Excess Death & Heat Waves (Part 1)

A fruity response to the BBC headline that record UK excess deaths occurred during summer heat wave

Beneath a title of Record Excess Deaths In UK's Heatwave Summer etched in alchemical tones of blood red, black and deathly white we learn from auntie beeb that the UK endured record high temperatures of 40°C this summer, with around 3,000 more deaths than expected in England & Wales. Talking heads assure us that we see more deaths during periods of high heat and that climate change is almost certainly the cause for folk dropping like flies this year rather than anything experimental and pharmaceutical. With another jobbette done by the ONS/UKHSA we can all relax and go about our business safe in the knowledge that fossil fuels are to blame.

It’s that old chestnut of causation and correlation, innit? Well, with several years of climate analysis under my belt I couldn’t resist having a peek under this particular bonnet so here’s my plat du jour, complete with garlic croutons and Caesar side salad.

Heat Wave Periods

There are a number of ways we can assess the impact of heat waves on human beings, starting with measures of temperature itself. We can look at daily maxima as well as daily means and we can look at weekly maxima, and mean weekly maxima as well as weekly means. We can also ignore how hot it actually got and count the number of days a certain temperature threshold is passed. We may call these heat wave periods, and analysis of these will give us different answers to analyses based on actual temperature measurements.

We should note the ONS/UKHSA prefer to use heat wave periods as defined by the number of days the Central England Temperature Record (HADCET) daily mean temperature exceeds 20°C. That doesn’t sound like a lot but we must remember these are mean daily temperatures with only 797 days meeting this criterion over the 91,584 days covering the period 1st January 1772 – 30th September 2022 (0.9%).

If we sum heat wave periods by year since 1772 we arrive at this glorious slide: