... you could be in for a surprise. If, that is, you're not up on the latest climate research. Figuring out what role the forests will play in the Earth's climate regulating mechanisms have long proved more than a little tricky. And it just keeps getting more complicated.
Back at the turn of the century, for example, it was widely assumed that heavily forested countries would be in an enviable position when it comes to calculating net carbon emissions. Canada went to Kyoto negotiations in 2001 arguing that it should get credit for maintaining its vast boreal forests, because "everyone knows that they're carbon sinks" (or something more diplomatic to that effect).
Even then, forest biologists studying global warming knew that wasn't correct. Major studies had been appearing from the Hadley Centre in the UK and Duke University in North Carolina that suggested there's a big difference between tropical rainforests and higher latitude boreal forests. The former might continue to serve as sinks in a warming planet, but the reduction in albedo in northern Canada and Siberia could more than offset the sink because more dark trees absorb more solar energy than does white, reflective snow.
During a conference call interview with Canadian negotiators back then I asked about the conflict between the new scientific findings and the official Canadian position, but got only the polite equivalent of a blank stare. So it was clear there was a problem.
At about the same time, I wrote a story on an emerging threat to Canada's western forests in the form of a little critter called the mountain pine beetle. Normally a manageable pest that was killed off in the winter, the recent warming trend that some blamed on El Niño was letting them survive from year to year, and the growing populations were chewing their way through vast stretches of loggable trees.
Back then, scientists were not that keen to associate the problem with climate change. Here's the tail end of my story:
There are now fears that if the warming trend continues according to the predictions of global climate change models, pine beetles could migrate into northern B.C. and even the Yukon, regions now beyond the insect's tolerance levels. As Hall points out, some organisms are extremely sensitive to temperature changes, and "one or two degrees change in climate can make a huge difference to insects."
[Les] Safranyik [Canada's chief pine beetle expert] cautions that we need much more data before linking a warming climate with increased pine beetle attacks. "Even during so-called normal conditions, 20 or 30 years ago, some years with mild winters and warm summers, we'd see beetles 80 to 100 kilometres north of their normal range," he says.
More than eight years later, the data are coming in. From Nature's news section:
The coniferous forests of Canada, Finland, Russia and Sweden that make up the boreal region are expected to experience more warming than forests in the equatorial zone. Although warmer temperatures could initially fuel a northward expansion of the forest, the short-term positive impacts would be cancelled out by damage from increased insect invasions, fires and storms.
The shift from sink to source is already happening. The mountain pine beetle has devastated the forests of western Canada. The outbreak currently covers 14 million hectares -- roughly 3.5 times the size of Switzerland, says Allan Carroll, an insect ecologist with the Canadian Forest Service in Victoria, British Columbia. By 2020, the projected end of the outbreak, about 270 megatonnes of carbon will have been emitted to the atmosphere. "That's the equivalent of five years of emissions from the entire transportation sector in Canada," says Carroll.
The new research is being reported this week at an a UN conference. The bottom line is, if greenhouse gas emissions aren't brought down soon, "forests will have difficulty adapting to climate change" and could be transformed from carbon sinks into sources. This is one of those thing that everyone should be worried about.
Nature's Hannah Hoag ends on a upbeat note, although some might say her source is stretching in search of a positive spin:
Carroll thinks that some governments are now ready to listen. "The mountain pine beetle outbreak and the climate signal associated with it is the canary in the coal mine about future disturbances. It's caused jurisdictions to perk up and take notice," says Carroll.
It would be a good thing if Carroll is right. I'm not sure Canada's current government is any more prepared to accept the science than its predecessor was in 2001. Consider these thoughts about climate policy in Canada from one of the country's most astute political columnists, Jeffrey Simpson:
In Ottawa, the [Stephen] Harper government increasingly has no policy, but is just waiting to latch on to whatever emerges in the United States. Waiting for Obama is the way to describe the Canadian position....
With Ottawa having abandoned any pretense of having its own policy, and Alberta stubbornly divorced from emerging North American (and world) realities, Canadians can only wait until their country's policies are framed in Washington, after which they will have no choice but to act.
That's what happens to a country without a serious national policy and to a one-party province shaped by too many illusions.
I'm not sure where people get the idea that tropical forests behave differently. One of the best long term ecological studies suggests a small increase in average temperature might reach a tipping point where tree mortality would increase and grasslands would begin to replace tropical forests releasing all that carbon dioxide from their woody storage.
D. A. Clark, S. C. Piper, C. D. Keeling, and D. B. Clark. 2003. Tropical rain forest tree growth and atmospheric carbon dynamics linked to interannual temperature variation during 1984-2000. Proceedings of the National Academy of Sciences, 100: 5852-5857.
You should also look into the BOREAS study in the early nineties - a four year joint study between the US and Canada. Pretty darn big project, probably with >$50 million budget. The collaboration produced more than 400 papers and had tons of collaborators. Scientifically, it was an uncontested success and set a precedent for the similar protocol in Latin America.
Funny thing was BOREAS came back saying that the boreal forest was not as much of a sink as originally thought (i.e. tropical levels) and also could have potential to be a source. That was not what was expected. So, the findings were ignored by government. In 1999 the Canadian senate commissioned a report on the state of the boreal forests and not one of the 400+ papers from BOREAS was cited.