Most people are already aware of the major heat waves the world experienced in August of 2022, but not many know about the increase in river heat waves. This increase in river temperatures has been going on since 1996, a recent study shows.
A river heat wave is when there is an abnormal increase in the average temperature of a river for more than 5 days. The study specifies that, for the increase in temperature to be classified as a river heat wave, it must exceed the 90th percentile of the local average temperature.
Since 1996, river heat waves have seen an increase in frequency, intensity, and duration of the events. The average duration of a river heat wave in 2021 was 25 days, which is more than double the 11-day measurement from 1996.
There is a multitude of reasons that the heat waves have been increasing, but it can be mainly attributed to global warming, less rain, and a decrease in water flowing through rivers in the United States. These rivers heat up faster because the air around them is hotter and there is less water to heat up.
Unfortunately, many river-dwelling animals, such as salmon, are sensitive to spikes in temperature. The elevated water temperatures decrease the oxygen content of the rivers, which can significantly decrease the population of these creatures. According to The Conversation, “This year’s hot and dry summer could collapse the salmon fishery in the Sacramento River in California. In British Columbia and Yukon, salmon numbers have declined by as much as 90 percent.” Animals aren’t the only life form that are being affected by these heat waves; plants are being affected too. Not only is this bad for river ecosystems, but it is also damaging to the fishing industry.
The effect of these heat waves may affect us for years to come. Mr. Bonnar, Head of the Léman Science Department, says, “Recent implications of ecological changes are things like toxic algae blooms in more stagnant water and certain animal species no longer existing.” Changes in smaller ecosystems impact larger ones, which eventually start to affect humans. If the rise in severity of river heat waves continues, it will threaten the balance of river ecosystems, and potentially the wild-caught fishing industry.
The future of the climate may seem bleak, but, unlike some parts of climate change, we can help decrease the frequency and severity of river heat waves. Planting trees that shield natural running water is proven to help reduce the temperature of the river. However, actions must be taken to slow the increasing severity of these heat waves, as humanity could be facing another ecological crisis in riverine life.