In Western Canada, climate change takes the form of a hungry maw
In the April 2007 issue of The Walrus, Patrick White reported on an epidemic of mountain pine beetle wreaking havoc on the forests of British Columbia. The population of the pine-killing pest, a native resident of western North America’s forests, began to explode in 1993, and has laid waste to much of BC’s pine. The infestation is now receding there, moving on to Alberta and the US. Vigilance and luck appear to have kept it from traveling any further east across Canada, but the lesson learned is a hard one: even well-intentioned human interventions in the ecosystems we live in and use can have surprisingly devastating effects.
The size of the beetle epidemic is massive. Between mountain pine beetles and wildfires, BC’s half-million square kilometres of forest actually became a net emitter of carbon in 2002 (PDF download), and are expected to remain so until 2020. What should be a valuable carbon sink instead unleashed the equivalent of 40-60 million tonnes of CO2 in 2007 (although this figure includes the carbon contained in wood harvested during that year). Thankfully, Alberta has learned from BC’s example, mounting a swift response that seems to be holding back the outbreak. The sharp winter drops in temperature that would normally have helped to control the beetles also finally showed themselves over the last few years — although too late to save over 600 million cubic metres of British Columbian trees.
The main reasons for this outbreak’s severity are generally put down to two innocuous-sounding factors: slowly rising average temperatures brought on by global warming, and decades of fire prevention by forest management authorities. The warming has made it ever less likely that winter temperatures will dip low enough to kill the beetles; fire suppression has created forests unnaturally dense with old trees — ripe ground for both severe fires and hungry beetles. It is thanks to the complexity of ecosystems that a few degrees of warmth and an effectively carried out fire-fighting policy could have these counter-intuitively disastrous results.
Of course, the complexity of the British Columbian forests pales in comparison to that of the entire global climate. So it is a shame that the label ‘global warming’ has given a lot of people such a terrifically oversimplified view of the phenomenon (one brave soul has been dutifully cataloguing the streams of moronic editorial cartoons on the subject at “If Global Warming Is Real Then Why Is It Cold”). It’s an understandable simplification; our everyday experience of “temperature” is of a number on the thermometer that tells you how warm you should dress, and for much of the year nobody in temperate parts would mind it reading a few degrees higher. But mere changing temperature is not the effect we’re worried about. What is alarming is the massive unbalancing of the world’s climate system that promises to result from it: the threat of catastrophes like the BC pine beetle infestation occurring on a global scale. (Sadly, now that “global warming” has been entrenched in the popular imagination, “climate change” and other descriptions for it get derided by skeptics as desperate rebranding.)
There’s no doubt that it will be impossible to prevent global temperatures from continuing to increase in the foreseeable future. But we shouldn’t underestimate the difficulty of adapting to the conditions that will come out of this, and we certainly shouldn’t rest in trying to prevent further warming. Funding for research in ecology, and application of its findings, will be crucial if we are to prepare ourselves for the fallout from the known and unknown changes we are causing on this planet — at the scale of provincial forests, and at the scale of the global climate.