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The Local Impact of a Changing Climate

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Summary: Apart from the debate about why climate change might be occurring is the reality that it is actually occurring. Important changes to the climate have been felt locally this past year, most dramatically from the rainstorm in late June. But there is something larger going on that many locals, especially those that have only been in the valley for a relatively short time, may not have noticed.

When I was a kid the worst storms of the year tended to come in the winter, and would always originate out of the South-East. This small detail is important so hang onto it as you read on.

First, a little context for you. I was born and raised in Calgary, and am nearing fifty now.  When I refer to myself as a kid, I think of my life from two to ten. Later, you can do the math to apply the rest of this discussion to a timeline of your own making.

The prevailing weather in Calgary has always been from the west (in my life), making the region famous for another weather phenomena, the Chinook. Predicting the weather in Calgary has always been a simple matter of looking to see what the air mass in Vancouver is doing today, calculating its speed over the ground to determine when it will arrive here after climbing over the mountains of western North America, in particular the Rockies. That is important to understand because the Rockies modify the air mass as it is first lifted up (cooling and drying out in the process), then comes crashing back down (heating up and accelerating) as it moves across the lee slopes of those mountains. This has always given the Calgary region relatively warm weather most of the time, in particular drying out and carrying away snow during the winter. The wind is not normally called a Chinook in the summer-time, but it is technically the same flow just not as noticeable (warmer) as it is during the winter.

Except for those occasional winter-time storms, Calgary’s weather has always been dominated (again, during my life) by a westerly flow for about 340 days every year. Until this past year, when a simultaneously subtle and dramatic change seems to have taken place. I am only estimating here, but I would say that 340 of the last 365 days have been dominated by an upslope, or easterly flow of air. In my life (one metric for a geologic era), this has never happened before.

In most years the air mass Calgary sits beneath is something meteorologists would call Maritime Tropical and Maritime Polar. Once in a while a big system would push down from the north, originating from air masses named Maritime Arctic, or Continental Arctic. These would only ever happen during the winter, with lows bringing cold wet maritime air in, and highs bringing cold dry air in. Then once or maybe twice a year, a big winter storm would come in from the south-east bringing with it a mixture of air masses that originated from the great plans of the United States, otherwise known as a Continental air mass. This was the weather when I was a kid and for most of my adult life.

Forgive me now the terms I have just used. As a pilot I was taught to consider the weather in slightly different terms than the weatherman you might listen to would use during the evening news hour. Fronts are the element of weather they focus on and these result from what the air masses are doing. Fronts are the immediate weather that will pass through later this afternoon. I am simply looking at this in a different scale, so the language differs.

I have noticed lately the local weather guys seem to be having difficulty predicting what will happen tomorrow.  A couple of times this past year I went to bed around eleven after having one last look at the interweb, which said nothing of imminent weather. Then, rose from bed in the morning to see 20cm of fresh snow on the deck and a message on Environment Canada’s website stating ‘Heavy Snowfall Warning Ended’ within a green banner. How could they not see this coming?

One of the fundamental elements of weather forecasting in computer models is something described as persistence, and there are layers to this. Firstly, what you see today is likely to be what you will see tomorrow, unless there is a major change in the presently prevailing air mass. Second, averages for this day influence what we should expect to see tomorrow too. If it was an average of fifteen degrees on this day calculated over the last hundred years, then it will probably be somewhere close to that tomorrow. But the computer models with their century of history have all suddenly become irrelevant because of a fundamental change in the air mass that has traditionally influenced our climate in this region.

During most of this last year there has been a noticeable (but mainly gentle) upslope flow of air that has continental origins. The usual westerly flow has been almost entirely replaced with this continental air mass, and the weather people no longer have the data they need to be able to look more than about twenty-four hours, or perhaps forty-eight hours into the future anymore, and the result is new weather, and unpredictability.

Flooding in downtown Calgary this past spring was entirely the result of a massive upslope flow of air that came into the region from the south-east, previously a winter-time only event. The same air mass climbed up into the Rockies just to the west of the city and unloaded a massive pool of water as it cooled and condensed in the basins of the mountains, then roared back downhill again carrying away everything in its path.

This is climate change. Tangible, and visible for everyone to see. Debate if you still want to why it is occurring, but that it is occurring is difficult to argue and if you have not already made a few adjustments; you will need to get started soon because this new weather paradigm is not going away in our lifetimes. Even if you stop driving your Humvee (reduce emissions) the climate will still change, as it did during the last interval between the two most recent ice ages. As the climate changes weather will vary around the world, but locally, it apparently means warmer winters (I do not believe it went below minus thirty even once last year, and it certainly never got anywhere close to minus forty, something that used to occur for at least a few days every winter), more intense rainfalls in the late spring, and more frequent and severe thunderstorms in the early summer, along with their associated hail and tornadoes.

Climate change will mean nearly two billion people world-wide will need to move uphill about two hundred feet during the next one hundred years. A big deal if you live in a place like New Orleans, where it is necessary to travel about four hundred miles in order to get two hundred feet above sea level. Most of the biggest cities in the world are impacted by this reality.

If you are wondering now how warm it will eventually get, we are still about ten to twelve degrees cooler than during the last gap between ice ages. There was probably no Humvees back then either, so you may expect that climate change will occur no matter what we drive, or how we live. As occupants of the planet we might be affecting how quickly the change is occurring, but it would be a mistake to believe this is reversible.

Sea-side cities like New Orleans are obviously (now) not the only places that will be affected by the change in our climate. All of Calgary is built on a massive deposit of gravel, and the upwelling of water that occurred this past spring could occur anywhere in the city, not just downtown. In Canmore, the residents of Cougar Creek cannot deceive themselves into believing this was a one in a hundred year event. Since that sub-division has been built (about two decades now) that creek has swollen into a raging river on at least four different occasions. In fact the entire sub-division is built on a large alluvial fan that drains away from the bottom of Cougar Canyon. I remember this. I walked around up there before a single home was put in. Lots were being sold for just $1400.00 apiece at the time, but I would not buy one. Building all those houses across that fan was either very short-sighted, or incredibly naïve about what would happen with the water that so obviously poured forth from Cougar Canyon from time to time. The population in Canmore was about twenty-five hundred people then. Over the course of just a couple of decades, a blink in geologic terms, even my own geologic era, this entire town has been transformed by development. This development begs many questions, but the most immediate ones must now address this new climate reality.

The province recently proposed a framework that would begin rolling back development in flood-prone areas, and preventing it altogether in such zones going forward. This is a good first step, but a new planning vision is needed immediately that addresses this need for the next hundred years, and more. The municipality should be offering safe lots for free in exchange for those originally sold in flood prone areas. Here, and in High River, and in Calgary too. The province should be rebuilding homes in new locations for people as they lose them. Not to some arbitrary basic standard, but to replacement quality. They must do this because the municipality, and certainly the province knew better twenty-five years ago. They are equally responsible, and must now step up to mitigate the losses, fix the problem, and begin acting to prevent this from recurring over, and over again.

 Flood

Cougar Creek, Canmore, June 21st 2013

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Written by snappledagain

12/09/2013 at 09:59

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