Statistical reports are emerging one after another that global warming may affect not only the body but also mental health. A paper published by Fudan University in China is attracting attention. This paper reports that in tropical and subtropical regions, a 1 degree rise in annual average temperature will increase violence by 4.5%. The subjects are India and other countries. From 2010 to 2018, the frequency of physical, mental, and sexual violence was examined for approximately 190,000 people in India, Nepal, Pakistan, etc. Most of these 190,000 people live in places where the annual average temperature exceeds 25 degrees Celsius. In this region, a situation has arisen in which violence against wives and other female partners increases by 5% for every 1 degree rise in the annual average temperature. It was shocking to find that if the global average temperature rises by 3.3 to 5.7 degrees at the end of the 21st century, violence in this region will increase by 21%.
To support this report, Dr. Klas Linman of Harvard University adds that heat makes people more likely to resort to short-term problem solving. When stress increases, the activity of hormone-producing tissues such as the hypothalamus, pituitary gland, and gonadal axis increases. When the activity of these hormone-producing tissues increases, people are more likely to resort to short-term problem solving, such as aggression. The fact that heat increases aggression is seen not only in humans but also in animals. Epidemiological studies have shown that animals become more aggressive when it is hot. According to a study by Harvard University in the United States, the frequency of people being bitten by dogs increases as the temperature rises. Approximately 70,000 reports of dog bites from 2009 to 2018 were analyzed in eight cities in the United States. In the analysis of these 70,000 reports, the frequency of bites was about 4% higher on days with high temperatures.
When serotonergic fibers in the forebrain of monkeys are removed, aggressive behavior increases. The lower the amount of serotonin released, the more likely criminals and men are to become antisocially impulsive. One way to suppress aggression is to improve serotonin secretion. Serotonin is also known as a resistance hormone. If you have a lot of serotonin, you will be able to behave stably during the day. Generally, increasing the amount of exercise promotes the secretion of serotonin. At night, serotonin becomes melatonin, which promotes sleep. Exercise promotes the secretion of serotonin, which results in good sleep. Then, at night, serotonin turns into melatonin, creating a virtuous cycle in which you are blessed with high-quality sleep. Maintaining this virtuous cycle may help to curb the aggressiveness caused by global warming.
