Forest fires, climate change, and grizzlies
In North America, we’re feeling the heat. Quite literally. 2018 will be the 4th hottest year on world record, the top five having all occurred in the last six years (1). On the west coast, we have yet again been faced with tinder-dry conditions that have led to yet another summer of exhausted firefighters, overloaded emergency operations centres, displaced communities, and stressed wildlife. And, all this on top of 2017’s record-breaking 1.2 million hectares of burned land (2).
Fires change our landscapes, not only by consuming dead and dying plant life, but by changing the molecular state of our forests, soils, and even waters. We are reassured that this is a natural process - and that, once the smoke has settled, life rapidly returns, the now exposed minerals in the soil bringing forth new plants, fungi, and organisms that may not have had a chance to previously flourish. Plant species such as birch, aspen, or willow prefer open ground to shady canopies and are happy to pioneer new forests when landscapes are bare.
However, the cycle of fires is changing. The past four decades have shown that we are experiencing large fires more frequently (3). These frequent megafires may result in a loss of plant biodiversity - though seeds have a remarkable ability to remain productive after flames have passed, repeated scorching may diminish their ability to sprout (4). Should this frequency continue, our forests will be decimated just as they begin to recover, limiting plant life to the small and new, and resulting in landscapes that can foster only specific grasses and shrubs rather than a diverse range of tall trees (5). With no reprieve, there is no time for our natural world to bounce back, leaving wildlife homeless and hungry.
This stress is felt especially so by the ecologically sensitive grizzly. Climate change is altering food availability, and wildfires ravage the vegetation that grizzly bears depend on (6) (berries, grasses, sedges, etc.) as well as negatively impact fish runs (7) (8). When fires pass, temperatures rise in our lakes and slow-running streams, and particulate matter and loosened ash sweeps into the water, resulting in high levels of carbon which are bad for migrating fish (9). When salmon patterns change, grizzlies may not get enough of this critical food source - and having enough fat by the time they enter hibernation directly impacts whether they are able to reproduce over the winter.
Climate change has also contributed to the outbreak of mountain pine beetle which has led to the decline of whitebark pine in recent years, limiting yet another food source for grizzlies. Cold winters of past helped to kill the beetle, and summers of drought are leaving the trees susceptible to infestation (9). With yet another food source impacted by a changing climate, it is clear that grizzlies are facing an uphill battle.
Taking care of grizzlies requires people to consider numerous impacts. Urbanization, habitat fragmentation, road development, hunting in some areas, and human-bear conflict all relate to a grizzlies’ wellbeing. The impacts of climate change are limiting food sources and changing useful habitat for grizzlies, leaving them even more vulnerable. And we haven’t even touched upon the obvious - that fleeing fires takes a physical and mental toll on animals, and can be devastating to populations. Research indicates that up 10-28% of local vertebrate species will be lost due to climate change by 2070 (10).
Our choice is clear: take serious action now to address climate change, or accept recurring devastation from mega-wildfires that will overwhelm our health, our economy, and our wildlife.
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