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Karl Mathiesen is the eldest climate correspondent at POLITICO Europe.
Saturday was the hottest day of the year in London. I was celebrating my recent return to the UK with a loud and sweaty family dinner that went on well into the morning.
Unbeknownst to us, right outside our door, someone was bleeding.
As our guests headed home in the tropical night, they encountered a police officer who told them they could get through the crime scene barrier, as long as they walked around the trail of blood. And Monday morning, as I walked to my daughter’s new school, it was still there: 100 yards of little brown spots, sharp like coronavirus cells, embedded in the sidewalk.
Saturday was the sixth day in a row that London experienced temperatures above 30 degrees Celsius. Climate change has played a role in this heat. But was it just a coincidence that this sign of violence appeared on our street on the hottest day of what is shaping up to be the hottest year on record?
The link between violent crime and heat is increasingly established. Murder, sexual crimes and assault have been shown to increase when temperatures are higher, according to a research summary published in the medical journal Lancet.
A multi-city study in the United States found that the rate of intentional homicides in New York and Chicago increased by 9.5 percent with every 5 degrees Celsius jump. Ambulance logs in Japan showed a perfect linear relationship with temperature across tens of thousands of calls for assault injuries. And in Madrid, the rate of murder or assault of women by their partners increases when the temperature exceeds 34 degrees Celsius.
We also feel it throughout history. The UK inner city riots of 1981, 2001 and 2011 all took place in much warmer weather. In fact, preparing for summer unrest is part of police strategy in much of the world. There’s a reason director Spike Lee placed “Do The Right Thing,” his 1989 film about race-fueled violence in Brooklyn, on the hottest day of the year.
There are currently two main theories seeking to explain this link between weather and crime. The first is that the heat literally drives us crazy. The brain works differently when we are hot. We become more aggressive and lose our restraint. From outright violence to car horns, researchers have for decades drawn links between extreme heat and all kinds of aggressive behavior.
But this theory does not explain recent findings that increased violence occurs even when the temperature changes from cold to hot, meaning there is little physical or psychological discomfort.
For this, some scientists have proposed “routine activities theory”, which places more emphasis on how unusually warm weather interrupts our normal routines, putting people in places and situations, often outdoors from home, where they are not normally found.
The link between heat waves and climate change is simple. We are experiencing longer and warmer extremes, especially in Europe.
But when I contacted the press office of the Metropolitan Police Service, their response was one of bemusement. “This seems odd for POLITICO’s climate correspondent,” said spokesman Josh Coupe, although in the past London police have periodically warned their political handlers about the risks of a turbulent summer if the weather is particularly hot .
Coupe implied that I was a local fool trying to use media privileges to gossip. And in a way, he was right. Climate change has voyeuristic traits. It permeates everything. But for most of us, it remains largely in the background.
So it seemed a bit ridiculous, in the face of a shocking and undoubtedly complex act of neighborhood violence, to consider how the carbon dioxide composition of the atmosphere might have been involved. Trying to live fully aware of climate change requires a mindset reminiscent of paranoia – once you really look, it’s everywhere – unless, of course, it’s actually happening.
Often the connection between climate change and real events is reduced to a conversation about attribution, the ability to say something statistically significant about the role it played in a weather or other disaster.
And science becomes more and more agile with each passing year. As I write, an email has arrived from the UK’s Science Media Centre, explaining how the floods in Libya – which caused dams to burst and perhaps 20,000 deaths – were fueled by the overheated waters of the Mediterranean. Extreme events like this are often quickly followed by analyzes that tell us how much more likely such events have become because the planet is now 1.2 degrees warmer than it was a century ago.
But even then, are the dead and missing from Derna victims of climate change, or were there other major factors? For example, have the dams not been adequately maintained due to the intermittent civil war in which the country has been locked since the ouster of Muhammad al-Gaddafi?
What will science ever be able to meaningfully say about why a person would choose to plunge a knife into another human? Maybe this is just another data point in a violent heat-fueled trend. Or, as the email says about Libya, climate change “increases the likelihood” of such a thing.
But how we answer these questions – and the extent to which we dismiss climate change as a secondary concern or frivolous abstraction – defines our response.
Climate change never acts in isolation. It opens the cracks that already exist. He located the weakest point of a dam wall in a country torn by civil war; it fueled the fire in a Greek forest where a group of migrants took refuge last month; and perhaps – although we will never know for sure – it changed the course of events on a hot Saturday evening that ended in a trail of blood down a south London street.