<
https://theconversation.com/statistically-impossible-heat-extremes-are-here-we-identified-the-regions-most-at-risk-204480>
"In the summer of 2021, Canada’s all-time temperature record was smashed by
almost 5℃. Its new record of 49.6℃ is hotter than anything ever recorded in
Spain, Turkey or indeed anywhere in Europe.
The record was set in Lytton, a small village a few hours’ drive from
Vancouver, in a part of the world that doesn’t really look like it should
experience such temperatures.
Lytton was the peak of a heatwave that hit the Pacific Northwest of the US and
Canada that summer and left many scientists shocked. From a purely statistical
point of view, it should have been impossible.
I’m part of a team of climate scientists who wanted to find out if the Pacific
Northwest heatwave was unique, or whether any other regions had experienced
such statistically implausible events. And we wanted to assess which regions
were most at risk in future. Our results are now published in the journal
Nature Communications.
Tracking these outlier heatwaves is important not just because the heatwaves
themselves are dangerous, but because countries tend to prepare to around the
level of the most extreme event within collective memory. An unprecedented
heatwave can therefore provoke policy responses to reduce the impact of future
heat.
For instance, a severe heatwave in Europe in 2003 is estimated to have caused
50,000-70,000 excess deaths. Although there have been more intense heatwaves
since, none have resulted in such a high death toll, due to management plans
implemented in the wake of 2003.
One of the most important questions when studying these extreme heatwaves is
“how long do we have to wait until we experience another similarly intense
event?”. This is a challenging question but, fortunately, there is a branch of
statistics, called extreme value theory, that provides ways in which we can
answer that exact question using past events.
But the Pacific Northwest heatwave is one of several recent events that have
challenged this method and should not have been possible according to extreme
value theory. This “breakdown” of statistics is caused by conventional extreme
value theory not taking into account the specific combination of physical
mechanisms, which may not exist in the events contained in the historical
record."
Cheers,
*** Xanni ***
--
mailto:xanni@xanadu.net Andrew Pam
http://xanadu.com.au/ Chief Scientist, Xanadu
https://glasswings.com.au/ Partner, Glass Wings
https://sericyb.com.au/ Manager, Serious Cybernetics
