Carrot Weather, the customizable weather app known for its whimsical forecasts, rolled out a new update this week that includes reports on whether or not your temperatures in your area are, well, survivable. The app will now show so-called wet bulb readings, a key climate metric.
Wet bulb temperature is a metric that combines measurements of temperature, humidity, heat radiation, and wind in a complicated equation to determine what conditions our bodies can withstand. It’s designed to mimic a measurement taken by a thermometer covered by a water-soaked cloth.
In the Carrot app, the wet bulb temperature reading is still accompanied by the app’s quirky comments. But the risks are serious. Take the 80-degree-Fahrenheit (26.7-degree-Celsius) conditions show in the screenshot at the top of this post, for instance. Scientists have found that at that wet bulb temperature, working in the sun for more than half an hour or so can put the human body under serious stress.
Research shows that the human body reaches its limit at a wet bulb temperature of 95 degrees Fahrenheit (35 degrees Celsius); spending more than six hours in these conditions would be fatal, even for people in perfect health. As the planet heats up due to the continued release of greenhouse gas emissions by fossil fuel companies and other industries, in some places, these conditions are not just something to theoretically muse about, but rather something to be wary of in day to day life. This summer, Jacobabad, Pakistan—a city of 200,000 people—surpassed the deadly wet bulb threshold.
Brian Mueller, the developer of Carrot Weather, was inspired to add a wet bulb reading to the app after reading a recent viral Twitter thread on the phenomenon.
“It does a good job of explaining why the wet-bulb temperature is important, especially with all the climate change-induced heat waves going around,” he said.
Mueller prides himself on having the “most customizable weather app out there,” complete with different layouts, choices for whether forecasts should include profanity, and widgets for different gadgets.
“So it made sense to add wet bulb temps as a data point that you could slot into any section in the main iOS app, the Apple Watch app, or the Home Screen widget,” he said.
Climate change is increasing the risk that parts of the tropics could become uninhabitable because of the rising heat and wet bulb temperatures. With heat waves roaring across the West this summer and the rising heat and humidity in the South, it’s a reminder deadly extremes are coming for parts of the U.S., too. By giving app users the wet bulb temperature, Carrot can provide a real warning about how safe it is to be outside for prolonged periods and also clue users into how the climate crisis is already altering the weather in dangerous and possibly deadly ways.
“It’s terrible what is happening to the planet, but hopefully Carrot can make a difference by helping people better track what exactly is happening,” he said.