Atlanta’s heat raises red flags

As the heat soared past 100 degrees last weekend, a new temperature record in Atlanta — 106 — grabbed headlines. What is most remarkable about this event is not only the extremity of the temperature, but also the accelerating frequency with which Atlanta is experiencing unusually hot weather.

In recent years, the number of summer days with temperatures above 90 has exceeded the long-term average by more than 30 days. Atlanta’s summers are not simply growing hotter over time; Atlanta ranks among the top three most rapidly warming cities in the nation — and quite possibly in the world.

Atlanta’s rapid warming is due not only to the global greenhouse effect, which is inarguably driving warming trends in cities worldwide, but also to the extremity of a local-scale phenomenon known as the “urban heat island effect.” As cities displace forests and farmland with darkly hued roads, buildings and parking lots, more sunlight is absorbed and retained throughout the day, further elevating urban temperatures.

Having cut down more acres of trees to fuel sprawling growth than perhaps any other city in the country, Atlanta’s heat island has grown unusually intense, contributing to an accelerating rate of warming that is double that of the planet as a whole.

The growing incidence of extreme heat in cities like Atlanta is a deadly serious problem. Across the country, the annual number of heat-wave days in large cities has doubled since the 1950s.

With this greater incidence of extreme heat comes the growing risk of heat-related deaths during heat waves. Today in the U.S., more Americans die from extreme heat each year than from all other forms of severe weather combined.

The death toll from recent extreme heat events is staggering, with more than 50,000 heat fatalities in Russia in 2010, and more than 70,000 lives lost during a 2003 heat wave across Europe.

We need only look to Washington, D.C., and surrounding areas this week to understand our growing vulnerability to extreme heat: An estimated 3 million residents confronted 100-degree temperatures during a massive blackout. That means no power to run air-conditioning systems, transportation systems and, in some instances, deliver drinking water.

The unpleasant truth is that Atlanta may be only one extreme heat wave away from a Katrina-like episode. And we are utterly unprepared.

There are effective steps we can take to reduce our growing vulnerability to extreme heat. First, strengthen emergency response plans to provide relief to the most vulnerable residents and ensure the continuing operation of critical infrastructure during heat waves. Second, combat heat island formation through massive tree planting and a resurfacing of rooftops and streets with more highly reflective materials. The restoration of our rapidly diminishing tree canopy is the single most effective option available to moderate the intensity of heat waves and slow our rapid pace of warming.

Brian Stone is a professor of city and regional planning at Georgia Tech and author of “The City and the Coming Climate: Climate Change in the Places We Live.”