Climate change and the effect on B.C.'s rivers

The Alouette River – which feeds the 9-megawatt Alouette Generating Station – is mainly driven by winter rains but has a snow melt component in the spring. Under future climate changes, the Alouette might be fully driven by rainfall.

Posted by Sean Fleming

Greenhouse gases are an example of too much of a good thing.

Although naturally occurring greenhouse gases like carbon dioxide are a necessary ingredient for life as we know it, certain human activities – carried out long enough and at a large enough scale – can put so much extra greenhouse gases into the atmosphere that they can actually change the global climate. Because the hydroelectric power generated by BC Hydro comes from rivers rather than fossil fuels, we're ahead of the game.

But just because we're not contributing much to climate change doesn't mean that we don't have to deal with it. Climate change could affect the river flows that drive our hydroelectric generation, and BC Hydro is proactive about understanding and adapting to those changes.

Scientists have known for decades that greenhouse gases like carbon dioxide, methane, and water vapour can warm up a planet. That's part of the reason why life exists on Earth. Without the warming effect of these natural atmospheric gases, the average surface temperature of our planet would be about 30°C colder – way below freezing, and too cold to support life as we know it.

So how has modern civilization meddled with that balance? Two effects of global economic and population growth are the main culprits. On the one hand, the combustion of fossil fuels – to drive cars, heat homes, and power factories – adds another source of greenhouse gases. On the other, deforestation removes a sink for those gases.

Hydroelectric dams generate electricity by feeding water through turbines, rather than by burning fossil fuels – and because the vast majority of British Columbia's power is hydroelectric, we're pretty green as far as greenhouse gas emissions go. But climate change will be coming anyway, and that could change environmental conditions like temperature, glacier retreat, how much and when it rains, and whether precipitation falls as rain to run off to rivers right away or instead falls as snow to be stored until the spring melt. And those changes might in turn affect the amount and timing of flows into our reservoirs, potentially impacting power generation.

To be sure, climate and river flows vary for completely natural reasons. For example, Vancouver was under a kilometre-thick ice sheet about 12,000 years ago, millennia before the industrial revolution. But the speed with which modern human behaviour is changing the global climate, according to climate scientists, may be unprecedented in geologic history. And though it's silly to blame every damaging weather event on climate change, there's a strong consensus within the scientific community that the ultimate effects of those broader climate changes could be enormous.

BC Hydro's Hydrology and Technical Services Group has been working hard to assess what the impacts will be. We're tracking the work of the wider scientific community, doing our own internal research and development, and supporting external research through funding and in-kind contributions. For example, we're strongly supporting the Pacific Climate Impacts Consortium at the University of Victoria, and the Western Canadian Cryospheric Network, based at the University of Northern British Columbia.

It looks like the most likely impact of climate change to our reservoir inflows has to do mainly with the timing of river flows, rather than the total amounts – so the way in which our dams will be operated may have to change, but the total capacity probably not so much. Still, these studies aren't complete yet, and we'll have to see what turns up.

We'll keep you posted.

Sean Fleming works in BC Hydro's Hydrology & Technical Services Group, where he does river forecasting and serves as a climate change subject matter expert, and is an adjunct professor at the University of British Columbia.