Current Affairs

Is there a link between soaring temperatures and social unrest?

Increasing temperatures often mean increasing crime rates

While most Londoners welcome the prospect of a hot summer, it’s a different story for police on the streets. Not only must warm weather be much less enjoyable under a heavy stab vest and custodian helmet, if you look back at the worst moments of civil unrest in the capital in the last 50 years – the 1981 riots in Brixton and the events of 2011 that started in Tottenham – they all took place during the summer months.

You could argue it’s simply coincidence but commentators often link soaring mercury to uncivil behaviour. In Romeo and Juliet, Shakespeare wrote, ‘For now, these hot days, is the mad blood stirring’. More recently, in Spike Lee’s film Do The Right Thing, violence breaks out on the hottest day of the year. Is it poetic licence or does getting hot really make people’s blood boil?

According to National Police Chiefs’ Council lead for public order and public safety Chief Constable BJ Harrington, it’s impossible to overlook the link.

‘Historically, incidents of serious public disorder mostly take place over the summer,’ he says. ‘While not causal, there’s obviously a correlation. There’s a well-known saying: “PC Rain is out, so there’ll be no trouble today”.’

‘As the body directs more blood to the skin in an effort to cool off, you get more emotional reactions and less step-back cognitive processing’

Data from the London Metropolitan Police obtained by BBC Reality Check backs this up. Between April 2010 and June 2018, violent crime was on average 14 per cent higher when the temperature was above 20C than when it was below 10C. Harassment and weapons possession offences were each 16 per cent higher.

Looking at research, it appears the physical temperature of the brain is at fault. Speaking to Scientific American magazine, Glenn Geher, director of evolutionary studies at the State University of New York, says there really is something to the idea of being hot-headed.

‘Brain temperature, which is affected by ambient temperature, does seem to be associated with aggressive mood states and behaviour,’ he explains. ‘Bellicosity relates to a lack of oxygen in the regions of the brain that control our impulses, as the body directs more blood to the skin’s surface in an effort to cool off. So you get more emotional reactions and less prefrontal, step-back, cognitive-processing kinds of actions.’

There might even be a peak temperature for violence. Many criminologists adhere to a theory espoused in the 1953 film It Came From Outer Space: more murders are committed at 92F (33C) than any other. The reasoning? ‘At lower temperatures, people are easy-going. Over 92, it’s too hot to move. But at just 92, people get irritable…’

However not everyone agrees this applies to group behaviour. In The Guardian, Professor Chris Cocking from the University of Brighton says: ‘Describing riots in terms of individuals snapping doesn’t explain why crowds get involved.’ He points to winter riots like the Russian Revolution and believes the link between disorder and hot weather is much looser – people are just more likely to congregate outside in hot weather.

The reason for summer disorder could be simple. Chief Constable Harrington points his finger at other well-known trouble-making elements.

‘Longer days and warmer weather, can lead to greater incidents of crime associated with increased consumption of alcohol and more people being out in public,’ he says.

Indeed, nearly three in 10 Brits drink more alcohol when the temperature rises, and the market research company Opinium has calculated that warmer weather sees the country consume an extra 333 million pints of beer and 67 million more litres of wine. And we all know what can happen after a few too many drinks…

John Silcox is a freelance journalist