A viral tweet from anti-LGBTQ activist James Lindsay about wet-bulb temperatures is consistent with years of efforts from right-wing influencers to interfere with attempts to educate the public about the dangers of climate change and extreme heat. 

Lindsay, like other conservative media figures, has seized the opportunity in recent years to drag various global environmental initiatives into the broader culture wars. For him, climate change denial and delay are tools for defeating so-called “cultural marxism.”

On July 17, as multiple countries suffered dangerous and ongoing heat waves, Lindsay loudly downplayed the severity of conditions so humid they interfere with humans’ ability to sweat and push the limits of survivability, promoting an allegedly purposeful misinterpretation of “wet-bulb” temperature to his followers. 

Terms like “heat index” and “wet-bulb temperature,” both of which describe ways to measure the stress that heat puts on the body, seem to be appearing more frequently in media coverage and public discourse as increasingly hot and humid summers disrupt daily life and pose significant threats to public health. 

As media consumers seek to understand coverage of the extreme heat, climate change skeptics have attempted to mislead their audiences about these terms, typically by downplaying their seriousness.

What is wet-bulb temperature?

According to the National Weather Service, a wet-bulb thermometer “measures the temperature read by a thermometer covered in a wet cloth. As water evaporates from the cloth, evaporation cools the thermometer. This mirrors how the human body cools itself with sweat.” 

Wet-bulb temperature changes depending on how humid it is, but will always be lower than the more familiar “dry-bulb” temperature. It was developed in the 1950s to help prevent heat-related illness and casualties in the U.S. armed forces and is typically used to assess the safety of outdoor activities in hot weather. 

If the wet-bulb temperature reaches a certain point and the air is already saturated with enough water, the body can lose its ability to cool itself by sweating, potentially leading to heat stroke and other adverse health effects, or even death. It was initially thought that a healthy human would not be able to survive for more than six hours at a wet-bulb temperature of 95 F, but according to a more recent study conducted by Penn State researchers, the critical wet-bulb temperature is actually closer to 87 F, even for healthy young people.  

Attempts to disrupt the conversation around extreme heat aren’t new

Lindsay’s comment received immediate backlash for being blatantly incorrect, but a chorus of Twitter users also echoed his sentiment, with some even suggesting that wet-bulb measures are a hoax fabricated by the government to frighten people. 

It’s unclear whether wet-bulb temperatures in the US actually reached 94 degrees, as the tweet suggests, but according to the Washington Post, “wet-bulb temperatures hovered in the upper 80s to around 90 degrees” throughout the southern U.S. on July 17, creating extremely risky conditions for developing heat-related illness. On July 16 in Iran, the wet-bulb temperature reached 92.7 degrees Fahrenheit.

Lindsay tried to walk back his statement after the backlash, claiming that the purpose of the tweet was to demonstrate “engagement hacking” because it was “misleading (sort of), cheap, and easy. New Twitter incentivizes the hell out of this kind of thing.”

But regardless of intent, this isn’t the first time a right-wing influencer has attempted to muddy the waters around terms related to extreme heat. During a 2011 heat wave, for example, Rush Limbaugh suggested on his show that heat index was a government conspiracy. Right-wing media have made a regular practice of pushing climate change denial during heat waves. 

Heat index is similar to wet-bulb, and measures how hot it actually feels with relative humidity taken into account, though it’s only meant to be used in shaded areas. 

Limbaugh’s and Lindsay’s comments represent clear attempts to get media consumers to dismiss coverage of rising temperatures and extreme heat waves as Americans are beginning to better understand the gravity of their effects. If you don’t know how bad a problem is, you’re unlikely to support solutions. 

Heat is considered to be a silent killer and is responsible for more deaths than all other weather disasters combined. Driven by climate change, the already dangerous conditions playing out around the world this July are only expected to get worse. In addition to hindering climate action, dissuading people from taking basic safety precautions to cope with the heat will put lives at risk. But if we learned anything from COVID, it’s that right-wing media aren’t above doing that.