What's with this heat?

“I know darn well that it’s hotter here than it was when we were kids.”

The comment came from one of a group of mostly Renoites at a party in Verdi last month. After that comment, there was a murmur of agreement from those surrounding the speaker, most of whom grew up in Reno in the 1950s and 1960s. The occasional days of three-digit temperatures Reno has been seeing in recent weeks likely reinforces that opinion.

But such comments in more diverse groups will often result in disagreement, sometimes from those who deny climate change is happening.

While there are fluctuations from year to year, there is indeed data that shows Reno has been getting steadily hotter since about the Second World War, though whether that fact says anything about the region’s climate is far from certain.

In the late 1940s and 1950s, there were only two years (1950 and 1958) when Reno’s average annual temperature was above 50 degrees.

But since 1980, there were only two years (1982 and 1985) when Reno’s average annual temperature was below 50 degrees.

On a flow chart, there are fluctuations, but also a steady upward rise over seven decades. So the data is there to show Reno is generally hotter now than it was. But data is always subject to interpretation. Is Reno hotter because the climate has changed at this point near the Sierra—or because Reno has become a larger urban area, what some people call an urban heat bubble? Such islands are caused by buildings preventing surface heat from dissipating into the night sky and a lack of evaporation and transpiration through plants, among other factors.

Western Regional Climate Center research climatologist Nina Oakley said, “There is also the urbanization, the effect of urbanization, an urban heat island in Reno. … How do you separate what’s happening in the atmosphere from what’s the effect of urban heat islands?”

In fact, she said, there are studies nearing completion to try to sort out which factor is having more impact on Reno, but that information won’t be available for a while. One of the frustrations of dealing with scientists is that they seldom provide unqualified, conclusive answers. Most of them will only go as far as the data takes them, and there is a surprising amount of information on Reno-area weather that is not in easily readable form or has not been analyzed to address some issues.

Whether the rise in Reno temperatures is something that is happening throughout the Great Basin is also still to be determined. There is data from numerous weather stations, but it has not been gathered together for this kind of use, and some stations do not lend themselves to such use. A station at Beowawe has been in place only since 1972, so comparing it to the much longer emplaced Reno station is less than fruitful. One Battle Mountain station stopped operating in 1945. As far as we have been able to tell, there is no table or list showing a statewide annual average temperature.

Non-scientists react to different kinds of information. Some may cherry-pick information to support what they want to believe. Others have an inclination to project a small amount of experience onto a broader field, their personal impressions—such as a couple of brutal summers in a row—leading them to sweeping conclusions.

Justin Broglio of the Desert Research Institute said, “We get the same question in the winter time during the snowfall. When there’s no snowfall at all, people call with the same kind of question. You know, ’We’ve had two years of no snowfall.’” And they want to know whether that shows a trend.

Some climate experts challenge the whole notion of heat islands. National Climatic Data Center scientist Thomas Peterson wrote in one study, “Additionally, as a [scientific] community, we need to update our understanding of urban heat islands, to realize that this phenomenon is more complex than widely believed by those not immersed in the field. We should not view all oddly warmer stations as indications of UHI. Some urban stations are indeed warmer than nearby rural stations but almost the same number are colder.”

It’s just one of the issues still to be settled about Reno’s climate. To those suffering from the heat, it may not matter what the cause is.

According to the Centers for Disease Control, “The state with the highest average annual hyperthermia-related death rate during 1999—2003 was Arizona (1.7 deaths per 100,000 population), followed by Nevada (0.8) and Missouri (0.6).” Clark County is likely responsible for most of that ranking.