We’re not expected to get beyond the mid-80s today in the part of California where I live, but last week was a different story, when a bout of extreme heat brought a glimpse of unity, giving me hope for our chances to usher in energy solutions.  

Early in the week, the temperature climbed to 115 degrees, dropping just a few degrees over the next couple of days. That’s sweltering, even by local standards, where the summer highs rarely exceed 105. 

As if to underscore the alarming heat, our cellphones screeched in unison on the hottest day in 73 years. The record highs had created record demand on the state’s power grid. A plea from the state flashed across our screens. It read, in part: “Conserve energy now to protect public health and safety. … Power interruptions may occur unless you take action.”

It was impossible to ignore. I walked around the house turning off lights. It was dusk, so my family talked and worked in the ambient glow of lingering daylight for as long as possible, then used lights sparingly after dark. Laundry and dishes were put on hold while large appliances got the night off. 

Turns out, millions of Californians did the same thing. Demand on the state’s power grid dropped immediately, and rolling blackouts were avoided.

The next morning’s headlines lauded the collective action, as did Elliot Mainzer, president and chief executive of the California Independent System Operator, which manages the state’s power grid. “I do know it had a significant impact,” said Mr. Mainzer at a media briefing, “and demonstrates the capacity of Californians to respond and flex their demand when they really appreciate the severity of the issue.”

We know that’s not enough. The state’s need for more energy production has been widely reported – and how best to do that, widely debated. But for an evening, millions of us were on the same page. Unity proved possible.