This summer we haven’t just had heat waves, we’ve seen them plaguing vast areas around the northern hemisphere. Intense heat in Sweden sparked an epidemic of wildfires in their drought-stricken forests, so bad that they had to ask other nations for help. A dozen of the wildfires were in the Arctic circle, no less.
Ouargla, Algeria noted the highest reliable temperature ever recorded in Africa at 51.3°C (124°F). Kumagaya, Japan saw the highest temperature ever recorded in Japan at 41.1°C (106°F), while the death toll hit 30 and thousands more needed hospital treatment for heat-related conditions. California broke so many temperature records in their heat wave that increased use of air conditioning caused power shortages. In Britain, the heat melted the roof of Glasgow’s Science Centre, and caused a garbage truck to get stuck in — not on, but in — the road when the asphalt melted.
Perhaps most unexpected, a blistering heat wave in Canada (yes, Canada!) has filled Montreal’s morgue with the bodies of those who died from the heat; many corpses had to be stored elsewhere in the city. Montreal coroner Jean Brochu said it was first time the city’s morgue had been overwhelmed this way.
The U.K. Guardian has an excellent report on the story. It points out that part of the reason for the global oven is the jet stream, which has been “stuck” in a wavy pattern which makes systems linger so long that the heat becomes unbearable. But it’s not just the jet stream; that has happened before. What makes this worse, noted Tim Osborn of the Climate Research Unit in the U.K., is that “The baseline on which these effects operated is very different today. Since 1976 we have had several decades of global warming — caused by rising carbon emissions – which has raised baseline global temperatures significantly.”
Even the stuck jet stream may be linked to man-made climate change. Mann et al. (2017) note that such events are linked to “high-amplitude quasi-stationary atmospheric Rossby waves,” and that climate change favors conditions of “quasi-resonant amplification (QRA),” possibly linked to amplified Arctic warming. So — not only are extreme heat waves worse because of man-made global warming, they may also be more likely because of man-made climate change.
The link between climate change and changes in the behavior of the jet stream is still tentative; as Mann et al. say, “Both the models and observations suggest this signal has only recently emerged from the background noise of natural variability.” Even if not, heat waves are still more common and more severe because of global temperature increase.
It may take another decade or even longer for such associations to be established definitively. This much is certain: the consequences are deadly. Can we afford to wait and see?
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