How hot could it get?

Until the end of the century, the Front Range is going to see an increasing number of 95-degree-plus days. The only question is, how many?
Christi Turner

Depending on which analysis you read, we’ve just experienced the second or third hottest October ever recorded in the U.S., preceded by the the hottest or second hottest September on record. According to NASA, August 2016 was the hottest August measured since contemporary records began, and tied July 2016 as the hottest month on record.

According to National Oceanic and Atmospheric Administration (NOAA), whose number-crunching algorithms are slightly different than NASA’s, every month from June 2016 back to May 2015 had been the hottest version of that month ever recorded. And 2016 is looking very likely to take its rightful place as the hottest year ever recorded, surpassing 2015, which had itself just eclipsed 2014 as the hottest year on record. Month by month and year by year, the heat extremes just keep getting out-extremed.

Those are global numbers, but the Front Range has been part of the trend as well. And in just a few short years, Boulder could be hotter than ever before. That’s what a recent report from the Rocky Mountain Climate Organization (RMCO), a Louisville-based organization that works to reduce climate disruption in the U.S. West, is predicting. In this latest report, RMCO analyzed the latest available data from global climate models, which was then downscaled to a local level and triangulated with local weather data from long-standing weather stations in Boulder. The RMCO team then crunched that data to predict the total number of days that could reach 95 degrees or higher across 20-year time periods from now through 2099.

The predictions are based on four different possible scenarios of greenhouse gas concentrations, from very low to high, and they vary accordingly; in other words, the study shows how many 95-degree-plus days we’ll have if we do a poor job of curbing greenhouse gas emissions, versus if we do a really good job of it.

“This is the most detailed local projected analysis that has been done anywhere, at least in the United States,” says Stephen Saunders, RMCO president. “We took projections from all available models for all these different emission scenarios, and when you add them all together we had 44 million individual projections of weather.”

Already, the report says, the average number of days with temperatures of 95 degrees and higher in Boulder County so far this century (11 days) is more than twice the average number of the previous century (five days). Looking ahead to the period of 2020 to 2039, it predicts Boulder could experience as few as 16 and as many as 21 days — three whole weeks -— of 95 degrees or hotter days. By 2040 to 2059, the region could see between 20 and 38 days of this heat, and by the 2060 to 2079 period, between 17 and 58 days. Finally, by 2080 to 2099, the report predicts, Boulder could see as few as 18 but as many as 75 days per year — the equivalent of two-and-a-half months — with temperatures of 95 degrees or hotter. Viewed another way, between now and 2099, if the world does a very good job curbing greenhouse gas emissions, Boulder could see 95-degree-plus days increase from the 2000 to 2016 average of 11 days to just 18. If it does a poor job, the increase could be from 11 days to 75 — nearly seven times as many extremely hot days.

Nolan Doesken, State Climatologist for Colorado, says the RMCO’s temperature projections for Boulder are consistent with other current climate forecasts. Doesken is more cautious about precipitation projections included in the RMCO report, which he says are far more difficult to predict, even if there is confidence about temperature.

“But the warming temperature we can kind of hang our hats on,” he says. “There’s a very solid basis for that.”

Despite the predictions, Doesken is hopeful that technological advances will transform the global economy into a less carbon-intensive one. But there’s no certainty. “We can predict human economic activities much less than we can weather-related stuff,” he says.

For Saunders, the value of looking at the four distinct emissions scenarios in the RMCO report is that it highlights just how great a difference each scenario can make to future temperature predictions.

“If we bring down emissions sharply, we’ll continue to have extreme heat in the next 20 year period, but it won’t get much worse after that,” Saunders says. “We’d get more, a bit more, but it doesn’t keep getting worse. It’s tolerable. It could still be a good place for us to live and work and play.”

Previous articleBroomfield votes to adopt five-month moratorium on oil and gas operations
Next articleWhat is the ‘Trump Fix’