Smokanagan: New normal?

Given the smoky summers we’ve had for the past few years, it is reasonable to wonder whether we can expect more of the same every summer from now on:

• evacuations
• poor air quality
• cancelled sporting events
• and so on.

Last August, if you flew from Vancouver to Calgary, the only thing you would see sticking out of a sea of smoke was the tips of the Rockies and Columbia mountains.

So what does the latest science tell us about what to expect in the future?

Predicting forest fire behaviour is a complex science that accounts for:

• forest fuel load,
• weather,
• atmospheric stability,
• topography
• air and vegetation moisture
• forest management practices
• previous fires
• ignition sources.

But in terms of the colossal fires that burn the overwhelming majority of forest and cause most of the lingering smoke, these are mainly the result of a few critical days with three combined factors: hot, dry, windy weather.

A simple rule of thumb used by wildfire fighters is the 30-30-30 crossover: when temperatures exceed 30°C, humidity is below 30%, and winds are above 30 km/h, fire hazard is extreme.

One careless toss of a cigarette butt or a spark from heavy equipment in these conditions is a recipe for disaster.

Predicting future forest fires is especially tricky, because although temperatures are expected to increase globally, some factors like rainfall frequency will also increase in some areas.

While most regions can expect more forest fires as a result of global warming, some regions will experience reduced forest fire activity because of localized increases in rainfall frequency.

Scientists at the University of Alberta, B.C. Ministry of Forests, and Natural Resources Canada have modelled future burn probabilities in the Thompson-Okanagan.

They anticipated more ignitions due to lightning and higher temperatures, both of which factors lead to increased forest fires. But these effects may be offset by lower wind speeds, higher relative humidity and a shift to less flammable forest cover over the next six decades.

The net result is an overall decrease in forest fire activity in the region. This may be counterintuitive, but a major factor is a shift from the lodgepole pine trees that are prone to crowning fires to the less flammable red cedar, hemlock and mixed conifer forests.

But because this decline entails a major shift in forest type, it would take several decades to offset the concurrent warming. And because our forests are so heavily managed, the time to realize these reductions will depend on the extent to which forest planners include climate change analysis and fire resiliency in their re-planting strategies.

Dr. Mike Flannigan of the University of Alberta has studied wildfire dynamics for over 30 years. He says wildfire behaviour is all about the extremes, with most large fires attributable to a few days of extremely hot and dry conditions (like the 30-30-30 rule).

As the climate warms, we can expect a longer fire season, more lightning strikes, and more efficient drying of fuels. This year we could encounter such conditions, since the warming effects of El Niño have persisted longer than usual into the summer.

On top of those factors, the warmer climate has allowed mountain pine beetle to decimate much of our forests, resulting in dead, dry lodgepole pine across much of Interior BC – though most of the dead stands are northwest of the Okanagan.

Dr. Daniel Perrakis researches mountain pine beetles and wildfires for Natural Resources Canada. In his opinion, the main thing we can expect from future forest fires is greater variability – a sentiment shared by Dr. Flannigan.

Data from the past few years demonstrate this variability. 2017 and 2018 were extreme years in terms of numbers of fires, area burned, numbers of evacuations, and total cost or suppression.

2016 was typical overall, but unusual in terms of having wildfires early in the season. 2014 and 2015 were unusually high in terms of fire activity. 2011, in contrast, was one of the lowest wildfire years on record, due to cool and wet conditions.

And of course, one only needs to glance at Okanagan Mountain Park to remember the disaster that was 2003 – BC’s worst year in terms of wildfire damage to communities.

The Thompson-Okanagan is one of the most highly affected regions in Canada with regards to Wildland-Urban-Interface fires. Most communities in this region are built right up to and even into the forest.

This is both a feature and bug; the ability to live in the forest draws people to this beautiful region, but it has resulted in over 350,000 people being directly affected by forest fires in the last decade and a half.

With the recent announcement by the regional district that fire hazard is now high and moving toward extreme, all we can do as individuals is to be prepared.

We should have an evacuation plan and maintain a fire break between trees and your house if you live anywhere near the forest interface;.

Do our best to prevent fires and respect the fire bans that are likely to be the norm each summer.

And, for the love of God, don’t toss butts out the car window.

This article is written by or on behalf of an outsourced columnist and does not necessarily reflect the views of Castanet.