Our cultures and economic systems are structures of habit. We build them around predictability: that our salmon will return from oceans to rivers, our fields will produce food, our land will grow forests, the sun and rain will come at their appropriate times. Each civilization has its own set of necessities provided by its local ecologies. Change these ordinary, natural events and an entire set of uncertainties is created.
Consider, for example, Rivers Inlet, a remote place on the west coast of BC that once had the third-largest run of sockeye salmon after the famous Skeena and Fraser Rivers. Years of environmental abuse from overfishing and logging near salmon streams eventually reduced the size of the run. During the 1970s, sockeye returns became unstable. Despite tightened constraints on fishing, the stocks continued to fall. By 1996 the decline was significant enough to warrant a complete commercial closure. Still, the run continued to fall, until the crash of 1999 when returning fish were counted in thousands rather than hundreds of thousands. What happened?
This is the subject of research by Desiree Tommasi, a graduate student in biology from Simon Fraser University (The Vancouver Sun, Oct 9/07). Her hypothesis is that climate change is altering the delicate ecological factors that accommodate the survival of the out-migrating juvenile sockeye. Warmer weather and greater precipitation ‹ the measurable consequences for coastal BC of rising levels of atmospheric carbon dioxide ‹ are altering the amount and the timing of freshwater flowing into Rivers Inlet. The "nutrient-poor, often silt-laden layer of freshwater on the surface of the Inlet," she writes, "shifts the structure and timing of the food web." The phytoplankton bloom is delayed, the zooplankton do not grow, and the juvenile salmon arrive in the salt water on schedule to discover they have nothing to eat.
The same loss of co-ordination is being blamed on reduced survival of coho stocks in the Strait of Georgia. And changes in ocean ecologies caused by global warming are creating other unpredictables. Warmer water, different currents, altered upwellings and newly arrived southern predators are all conditions that can be unfavourable to salmon survival. Indeed, we are now witnessing structural shifts in the Pacific Northwest marine ecology that will eventually reshape our West Coast lives.
Consider the effects on some of Vancouver Island's rivers because of the dry summer of 2006. Without the usual autumn rains, the Cowichan was so low in September and October that about 1,000 chinook had to be trucked 45 km to their spawning grounds ‹ a first for BC, and perhaps Canada. Many of Cowichan Lake's feeder streams went bone dry. The Chemainus River was reduced to a few isolated pools. For east Vancouver Island and 23 sites around the Georgia Basin, plans are now being made to store water for release in droughts. Many salmon conservation groups are already trying to drought-proof fish-bearing streams. Craig Wightman of BC's Ministry of Environment says ominously, "Welcome to climate change." Adds Al Lill of the Living Rivers - Georgia Basin project, "We expect to get the 50-year droughts now about every two or three years and 100-year droughts probably every five years. The trend lines we are seeing show climate change is upon us, it's with us now." (Globe & Mail, Oct 29/07).
In BC's interior, the devastation from the mountain pine beetle is directly linked to a warming climate. The little bug has set in motion ecological consequences which we are just beginning to measure. A collapsing interior forest industry is obvious. But we now know that the massive loss of tree cover, combined with the general warming trend, will increase river temperatures, which will downgrade salmon survival. Even without the help of the pine beetle, the Fraser is already 1.1°C warmer than it was four decades ago. The loss of interior forest cover will also cause extremes of spring run off, sending elevated flood threats throughout the Fraser Basin, all the way to highly populated centres in the Fraser Valley and Vancouver. Additionally, the pine beetle is converting some of the province's southern forests to permanent grasslands.
In the prairie grasslands of the US, ranchers have been complaining about the encroachment of woody shrubs into areas used for grazing cattle. Department of Agriculture officials blamed bad ranching practices. Now they know better. Rising levels of atmospheric carbon dioxide favour the growth of woody plants such as fringed sage. Experiments show that present levels of CO2 produce a 40-fold increase in the growth of these plants over grass (The Vancouver Sun. Aug. 28/07). Jack Morgan, the lead researcher in the study, says that such "an increase in biomass is huge", and this explains the "slow invasion of woody shrubs [that] has been happening for up to 200 years." Elk and antelope will eat these shrubs but cattle won't. So we encounter yet another surprise that will force us to change our customary behaviour.
The effects of elevated levels of carbon dioxide on plants are now easy to conduct in many US cities because these urban centres have already reached the global climate conditions predicted for future decades. Cities are typically 2° C warmer than countrysides, and the present atmospheric CO2 levels of 382 ppm ‹ probably the highest in 20 million years ‹ far exceed the pre-industrial levels of 280 ppm. Baltimore frequently reaches 450 ppm, Phoenix 550 ppm and New York can climb to 700 ppm. In these conditions, poison ivy produces more potent urushiol, the oil that causes us the burning irritation, and a common allergen such as ragweed can grow three to five times bigger and discharge 10 times the volume of pollen (Newsweek, June 4/07). Toxic molds and fungi grow better in elevated CO2 levels.
So do many of our food crops. Unfortunately, at the higher temperatures that accompany climate change, they also lose their ability to pollinate. But that's the subject of another surprise.