When does summer end? It’s a tricky question, and while there is an astronomical answer (for the northern hemisphere, it’s the autumnal equinox on September 22), I’m not sure that most people think that way. Ten months ago, FiveThirtyEight published a fun, informal article about this very thing. We shouldn’t take this too seriously, but there was a roughly three-way-tie amongst respondents on what was the end of summer and the start of autumn. Of the responses, 26% stuck to the autumnal equinox. Another 25% pinned the end of summer on when the color of leaves start to change. Yet another 25% say that summer ends with Labor Day, which was September 5 this year. But I’m guessing that if you had asked Californians on Tuesday, September 6 if autumn had begun, you’d have been met with some combination of “no,” “heck no,” and death stares.
A Crisis Averted in California
Sacramento set a record high temperature of 116 degrees that day. Cities in the Bay Area also hit record highs, including San Jose at 109 degrees and Napa at 114 (I wonder what that will do to the wine crop this year?). Death Valley, California was only 125 degrees that day, which is nothing compared to the 127 degrees it was on September 2! That was the hottest September day ever recorded in Death Valley, FYI.
So yes, California hasn’t had the best weather recently. It’s more than just unpleasant, however. There were serious concerns about electricity providers needing to institute rolling blackouts across the state over concerns of grid stability. That’s what I want to unpack with this blog, but I’ll go ahead and tell you the end of the story - they averted catastrophe. As demand for electricity was threatening to exceed its supply on the afternoon of September 6, a FlexAlert text went out to the people of California, urging them to conserve electricity. It appears that enough people listened and most blackouts were avoided. If you want to really dig into the data of what happened that day, here’s the California ISO webpage with historic demand and supply. If you look at the “Demand Trend” graphic and set the day to September 6, you can see how electricity demand noticeably declined between 5:50 and 6:10pm local time. I guess demand response is an effective climate solution, huh?
Electric Vehicles Weren’t The Problem, and One Day They Might Be a Solution to Heat Waves
I want to do three things with the remainder of this blog. For your appetizer, I will be swatting away an annoying line-of-reasoning that I saw pop up during the heat wave. As a main course, I will be reminding you all of the public health concerns associated with heat waves. And for your dessert, we will have a nuanced exploration of how heat waves don’t just present a demand-side concern for electricity grids; they also present challenges on the supply side. Let’s dig in.
In various places, including newspaper opinion pieces and twitter threads, I saw quite a few “hot” takes (sorry, I couldn’t help myself). I won’t link to any because I don’t want to drive traffic to them, but for a flavor, just search for “California heat wave electric vehicles” on Twitter. They all went something like this: “Silly California - you’re running out of electricity AND trying to get people to switch to electric vehicles.” To this, I have two responses, and the first is to point out the obvious. Heat waves are made more likely and more severe by increased concentrations of greenhouse gases in the atmosphere, which has been caused in part by…wait for it…gas powered cars. It would be like telling a smoker not to quit because doing so would be hard. Secondly, I encourage you all to read this article from Axios that explains how electric vehicles can help to stabilize the grid, rather than threaten it.
Heat and Its Impacts on Human Health
On to the main course. Several years back, I wrote an Ecocentricity blog about how heat waves are the extreme weather event that kills the most Americans each year. That appears to still be the case. According to the National Weather Service, heat waves continue to outpace floods, tornadoes, cold, and riptides in terms of fatalities. Further, as global warming accelerates, I expect heat waves will continue to claim a disproportionately higher share of weather-related fatalities. The biggest challenge will be higher nighttime low temperatures, which will make it harder for people to shed the heat from the day. This New York Times article from last year does a good job of breaking that down, and it emphasizes how nights are warming faster than days and why warmer nights are deadlier.
It’s not just about deaths, however. Heat-related illness is its own problem. According to the CDC, symptoms of heat exhaustion, when the body is struggling to shed heat, include headache, fatigue, nausea, cramping, and dizziness. When heat exhaustion proceeds to heat stroke, the brain and other organs can be damaged. Guess who is most at risk for heat exhaustion and heat stroke? Surprise surprise - it’s children, elderly people, and those with certain comorbidities. And what happens when you put a socioeconomic lens on top of that data analysis? It shows that low-income and minority populations are disproportionately at-risk. When you see information like this, it makes it clear that the climate crisis isn’t just an environmental issue - it’s an acutely social issue as well.
Heat Impacts Electricity Supply Too, Not Just Demand
Lastly, I noticed that a lot of the recent heat wave coverage focused on the surge in demand that came from it. Basically, folks were correctly noting that the hotter temperatures meant people were running their air conditioners more, resulting in more consumption of electricity. Demand surges were seen as the culprit. I think it’s really important, however, to understand the supply side challenges too. As heat waves become more and more common, communities will be challenged both by these demand surges AND the declining efficiency of electricity generation in hot conditions. Basically, the gadgets we humans make to fill our grid with electrons don’t work as well when it’s blazing hot outside.
The reason is different for the various forms of generation, and this report from the Oak Ridge National Laboratory does a good job of explaining why (check out pages 9 and 10). For thermoelectric generation (think coal, nuclear, and natural gas), hotter temperatures mean warmer water used for coolant and less dense air, both of which constrain the efficiency of the power plants. For photovoltaics, as the solar cells get too hot, they begin to be less efficient. Warmer temperatures can even decrease the efficiency with which power lines transmit electricity.
The bottom line is pretty simple. Heat waves are a problem, and they are only getting worse.