In the unscientific but compelling fable, a frog that’s dropped in a pot of boiling water will immediately hop out, but one who’s left in a pot of slowly warming water will stay there, allowing itself to be cooked. (Several myth-busting experiments have shown that a live frog will actually try to escape water as it gets warm, whereas a frog thrown in boiling water will be too hot to escape.) The allegory applies perfectly to humans’ reaction to climate change, according to a study published Feb. 25 in the Proceedings of the National Academy of Sciences.
Researchers, led by Frances Moore, professor of environmental science and policy at University of California-Davis, analyzed 2 billion tweets published between March 2014 and November 2016, to determine when people turn to Twitter to talk about the weather. Unsurprisingly, they found that there are far more weather-related tweets during unusual conditions, such as an exceptionally hot day in March or one in September that’s far colder than normal. But, they found that there was significantly less Twitter chatter when historically unusual weather conditions repeated within a few years. If a country experiences exceptionally cold weather for more than five years in a row, these conditions were no longer considered remarkable. And, overall, people’s perceptions of normal weather are based on by experiences from the past two to eight years.
This clearly raises concerns for our perceptions of climate change. Last year was the world’s fourth hottest year on record; 2017 was the most expensive year for US weather disasters in history and the third hottest year on record in the US; and in 2018 the world’s oceans reached the hottest ever temperatures in recorded history. If we adjust to these new extreme heats, and start to experience them as normal, then we’re less likely to recognize and confront the impact of climate change on the planet.
The UC Davis research shows that, while we may normalize unusual weather, we don’t get used to its impact. The authors used measured the relative numbers of positive and negative words tweeted during times of historically unusual weather. Though people tweeted less about the weather when they repeatedly experienced extreme temperatures, the researchers found that people still tweeted more negative sentiments during particularly hot or cold periods. “Temperature anomalies continue to have negative effects on sentiment even after 5–10 y[ears] of continuous exposure, long after those anomalies have become unremarkable,” they wrote in the paper.
“We saw that extreme temperatures still make people miserable, but they stop talking about it,” Moore said in a statement. “This is a true boiling-frog effect.” Climate change is only going to worsen, meaning that we’ll be exposed to more and more extreme temperatures. Maybe we just won’t notice the heat until, like the frog, we’re fully cooked.