Consider this nightmare state of affairs. For 4 days now, temperatures have soared previous 110 levels. Those in a position to keep house are cranking their air-conditioning whereas officers scramble to maneuver the unhoused into cooling facilities. Even at night time, the sweltering is relentless, due to the urban heat island effect: The concrete and brick of this metropolis absorbs the solar’s power in the course of the day and releases it all through the night.

There isn’t any aid, after which all of the sudden there’s catastrophe: The grid fails, snatching away the AC that’s staving off mass warmth sickness. If this state of affairs had been to unfold throughout Phoenix, in keeping with a latest paper, half of the town’s 1.6 million individuals would want medical consideration. More than 13,000 would die.

With local weather change, then, gained’t residing in a spot like Phoenix get ever extra precarious? After all, the warmer it will get, the extra individuals have to run their AC, including ever extra stress to the grid. Well, there is a motive the United States hasn’t seen such an excessive mass-mortality occasion: For all its faults, the electrical grid is surprisingly resilient to warmth emergencies.

And but, warmth is already a hidden disaster. Statistically, it causes extra deaths every year than another weather-related occasion—an estimated 12,000 per year within the US—nevertheless it doesn’t get the headlines that hurricanes, floods, or tornadoes do. And past that mortality fee, excessive warmth exacerbates underlying well being issues, sends individuals to hospitals, stresses emergency medical transport, and hikes well being care spending.

The danger of warmth sickness and demise, like many well being issues, falls hardest on those that can do the least to guard themselves. Lower-income neighborhoods are quantifiably hotter than richer areas, as a result of they have an inclination to have fewer bushes that cool the panorama. And in fact, lower-income households are much less prone to have air-conditioning within the first place, which means their residents are already extra vulnerable even earlier than the facility goes out.

When an city warmth wave rages for a number of days, and temperatures don’t come down a lot at night time, the physique will get no time to get well. “These buildings are very dense: concrete materials push the heat into the residences and expose those folks to levels that it’s not going to be easy to comfortably sleep,” says Portland State University local weather adaptation scientist Vivek Shandas, who research the city warmth island impact. “It’s not going to be easy for the body to really go into that deep rest state.”

The excellent news is that {the electrical} grid is best in a position to face up to a warmth wave than you may assume. A hurricane or earthquake causes widespread destruction of the grid infrastructure, downing energy traces or damaging energy crops. Heat, in contrast, may overload some transformers, or power an influence plant to scale back its power era to maintain from overheating. But the grid as an entire stays intact.

“Those issues are real, and they do occur, but it’s not widespread,” says Jeff Dagle, chief electrical engineer on the Pacific Northwest National Laboratory, who research the grid. “It’s not like every time we have a heat wave, we have massive numbers of transformers that fail. It’s a relatively small impact on the overall system that’s designed with redundancy and resilience.”