Texans have a complicated relationship with the heat. We complain about it all the time, but we also take a certain satisfaction in our suffering. Of course, the increasingly scorching summers are getting more and more difficult for even the hardiest soul to bear, and there’s no end in sight. John Nielsen-Gammon, the state climatologist, is one of the leading experts on why Texas has gotten hotter and how much hotter it still might get.
Texas Monthly: How have temperatures in Texas changed over the past fifty years?
John Nielsen-Gammon: Well, 1970 to 1979 was the coldest decade on record for Texas, and 2011 to 2020 was the hottest decade on record for Texas. Starting with the eighties, every decade in Texas has been warmer than the decade before—1997 was the last year in which the Texas temperature was below the twentieth-century average. Every year since then has been warmer.
TM: What role does climate change play in all this? Are we expecting this trend to continue?
Nielsen-Gammon: The trend over the past fifty years in Texas is very close to what climate model simulations have predicted because of global climate change. The projection for the next fifty years is a similar continuation of the trend.
In general, we expect temperatures in Texas to increase a little faster than the global average, mainly because continental areas warm up faster than the ocean. Oceans take longer to catch up.
TM: Does the Gulf of Mexico help moderate our temperatures?
Nielsen-Gammon: It does. The projected increase in temperature along the Texas coast is a bit smaller than the projected increase inland. But all the oceans are warming too, so the land will come along for the ride.
TM: A lot of Texans pride themselves on tolerating the heat. But at what point will the state start experiencing dangerous heat for long stretches of the year? Are we already there?
Nielsen-Gammon: What’s dangerous is relative. It’s dangerous if you’re not expecting it. The weather that was such a big deal for the Pacific Northwest [in the summer of 2021] wouldn’t be such a big deal for Texas. But we have seen the number of hundred-degree days double between the seventies and today. It’s projected to double again over the next half century.
That’s going to be a lot of days over one hundred degrees. There will be more days over one hundred and ten. Summer is going to last longer. People will need to take more precautions against the heat, because the heat’s going to be more powerful.
TM: What about humidity? How does that change things?
Nielsen-Gammon: In Texas we get our humidity from the Gulf of Mexico. In the past, when we had unusually high temperatures, we had low humidity. But as high temperatures become more common, humidity will increase too.
TM: How might a hotter Texas affect agriculture?
Nielsen-Gammon: The growing season is going to start earlier because frost and freezes will end earlier. But at the other end of the growing season, temperatures will get hotter, faster. For crops that aren’t heat tolerant, the growing season will get compressed. It will be a bigger challenge.
TM: Will the increased heat contribute to other types of severe weather?
Nielsen-Gammon: The most direct effect of increased heat is increased intensity of rainfall. A hotter atmosphere holds more water vapor, and it takes more water vapor to start producing rain. Consequently, the rainfall ends up being more intense when it does happen.
We’ll also see an increase in the risk of the strongest hurricanes. There’s an increase projected in the type of weather that produces tornadoes and severe thunderstorms, but that’s about as far as we can go with that.
TM: What about drought, though? Don’t heat and drought go hand in hand?
Nielsen-Gammon: Higher temperatures don’t help drought conditions. They make things get worse faster.
The rainy days are wetter, the drier days are more common, and there are bigger gaps between rain. And if the temperature goes up, things dry up faster when you do have a lack of rainfall. So that would make droughts more frequent and more intense.
TM: What should we expect fifty years from now?
Nielsen-Gammon: Temperatures will presumably be averaging another two to three degrees Fahrenheit warmer. But most importantly, we’ll know by then whether temperatures will keep going up or whether we’ve managed to stabilize greenhouse-gas concentrations. That’ll be the most interesting thing in fifty years.
This interview has been edited for clarity and length.
This article originally appeared in the February 2023 issue of Texas Monthly with the headline “Actually, It Is the Heat.” Subscribe today.
