Summer Heat Waves and Global Warming Are Here to Stay

You better get used to hot, sticky summers like this one, says climatologist Heidi Cullen, who explains terrifying data of why the weather is only getting hotter and how our infrastructure can’t handle it.

Is it fall yet?

As the latest heat wave passed through the East Coast, some were wondering if this summer’s heat would ever end. If you ask just about anyone in the northeast what this past July was like, they’ll tell you it was hell. On July 6, Central Park hit 103°F which led to reports of electrical transformers bursting into flames and underground cables going haywire. In Washington, D.C. they had 20 days with temperatures above 90°F and Philadelphia had two days above 100°F. There’s no doubt that the heat was awful for everyone, but as a climatologist who studies global warming, I found these high temperatures a troubling peek into where our weather is headed and how poorly prepared we are to deal with it.

Heat is the No. 1 weather-related killer in the United States—ahead of tornadoes, floods, or lightning strikes.

Let’s look at how July 2010 might stack up against the Julys of the future. Using climate models and a well-established statistical method for calculating shifts in average and extreme temperature, we can actually generate an informed projection of how July 2010 might compare with those in the years ahead—assuming we continue to pump heat-trapping gases into our atmosphere at a rate similar to today (what scientists refer to as the A1B scenario). In other words, we can estimate when July 2010—which ran about 4°F to 5°F hotter than average this year in the northeast—might become the average July.

Turns out, it’s pretty soon. According to the calculations, within 40 years the brutal heat that gripped cities like Boston, New York, Philadelphia, and Washington, D.C. could be more or less normal:

So if this July will be considered average or cooler than average by 2050, what kind of extreme temperatures can we expect to see by then? By projecting the number of days hotter than 90°F, 95°F and 100°F out to the middle of the century, it looks like we could see 10 percent to 50 percent more days that reach these torrid milestones:

With the high temperatures of this past July leading to brownouts throughout the northeast, it should come as no surprise that our aging power grid is currently ill-equipped to deal with demands like those that are likely to be placed on it by 2050—when the Census Bureau projects the United States will have roughly 130 million more people. Historically, for each 1.8°F of warming, cooling demand increases between 5 percent and 20 percent due to more people turning on air conditioners, refrigerators and then air conditioners having to work harder, higher resistance losses in transmission wires, and other factors. The end result of increasing heat and population growth is greater demand for electricity. The U.S. Energy Information Administration estimates electricity demand by 2050 could be 50 percent higher than it is today.

High demand and high temperatures are a dangerous combination—in some cases even deadly. Heat is the No. 1 weather-related killer in the United States—ahead of tornadoes, floods, or lightning strikes. The infamous Chicago heat wave in 1995 resulted in over 700 heat-related deaths over a period of five days. Projections for Chicago suggest this could become the average number of deaths due to heat waves by the 2050s.

As the debate over whether or not to curb heat-trapping gas emissions drags on, it doesn’t take away the serious risks posed by increased heat. If we can’t pass legislation to address the cause of global warming, we will most certainly have to deal with its consequences. That means preparing today for the warmer world of tomorrow. That means adding new transmission lines and making the grid smarter so that it can better handle demand spikes in hot weather and better utilize intermittent low-carbon electricity sources like wind and solar.

More than just saving lives, these investments will pay good returns. And while climate change may seem like low a priority during a recession, a recent study of federally declared disasters by the Multihazard Mitigation Council found that for every $1 spent on risk reduction measures and infrastructure improvements, roughly $4 was saved in the long run.

Change is often difficult, but when you plan ahead you can actually come out ahead.

Heidi Cullen is a senior research scientist with Climate Central, a nonprofit research organization through which she reports on climate change for news outlets, including PBS NewsHour,, and The Weather Channel. She is a visiting lecturer at Princeton University, a member of the American Meteorological Society, and an associate editor of the journal Weather, Climate, and Society.