We know this in Malta. As the summer lazily crawls into August, and it gets hotter and drier, so do our tempers. We argue more, sporadic fights break out and the driving… well, the least said the better.

Yesterday was Santa Marija – our own Ferie. Everything slows to a halt as people just try and relax. We avoid the heat, the sun and anything that might make us irritable – simply because it’s too hot and no one can be bothered.

It seems that we Maltese are right. As the world gets warmer, people are more likely to get hot under the collar, scientists say. A massive new study finds that aggressive acts like committing violent crimes and waging war become more likely with each added degree.

Researchers analyzed 60 studies on historic empire collapses, recent wars, violent crime rates in the United States and lab simulations that tested police decisions on when to shoot. They found a common thread over centuries: Extreme weather — very hot or dry — means more violence.

The authors say the results show strong evidence that climate can promote conflict.

The team of economists even came up with a formula that predicts how much the risk of different types of violence should increase with extreme weather. In war-torn parts of equatorial Africa, it says, every added degree or so increases the chance of conflict between groups— rebellion, war, civil unrest — by 11 % to 14 %. Temperatures in much of North America and Eurasia are likely to go up significantly by about 2065 because of increases in carbon dioxide pollution.

The same paper sees global averages increasing by about 2 C in the next half-century.  Analyzed studies looked at temperature and conflict, and the link was clear, no matter where or when.

In one study, police officers in a psychology experiment were more likely to choose to shoot someone in a lab simulation when the room temperature was hotter. In another study, sportsmen pitchers were more likely to retaliate against their opponents when a teammate was hurt on hotter days. The study also pointed to the collapse of the Mayan civilization that coincided with periods of historic drought about 1,200 years ago.

There is a good reason why people get more aggressive in warmer weather. Although people say they feel sluggish when they are hot, their heart rate and other physical responses are aroused and elevated. They think they are not agitated, when in fact they are, and that's a recipe for disaster. Well, it’s funny to think that it took a whole team of scientists to prove what the Maltese have always known. Added heat just makes us all hotter under the collar.