Psychological effects of global warming

The psychological effects of global warming are less well debated than the impact on the planet, but are also of concern.

Some experts have drawn a direct correlation between rising temperatures and an increase in aggressive and violent behavior, including violent crime.

But is there evidence of a direct link between hot temperature and aggressive behavior?

• Social psychologists have shown in laboratory experiments that simply being in a hot room makes people feel angrier than being in a comfortable room. Aggressive thoughts also increase.
• Other laboratory research has shown that hot temperatures can, when coupled with provocation, increase a person’s willingness to hurt another person.
• Other research shows that regional differences in violent crime rates are related to regional differences in ambient temperature and hotter regions of a country tend to have higher violent crime rates.
• In the 1990's the Journal of Personality and Social Psychology reported on two studies that examined the relation between hotness of year and violent crime rate in the United States from 1950 to 1995. One study found that summer produced more violent crime—murders and assaults—than the other seasons. If high temperature was a direct cause of the summer effect, then years with more hot days (days in which the maximum temperature is at least 90F) would have somewhat larger increases in murder and assault than years with fewer hot days. This prediction was confirmed by the data.
• The second study examined the relation between the average temperature for each year and the corresponding murder and assault rate for the same 46-year period. If hot temperatures have a direct effect on violent behavior, then hotter years should (on average) produce higher violent crime rates. This is exactly what happened. The combined murder-and-assault rate was consistently higher in hotter years than in cooler ones. These results occurred even when the data were statistically controlled for the poverty rate, age shifts in the U.S. population and the general upward drift of violent crime during the period.

This information on the psychological effects of global warming is based on findings from Craig Anderson, PhD, a professor of psychology at the University of Missouri at Columbia.