Canada’s floods after the summer heatwave show how climate disasters can cause additional damage

British Columbians will feel that they have experienced more climate disasters than their fair share in 2021. In November, intense rain storms swept through western Canada after a record-breaking heatwave. It’s also likely the long-lasting effects of the heatwave made the results of the recent rainfall worse, causing more landslides – which have destroyed highways and railroads – than would otherwise have happened.

In June 2021 the western North American temperature records were broken. The British Columbia town of Lytton registered 49.6°C, breaking the previous Canadian national record by 5°C. The unprecedented weather was caused by a high pressure system, a so-called “heat dome”, which sat over the region for several days.

As the high pressure compressed air, heat intensified inside the dome. Because there was less water being evaporated to cool things down, temperatures were even higher in dry ground conditions. Although unconfirmed, it’s estimated that the heatwave caused over 400 deathsOnly in British Columbia

Wildfires were also started by the dry and hot weather. Lytton recorded the hottest ever national temperature just days after it was recorded. burned to the ground. The summer’s fires and drought left the ground charred and barren, incapable of absorbing water. Because the soil cannot be held in place by the tree roots that have been damaged, landslides are more likely. It prevents water from soaking into the baked ground and allows water to flow over the soil faster.

The huge rain storm which lasted from Saturday November 13 to Monday 15 was caused by an atmospheric river – a long, narrow, band of moisture in the atmosphere stretching hundreds of miles. This band can cause extreme rainfall if it crosses over land. In 48 hours it did. over 250mm of rainIt was located in Hope, 100km east Vancouver.

This amount of rainfall would likely cause severe flooding on its own. The combination of the dry soil and the rainfall has led to catastrophic results. Landslides have destroyed many of the region’s transport links, leaving Vancouver cut offBoth rail and road. But the bad news doesn’t end there; sediment washed away by these floods could make future floods this winter even worse.

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How an ‘atmospheric river’ drenched British Columbia and led to floods and mudslides

British Columbia is currently in the grips of a compound climate catastrophe, according to scientists. One extreme weather event, such as a heatwave, can magnify the effects of another, such as a rainstorm. Instead of seeing floods, wildfires, and other extreme weather events as separate events we must understand the chain of crises that will likely increase as the planet warms.

How to understand the effects of compound climate disasters

Vancouver is home to the busiest in CanadaMoving cargo worth US$550 million every day. Ships carrying commodities are now stranded offshore because of the damage to rail links. Canada’s mining and farming industries are having to divert exportsThrough the US. Significant economic impacts can be possible depending on how quickly rail links are restored.

The June heatwave, and the November rainstorm are both record-breaking, unprecedented events. But is it just bad luck that they occur in the same year, or are they both record-breaking? The heatwave was quickly attributed to virtually impossibleWithout climate change. The atmospheric river that brought the deluge will likely also become more common and intenseIn a warmer climate.

Future flooding in British Columbia is almost certain more frequent and severe. This is life. 1.2°C above the pre-industrial temperature average, yet most politicians don’t seem too worried about taking the necessary action to prevent warming beyond 1.5°C – the limit which countries agreed in 2015 is a threshold beyond which catastrophic climate change becomes more likely.

Western Canada’s year of weather extremes did not come from nowhere. Past trends future projectionsWe can expect to have warmer summers and drier winters in this area of the globe. record-shattering climate extremesThese are on the increase.

As climate change accelerates, compound climate catastrophes are becoming more common worldwide. Risk assessments typicallyThe impact of one event can be measured individually, such as the damage from intense rainstorms. However, it is important to take into account how the drought before it influenced it. This causes scientists and insurance providers to underestimate the total damage. With so many combinations of climate extremes – flooding following wildfires, hurricanes passing as cold spells arrive – we must prepare for every possibility.