Ways to keep cities cooler dur­ing heat waves

The Charlotte Observer (Sunday) - - Obituaries - BY BRAD PLUMER

Cities can be mis­er­able dur­ing heat waves. All that con­crete and as­phalt soaks up the sun’s rays, push­ing tem­per­a­tures even higher. Tall build­ings can block cool­ing breezes. Ex­haust from cars and air con­di­tion­ers just adds to the swel­ter.

This is known as the ur­ban heat is­land ef­fect: A large city’s built-up en­vi­ron­ment can make it 2-5 de­grees Fahren­heit warmer than the sur­round­ing coun­try­side dur­ing the day and up to 22 de­grees warmer at night. That ex­tra heat is be­com­ing a se­ri­ous pub­lic health prob­lem. On av­er­age, 650 Amer­i­cans die each year from heat-re­lated causes, the Cen­ters for Dis­ease Con­trol and Preven­tion es­ti­mates, and global warm­ing is only ex­pected to make things worse.

Dur­ing re­cent years, some ur­ban plan­ners have been seek­ing cre­ative strate­gies to com­bat the heat is­land ef­fect to pro­vide relief and pre­vent more peo­ple from dy­ing dur­ing bru­tal hot spells. “Cities need to re­al­ize that they have the power to change their own weather,” said Brian Stone, Jr., a pro­fes­sor at Ge­or­gia Tech’s School of City and Re­gional Plan­ning.

Here is a look at a few of the more promis­ing ideas that cities around the world have been pur­su­ing to try to beat the heat. Bring back the trees: This sum­mer in Dal­las, where a per­sis­tent heat dome has sent tem­per­a­tures soar­ing past 105 de­grees, vol­un­teers have fanned out around the low-in­come neigh­bor­hood of Oak Cliff, work­ing with res­i­dents to plant 1,000 trees around schools and homes.

Trees do not just pro­vide much-needed shade for a sweaty city. The wa­ter evap­o­rat­ing from their leaves can cool a neigh­bor­hood by a few de­grees dur­ing the hottest pe­ri­ods. Tree leaves also ab­sorb and fil­ter lo­cal air pol­lu­tion – a cru­cial ben­e­fit, since heat waves can worsen ur­ban smog, send­ing peo­ple to the hospi­tal with asthma and other ill­nesses.

Seat­tle now en­cour­ages de­vel­op­ers to add rooftop gar­dens or even walls cov­ered by veg­e­ta­tion to new build­ing projects. Lon­don re­cently con­ducted an au­dit of its cen­tral busi­ness dis­tricts and iden­ti­fied over 10 mil­lion square feet of space that could be con­verted to rain gar­dens, green roofs and green walls.

Let the wind blow: In the in­dus­trial city of Stuttgart, Ger­many, re­fresh­ing breezes are scarce and valu­able. The city sits in a river val­ley basin, sur­rounded by steep hills that can trap both heat and pol­luted air over the re­gion. It is a po­ten­tially lethal com­bi­na­tion dur­ing the hot­ter months.

In re­sponse, Stuttgart has cre­ated a num­ber of ven­ti­la­tion cor­ri­dors through­out the city: wide, tree-flanked ar­te­rial roads that help clean air flow down from the hills at night to cool the city. Of­fi­cials also have re- stricted new build­ings from go­ing up on cer­tain hill­sides to keep the air mov­ing.

Some ex­perts are skep­ti­cal this strat­egy will work for ev­ery city be­cause a lot de­pends on lo­cal weather pat­terns and ge­og­ra­phy. But China is be­com­ing in­ter­ested.

Paint roofs white: One big rea­son cities are so much hot­ter than ru­ral ar­eas is they are cov­ered by dark roofs, roads and park­ing lots that ab­sorb and re­tain heat. Dur­ing re­cent years, many ur­ban plan­ners have sought to re­place those dark sur­faces with lighter, more re­flec­tive ma­te­ri­als.

Through its CoolRoofs Ini­tia­tive, New York City has painted more than 5 mil­lion square feet of its roofs with a re­flec­tive coat­ing. Los An­ge­les is re­plac­ing some of its dark as­phalt roads with brighter ma­te­ri­als.

Get peo­ple to cool­ing cen­ters: When dan­ger­ous heat waves ar­rive, ac­cess to air con­di­tion­ing can be a mat­ter of life or death. That is why more cities are set­ting up pub­lic cool­ing cen­ters to of­fer relief for those who might lack cool air at home.

But pub­lic health ex­perts say set­ting up cool­ing cen­ters is only half the bat­tle: The other half is get­ting peo­ple to them. One re­cent sur­vey of Detroit, Philadel­phia, Phoenix and New York found that pub­lic cool­ing cen­ters were of­ten poorly pub­li­cized or dif­fi­cult to ac­cess by pub­lic trans­porta­tion.

“There’s this large so­cial and be­hav­ioral com­po­nent to heat waves that doesn’t get nearly enough at­ten­tion,” said Jalonne L. White-New­some, a se­nior pro­gram of­fi­cer at the Kresge Foun­da­tion who led the study.

In Philadel­phia, many neigh­bor­hoods des­ig­nated block cap­tains who will check on older res­i­dents dur­ing a heat wave.

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