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Water Today Title January 18, 2021

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Update 2018/2/23


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By Stuart Smith

"I'm scared. People are already fighting." I'm talking to Kristy Charlton, an elementary school teacher and resident of Cape Town, South Africa, which is suffering the effects of a three year drought. "I even hear my Grade 1s, who can hardly form sentences, talking about being in a drought. There's no one I know who has no clue."

The dire water situation has overshadowed life in Cape Town for the past year, but this summer, in January, they reached Level 6b. There is no level 7. The next step - ominously dubbed 'Day 0' - is when water is cut off to the city. If that happens, everyone will have to queue for a daily 25L ration of water at standpipes across the city.

What Cape Town's drought shows is that even a large, modern city can be brought frighteningly close to catastrophe with an unlucky combination of poor weather and questionable management. For comparison, Cape Town made $58.9 billion in 2014 and in the same year, Ottawa made $58.2 billion. If even wealthy cities are vulnerable to water shortage, and with climate change already happening, could a Canadian city be next?

Barrie Bonsal, a research scientist at Environment and Climate Change Canada (ECCC) specialising in water science and technology, explained to me the science behind climate in Canada and how atmospheric changes could affect the future of droughts. Simply put, a drought occurs when there is more evapotranspiration (water going up) than precipitation (water coming down) over a given time period. To get a national picture of how Canada will be effected by the changing climate, the ECCC take various models based on a given level of global GHG emission, and take the mean result. What they have found, Barrie explains, is that on the whole, Canada will be getting warmer. This means greater evapotranspiration.

The precipitation factor is harder to predict, and is more locally variable than temperature. But Barrie says models lean towards a wetter climate.

Therefore, for a given time period and depending on how well humanity deals with global warming, we can expect greater evapotranspiration, and more precipitation. It is worth remembering these are not forecasts - there is a large element of uncertainty due to the complexity of climate and unknown feedback loops. Especially as we do not yet know when or if humanity will get a handle on climate change and whether temperatures will stabilise or start to come down.

If these changes evolve as expected, what does that tell us about the likelihood of drought? First, Barrie reminds me that droughts are natural, common occurrences in Canada. They have occurred in the past and will occur in the future. What is important for water management is to understand their changing nature going forward: how long they will last, where they will occur, at what time of the year they occur, and how they will change with increased global warming throughout the 21st century.

The 'where' is particularly important, as although it is possible to predict broad changes across Canada, it is much harder to predict regional and local changes. Even for a specific province, explains Gary Wheeler from Environment and Climate Change Ontario, the differences in climate change will be quite significant from region to region.

Barrie also stresses that you have to look carefully at when the rainfall occurs - not just the annual trend. Across Canada, summers are actually expected to be drier, with wet winters skewing the average to create wetter annual conditions overall. An important consideration when it comes to managing droughts.

For instance, there is the often overlooked situation of winter droughts, which has been part of the problem in the Western Cape. In Canada, although summer droughts are the most common and have the highest impacts, the right precipitation throughout all four seasons can be crucial.

A lack of precipitation in winter can create cold season droughts and the limited snowfall can have adverse effects. This is especially true in mountainous areas such as in B.C., where spring snowmelt replenishes reservoirs. Not enough snow in winter leads to less snowmelt, which could cause problems if the spring and summer are dry as well.

So what about cities like Toronto, where water is sourced from Lake Ontario and ends up back in the lake? Surely Lake Ontario is in no danger of drying up. Barrie was quite confident that you would never run out of water there, but low water levels can cause many other problems than a lack of drinking water. For instance, with transportation. If water levels become too low, even industries such as shipping could be affected. So much of our society relies on water being in the right place at the right time.

To help ensure that it is, we need to look at the other side of drought management - demand. The right management can make all the difference. The wrong policies and infrastructure can turn unfavourable weather conditions into dangerous supply problems. The right planning could be the key to whether residents, businesses, and farmers even feel the effects of the drought. What municipalities are doing to manage these climate changes, and how residents of Canada's towns and cities can help prevent a Cape Town crisis in Canada, will be explored in Part 2.


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