Heat waves fuel hate, while cooler heads prevail at 60 degrees

POTSDAM, Germany — Climate change may be the cause of rising tensions and hate speech online, according to new research. Study authors from the Potsdam Institute for Climate Impact Research say incidents soar by more than a fifth when the temperature rises.

Global warming is getting people hot under the collar during conversations on social media in particular. Temperatures above 86°F show a consistent link to this phenomenon. The study authors say this applies to all climate zones irrespective of socioeconomic differences such as income, religious beliefs, or political preferences.

The findings, published in The Lancet Planetary Health, have implications for social cohesion, suggesting there will be more aggression and violence unless greenhouse gas emissions fall dramatically. Scientists used a computer neural network to analyze four billion tweets from users in the United States.

Why does heat lead to hate?

“People tend to show a more aggressive online behavior when it’s either too cold or too hot outside,” says study first author and PIK scientist Annika Stechemesser in a media release.

“Being the target of online hate speech is a serious threat to people’s mental health. The psychological literature tells us that online hate can aggravate mental health conditions especially for young people and marginalized groups,” Stechemesser adds. “We see that outside the feel-good window of 12-21°C (54-70°F) online hate increases up to 12 percent for colder temperatures and up to 22 percent for hotter temperatures across the USA.”

The artificial intelligence algorithm identified around 75 million English phrased hate tweets in the data set from 2014 to 2020. Researchers then analyzed how the number changed when local temperatures increased or decreased.

Using official U.N. guidelines, the team defined hate speech as discriminatory language with reference to a person or group on the basis of their religion, ethnicity, nationality, race, color, descent, gender, or other identity factors.

“Detecting hate tweets in more than four billion tweets from U.S. users with our AI-algorithm and combining them with weather data, we found that both the absolute number and the share of hate tweets rise outside a climate comfort zone,” Stechemesser continues.

What temperature keeps tempers cool?

Lower levels of hate speech appeared online in the “feel-good window” of 54 to 70°F — with fewest occurring when it was between 59 and 65°F outside. The results point to “limits of temperature adaptation capability,” according to the team.

“Even in high-income areas where people can afford air condition and other heat mitigation options, we observe an increase in hate speech on extremely hot days. In other words: There is a limit to what people can take. Thus, there are likely limits of adaptation to extreme temperatures and these are lower than those set by our mere physiological limits,” says Anders Levermann, head of Complexity Science at the Potsdam Institute and a researcher at Columbia University.

The consequences can be severe, even leading to more hate crimes in the real world.

“For centuries, researchers have grappled with the question of how climate conditions affect human behavior and societal stability,” explains study leader Leonie Wenz.

“Now, with ongoing climate change, it is more important than ever. Our results highlight online hate speech as a new impact channel through which climate change can affect overall societal cohesion and people’s mental health. So that means that curbing emissions very rapidly and drastically will not only benefit the outer world. Protecting our climate from excessive global warming is also critical to our mental health.”

South West News Service writer Mark Waghorn contributed to this report.

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