The human body can barely cope with weather this hot. In Phoenix, where the asphalt can hit 180F, emergency-room doctors are zipping heat-stroke victims into body bags full of ice. Tens of thousands worldwide die from overheating each year, a toll that’s set to worsen. Global cities must prepare to deal with extreme heat as a matter of public health.
Several factors are converging that could make this year the hottest on record. First, heat domes have settled over large areas of North America, Europe and Asia. This happens when zones of high pressure in the atmosphere trap warm air below, pushing humidity (and cooling rainstorms) out of the system. Elsewhere, warming oceans are increasing humidity, while the recurring El Niño climate pattern is exacerbating the effects of an already warming planet.
These hotter, more humid conditions can have dire health consequences. The most serious is heat stroke, when the body loses its ability to cool down. It’s often fatal. Other issues include heat exhaustion and dehydration, which can increase the risk of heart attack or stroke. Extreme heat also exacerbates respiratory problems — even more so when the air quality is poor from pollution or wildfires. The most vulnerable include children, the elderly and outdoor workers.
City-dwellers are also at added risk. More than half the world’s population lives in cities, rising to almost 70% by 2050. Sweltering temperatures have turned some urban areas into “heat islands,” with dense concentrations of pavement, buildings and surfaces that retain heat and offer little tree cover. Peak temperatures in such cities can be 15 to 20 degrees hotter than in surrounding areas. That not only creates health risks, but reduces labor productivity, saps economic growth and stresses urban infrastructure.
Health officials and policymakers need to do more to adapt. New York City has established cooling centers and a program to subsidize air conditioning for the vulnerable, including elderly and low-income residents. Chicago created a “311” program that involved well-being checks for at-risk residents, in addition to a text-and-email emergency-notification system. Cities worldwide should create similar systems, including in Europe, where an estimated 60,000 people died from heat-related causes last summer.
Longer-term, cities should invest in infrastructure that’s better suited to a changing climate, including covered walkways, “cool roofs” with white or reflective paint, and more expansive greenery, which can make urban heat more tolerable. Equatorial cities such as Singapore have planted grass over bus stops and on the sides of buildings. Medellín, Colombia, has created a network of “green corridors,” shaded by thousands of newly planted trees. Such measures don’t always come cheap, but the cost of inaction is high. From 1992 to 2013, heat waves cost the global economy more than $5 trillion, one recent study estimated.
Even as cities adapt to warmer weather, they shouldn’t grow complacent. In addition to adopting resiliency measures, the world still needs to slash emissions, invest in clean-energy projects, impose higher costs on greenhouse gases and boost research into carbon-reducing technologies. For millions of people across the world, the heat has become impossible to ignore. It’s time policymakers come to the same conclusion.
