will occur as temperatures rise in the Columbia Basin:

Glacier Runoff: Between 1986 and 2000, there was a 16 per cent loss of total glacial area in the Basin. Most of BC’s glaciers are continuing to lose mass and many may disappear within the next 100 years.

Glaciers are essential freshwater reservoirs that contribute significantly to stream flows in late summer and fall. Declines in summer flows from glaciers may occur in the future as the volume of ice declines.

Water Temperatures: Rising summer air temperatures and diminishing cold water inputs from glaciers may increase water temperatures in Basin streams and lakes. This could affect temperature-sensitive aquatic species like bull trout, disrupt the development of fry in some species and impact water quality if different bacteria and algae start to flourish.

Stream Flows: Changes in stream flows may occur as some Basin rivers and streams shift from being snow-dominated to hybrid or rain-dominated.

Stream flows will also be impacted by an earlier spring melt, earlier peak flows, lower late-summer flows and higher winter flows. A study of south-central BC found that the spring peak flow occurred an average of 20 days earlier between 1984 and 1995 than between 1970 and 1983.

Freeze/Thaw Changes in the frequency of freeze/thaw cycles may vary from location to location. At locations where temperatures currently fluctuate near zero during the spring, winter and fall seasons, increased temperatures may result in fewer freeze/thaw events. Where temperatures often hover just below zero, more frequent freeze/thaw cycling may occur. Sites that are consistently well below zero may have a similar frequency of freeze/thaw events as they have had historically, although they may occur later in fall and earlier in spring.

Rain-on-snow: The projected warming and increases in winter precipitation falling as rain could result in an increase of rain-on-snow and rain-on-frozen-ground events in the Basin. These events create more runoff than rain falling on soil because they cause a partial melt and may, in certain circumstances, trigger landslides, mass-wasting or flooding.

Flooding: There may be greater potential for flooding due to more frequent and intense rainstorms, increased glacier melt, more rain-onfrozen-ground and rain-on-snow events, and higher winter peak flows. Flooding may also occur more frequently in late winter or early spring than in the past.

Droughts: Summer soil moisture levels may decline due to smaller winter snowpacks at lower elevations, less summer rainfall and warmer summer temperatures with more hot days and longer warm spells. These conditions create the potential for more frequent and intense drought periods.

Diseases and Pathogens: Projected increases in temperature and precipitation in some seasons may contribute to an increase or prolonged transmission cycle of certain diseases and the ranges of disease-causing agents, such as mosquitoes, ticks, rodents and fungi.

Wildfires: The area burned in BC was declining since the early part of the 20th century, but started to rise again in the last two decades, as has the length of the wildfire season.

Projected increases in summer temperatures, very hot days, longer warm spells, reduced summer precipitation, fuel accumulation and pest outbreaks may contribute to increased wildfire frequency. By 2100, fire starts in BC have been projected to increase by 21 per cent to 190 per cent, with regional variation.

Landslides and Avalanches: Projected increases in winter precipitation, the frequency of extreme rainfall events and wildfire could all contribute to increased landslide frequency in the future.

Reduced snowpack could decrease avalanches in some locations, while increases in winter temperatures, rain-on-snow events and increases in freeze/thaw cycling could increase avalanche frequency in other locations.

Biodiversity: The species found in Basin ecosystems today are based largely on climate conditions of the past. As the climate changes, some species will tolerate the new conditions, some may migrate north or up-slope, and others may decline. New and unique combinations of species may occur. Conditions may increasingly favour invasive species, pests, deciduous trees and generalized grasslands.

Wetlands and alpine tundra ecosystems may decline, while forest ecosystems may migrate north and up-slope where conditions permit.

The upshot is any or all of the above changes could occur over the next decades and communities need to be aware and prepared to deal with them.

For instance, the report says, these potential changes should be considered in all long-term decision making by communities. Improving health planning and monitoring for heat waves or poor air quality, improving planning for emergencies and possible evacuations, fire smarting and water conservation are all part of actions communities can take.

The full report can be viewed at www.cbt.org/dialoguetoaction and the executive summary at www.cbt.org/dialoguetoactionsummary. There is also a video at www.cbt.org/dialoguetoactionvideo