Nevada is heating up.
In 2017, the state reached its highest summer temperature since recordkeeping began, according to data from the National Oceanic and Atmospheric Administration. The finding tracks with the planet’s accelerated warming trend, a result of fossil fuel emissions and other human activities.
“It’s the same type of pattern we are seeing everywhere,” said Daniel McEvoy, who studies weather patterns at the Desert Research Institute’s Western Regional Climate Center in Reno.
Weather vs. climate
Although the trend line suggests an average temperature increase of about 0.2 degrees per decade, there is considerable variation in year-to-year summer temperatures. Why? That’s the weather.
- Weather describes the short-term behavior of the atmosphere. It is driven by decadal and even shorter cycles. These include the El Niño and La Niña oscillations, which are driven by changes in oceanic temperature. Such cycles account for the natural spikes and drops.
- Climate is more predictable because it describes the long-term trend. Where weather is discussed in hours and days, climate is viewed in 30-year increments or centuries. It shows the long-term behavior of the atmosphere, a region’s average weather pattern.
So, will every summer be warmer?
“I’d be surprised if we had any decade in the future that is cooler than the previous,” said Matt Lachniet, a UNLV geologist and climate scientist, who first reported the NOAA data on his blog. “But we are going to have big year-to-year differences. If you look at the data already, you see year-to-year differences that are much larger than the decadal trends. That’s because of weather.”
The population centers
In all but one city, the 2017 summer was the hottest in the instrumental record. Carson City, Ely, Las Vegas and Reno all recorded their warmest average temperatures from June to August. The only city that departed from the overall trend was Elko, which listed a record warm summer in 2013, when it’s average temperature was 71.7 degrees (this summer was close at 71.6 degrees).
The trend was most extreme in Las Vegas, where average summer temperatures are increasing at a rate of nearly one degree (0.8 degrees Fahrenheit) per decade. To give a snapshot of what this looks like: In 1949, the average summer temperature for the Las Vegas region was 85.9 degrees.
This year it was 93.2 degrees.
The NOAA data shows that minimum summer temperatures are generally rising faster than maximum summer temperatures. This means that nights are getting warmer faster than days, McEvoy said, a trend that is playing out not just in Nevada but also throughout the United States.
“It’s not cooling down as much,” he said.
The result is a trickle-down effect, said Nick Obradovich, a researcher at the MIT Media Lab who has studied the effect of climate change on sleep. In a study published earlier this year, he and other researchers found a connection between higher nighttime temperatures and disruptions in sleep.
“One of the things that is kind of important to consider is the degree to which the average is being pushed up by extremes,” Obradovich said. “With respect to things like sleep, it seems to be more anomalous temperature increases that affected sleep quality.”
People aren’t losing a week of sleep. But “the downstream effects of (it) are also important to consider,” Obradovich said, noting that sleep can affect mood and productivity. “People tend to be less happy, a little grumpier.”
Over time, average temperatures are expected to keep going up, and weather is expected to become more extreme, increasing the intensity of heat waves, precipitation and droughts.
“Climate models are predicting more extremes in the future,” McEvoy said.
According to the government’s National Climate Assessment, unless global emissions are reduced, temperatures in the Southwest are expected to rise as much as 5.5 degrees by 2070, perhaps even earlier. This could reduce water supplies and hurt the economy, especially in tourism and agriculture, according to the report, which was compiled in 2014 by leading researchers at institutions including UNLV, NOAA and the National Park Service.
“The trends clearly show that we can expect summers to get hot each year going forward,” said Elspeth DiMarzio, a Nevada representative for Sierra Club’s nationwide campaign to close coal plants. “That’s why I feel it is so urgent we stop contributing to climate change in the state.”