Hur­ri­canes are ex­pected to soak Texas more of­ten

Los Angeles Times - - CALIFORNIA - DEB­O­RAH NETBURN deb­o­rah.netburn @la­ Twit­ter: @Deb­o­rahNet­burn

So much for the storm of the cen­tury.

A new study sug­gests that mas­sive hur­ri­canes like Har­vey will strike Hous­ton and Texas with much greater fre­quency in the fu­ture than they do now. Why? Blame our chang­ing climate.

Ac­cord­ing to a study pub­lished Mon­day in PNAS, the odds of Har­vey-like rains drench­ing the city of Hous­ton will grow from 1 in 2,000 at the be­gin­ning of the 21st cen­tury to 1 in 100 at the end of the cen­tury.

For Texas as a whole, the out­look is even worse.

The fre­quency of hur­ri­canes with rains in ex­cess of 20 inches oc­cur­ring any­where in the state will jump from a once-in-100-years event at the end of the 20th cen­tury to a once-in-5.5years oc­cur­rence at the end of the 21st cen­tury.

The new work was led by MIT at­mo­spheric sci­en­tist Kerry Emanuel, who spe­cial­izes in hur­ri­canes.

To come to th­ese con­clu­sions, Emanuel re­lied on mod­els that are used by the Na­tional Hur­ri­cane Cen­ter to fore­cast hur­ri­canes in real time.

He also used an ar­ray of six global climate mod­els that take into ac­count a stan­dard, busi­ness-as-usual green­house gas emis­sion sce­nario.

“I wanted to be as open­minded as pos­si­ble, so I didn’t ap­ply this tech­nique to just one climate model, but rather to as many climate mod­els as I could lay my hand on,” he said.

Cur­rently about 90 hur­ri­canes a year oc­cur some­where on the globe, Emanuel said. That over­all num­ber is not ex­pected to change as the planet heats up, and in fact it might even go down.

But mod­el­ing shows that even if the to­tal num­ber of hur­ri­canes de­creases, the num­ber of re­ally in­tense hur­ri­canes — like Maria, Har­vey and Irma — will in­crease in most places.

“We are con­fi­dent about that,” Emanuel said. “And what we are re­ally con­fi­dent about is that a given hur­ri­cane will pro­duce much more rain in a warmer climate.”

He added that there are three pri­mary rea­sons why a warm­ing climate would pro­duce more se­vere hur­ri­canes in Texas in par­tic­u­lar.

For one, the data show a slight uptick in the num­ber of strong hur­ri­canes that will move into that re­gion. More im­por­tant, how­ever, is that each given hur­ri­cane will pro­duce more rain be­cause warmer air can hold more wa­ter.

Fi­nally, the mod­els sug­gest that hur­ri­canes will likely move more slowly, al­low­ing them to dump more wa­ter over a par­tic­u­lar area of land.

“We’ll see more cases of stalling, where hur­ri­canes kind of me­an­der around, which is what Har­vey did,” Emanuel said.

The tech­niques used in the pa­per are not new, but Emanuel said the sig­nif­i­cance of the pa­per is to alert city plan­ners to the chang­ing prob­a­bil­i­ties of largescale hur­ri­canes in Texas as soon as pos­si­ble.

“It is im­por­tant for those peo­ple who will re­build Hous­ton and re­think its in­fra­struc­ture to un­der­stand the mag­ni­tude of the risk and how it will change over time,” he said.

Mar­cus Yam Los An­ge­les Times

ABOUT 90 hur­ri­canes a year oc­cur some­where on the globe. Above, a res­i­den­tial neigh­bor­hood in Hous­ton in the wake of Hur­ri­cane Har­vey in Au­gust.

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