Why nobody is getting much done today

By mid-afternoon today, across an England under a red heat alert, a great many people will be sitting in front of a screen and achieving very little. Emails will go unanswered. Decisions will be quietly deferred. Tempers will fray in meetings that ought to have been calm. The instinct is to read this as a national lapse of willpower. The honest read — and the kinder one — is that it is biology, and the biology is remarkably well evidenced.

Start with what heat does to a working brain. A much-cited 2016 study followed young adults through a summer heatwave: those in buildings without air-conditioning were measurably slower and less accurate on cognitive tests than those in cooler rooms, with reaction time and throughput both falling by roughly a tenth. The effect isn't subtle, and it isn't about motivation. Once core body temperature climbs past about 38°C, both physical and mental performance degrade, because the body starts spending its energy on cooling itself rather than on the task in front of it. The International Labour Organization puts a figure on the physical end: in moderately strenuous work, output can fall by up to half once temperatures pass the low thirties.

This is not only an outdoor-worker story, which is the easy assumption. A study of 2.7 million firms across 23 advanced economies found that heatwaves substantially cut labour productivity across the board, and hit smaller firms hardest. Britain is one of those economies — and one conspicuously unbuilt for heat: housing designed to hold warmth in, offices without cooling, and a working day built on the quiet assumption that the weather is a backdrop rather than a constraint. The cost is not abstract: the ONS's experimental modelling puts hot days at around £1.2 billion a year in lost productivity across Great Britain, with the worst single year so far — 2020 — reaching a £5.3 billion hit, roughly 0.2% of GDP. The Health and Safety Executive has told employers plainly that extreme heat now threatens output, not only health.

That assumption is the behaviour worth watching. For most of British working life the calendar has set the day and the climate has been politely ignored. What today previews — and what a warming run of summers will make ordinary — is a world where temperature, not the clock, decides what people can usefully do between roughly noon and four. Hotter countries already know this: the long lunch and the early start are not laziness but adaptation. Across Britain this week, firms have quietly done the same — moving start times, sending people home, shifting heavy work to dawn — even as the culture still tends to read the instinct as a lack of grit.

Why it matters here. If you find yourself slow and short-tempered this afternoon and reaching for a story about your own discipline, the evidence says don't. The sensible answer to a 40°C day is to move the demanding, error-sensitive work into the cool of the morning and let the afternoon run light — not because you are soft, but because the morning is when your judgement is actually reliable. The larger question, the one sitting underneath this publication's whole subject, is what a working day looks like once we finally admit the body has a say in it. We may be about to find out, one heatwave at a time.

(Where this piece reads the studies as a guide to a single hot day, that is interpretation; the research measures populations, not any one person.)