Rain and flooding isn’t all that unusual in Alberta but what was different on this occasion was that it rained so much over just one area, and the reason for this was that the weather system that brought the rain became trapped over Alberta. Instead of having a long track and depositing the rain over a wide area, it became concentrated in one place.
To the north was an area of high pressure and this prevented the rain moving northward, to the west were the Rockies and they prevented movement in that direction and all the while the winds were coming in from the east and blocking any escape in the direction.
When the rain fell it did so onto already wet ground following earlier rain, the ground was unable to soak up the excess water and it readily flowed downhill and overwhelmed the streams and rivers. This was compounded by the fact that the ground is still frozen at the higher altitudes and the rain that fell there wasn’t absorbed by the ground either.
What we need to be careful of is blaming a specific weather event on global warming and we have to ask if such an event could have occurred if there were no warming, and in this case the answer is yes it could have.
Instead of singling out one weather event, we need to look at the larger picture and compare what’s happening now with what happened in the past and see if there’s been any changes. There have.
Extreme weather events in Alberta tended to be fairly rare and according to the Insurance Bureau of Canada annual losses averaged around $100 million (CAD), this was up until a few years ago but in recent years the average loss has been $670 million a year.
Just recently the IBC commissioned the Institute for Catastrophic Loss and Reduction to conduct an investigation into how climate change was affecting Canada, both now and in the future.
The report found that there has been a significant increase in most types of extreme weather events including droughts, floods, excessive heat and intense rainfall; leading the IBC’s President Don Forgeron to state that “Alberta has become the place where bad weather pays a visit more often”.
Somewhat prophetically the IBC warned less than a month ago that “Rainstorms, when they come, will be more intense and could cause flash-flooding in low-lying areas and overwhelm existing storm sewer systems.”
In summary then, global warming is affecting Alberta and there has been an increase in the number of abnormal weather events, but we can’t blame global warming as being the cause of the recent flooding.
Regarding the Arctic, this is the part of the world that has warmed more than any other and it’s of critical importance to global weather patterns. In recent years the Arctic weather has become ever more disrupted and at times has gone into a complete reversal of normal patterns, this has a major effect on Canada.
Normally the Arctic is dominated by two weather systems – anticyclonic (high pressure) over Canada and cyclonic (low pressure) over Siberia, this sets up a pattern of wind blowing from Canada into Siberia. Since 2000 this system has been revered on about eight occasions and when that happens it causes severe weather disruption throughout the Arctic and surrounding areas (Canada, Northern Europe, Greenland, parts of the US).
The Polar Jet Stream is also becoming increasingly disrupted and in recent years has meandered from it’s predictable path. The jet acts as a barrier trapping cold air to the north of it and warm air to the south, it blows anticlockwise around the upper latitudes and pulls along weather systems in its wake. The disruption has led to unusual weather in many parts of the world and has been a significant contributor to many of the worst weather disasters in recent years.
"For one thing, Alberta is too high above sea level, so no, it is not because of the melting polar ice cap."
Climate "Realist" falls all over himself trying to show he is a "mderate". I'm surprised he did not find some way to trash Al Gore.
The correct asswer is that the melting of the ice caps plated a role, but an extremely small role. The Earth is a tiny bit hotter because there is less ice to reflect radiation out.
For one thing, Alberta is too high above sea level, so no, it is not because of the melting polar ice cap.
They never had floods in Alberta before?
I think that is all just part of it being the summer time.
We have all seen the reports of severe weather events in the southern states each year. Now we are starting to see more of this in Canada and the recent flooding in Alberta and severe weather is an example of this. Could this be the result of the melting and receding polar sea ice cap? Could we be in store for more of these events?
