Study: Hotter Climate Leads to...More Violence

New Jersey U.S. Senate candidate Rush Holt made the bold claim last week that "millions will die" and "there’s pretty good evidence that millions already have died" as a result of global climate change. Though the Democratic congressman didn't specify how he thinks climate change is killing people, one can assume he meant extreme environmental changes. For example, the wildfire that killed 19 firefighters in Arizona was attributed to global warming by some.

But could people themselves be implicated in such "climate-change related" deaths as well? A new study associating a hotter climate with violence might suggest so.

Researchers at Princeton University and the University of California-Berkeley are saying a hotter, wetter climate might increase violent actions among humanity.

The research published in the journal Science this week about "Quantifying the Influence of Climate on Human Conflict" analyzed 60 quantitative studies and found a "strong causal evidence linking climatic events to human conflict across a range of spatial and temporal scales and across all major regions of the world."

Graphs showing the relationship between various climate factors and conflict. (Images: AAAS/Science via Princeton.edu)

More specifically, the research stated that violence between people increased 4 percent and 14 percent between groups of people.

"Because locations throughout the inhabited world are expected to warm 2 to 4σ by 2050, amplified rates of human conflict could represent a large and critical impact of anthropogenic climate change," the study stated.

The researchers are clear to state that climate is not the only factor causing an uptick in violence, but Princeton's article on the study states that researchers believe it "undeniably exacerbates existing social and interpersonal tension in all societies, regardless of wealth or stability."

"Whether there is a relationship between climate and conflict is not the question anymore. We now want to understand what's causing it," the study's lead author Solomon Hsiang said in a statement. "Once we understand what causes this correlation we can think about designing effective policies or institutions to manage or interrupt the link between climate and conflict."

"We find the same pattern over and over again, regardless of whether we look at data from Brazil, Somalia, China or the United States," Edward Miguel, a professor of environmental and resource economics at Berkeley, added. "We often think of modern society as largely independent of the environment, due to technological advances, but our findings challenge that notion. The climate appears to be a critical factor sustaining peace and wellbeing across human societies."

Why would a hotter climate increase violent interactions among people? Some theories include the negative influence it might have on the economy, specifically agriculture, or heat leading to increased irritability and aggression in general on a personal level. The researchers found individual people were more violent in hotter temperatures.

"There's a large amount of evidence that environmental conditions actually change a person's perception of their own condition, or they also can change the likelihood of people using violence or aggressive action to accomplish some goal," Hsiang said.

A separate paper published in Science on Thursday stated temperatures in much of North America and Eurasia are likely to go up by that 5.4 degrees by about 2065 because of increases in carbon dioxide pollution.

The same paper sees global averages increasing by about 3.6 degrees in the next half-century. So that implies essentially about 40 percent to 50 percent more chance for African wars than it would be without global warming, Miguel said.

When the Intergovernmental Panel on Climate Change updates its report next year on the impacts of global warming, it will address the issue of impacts on war for the first time, said Carnegie Institution scientist Chris Field, who heads that worldwide study group. The new study is likely to play a big role, he said.

The Associated Press contributed to this report. Featured image via Shutterstock.com.

(H/T: BBC)

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