Space

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// B Y S A R A H D E R O U I N //

Tidal Floods

Are Coming to

More U.S. Cities,

Thanks to the

Moon’s Wobble

T

IDAL FLOODS CAN SHUT DOWN HIGH-

ways, turn parking lots into lakes, and

spread runoff from overwhelmed sewage

systems. And while they’ve been more

common to low-lying East Coast cities

like Miami or Charleston, South Carolina,

coastal towns that have historically stayed

dr y could soon find themselves under water, accord-

ing to a study published in Nature Climate Change.

Until five years ago, tidal f loods in Hawaii, for

example, were a rarity, says Phil Thompson, Ph.D.,

the study’s lead author and a physical oceanogra-

pher at the University of Hawaii. If sea levels rise in

line with NOA A’s Intermediate Sea Level Rise sce-

nario (roughly three feet globally by the end of the

centur y), Thompson and his fellow researchers pre-

dict a dramatic increase in tidal f looding events in

some cities in the coming decades.

The planet has warmed more than one degree

Fahrenheit over the past century. This warming

has spurred polar ice sheets to melt and has driven

the expansion of seawater, adding about 1/8 of an

inch of water to the world’s oceans annually. By

the end of this decade, sea level is projected to have

risen 3.5 to 7 inches compared with the year 2000.

While rising sea levels play the lead role in

28 November/December 2021

ILLUSTRATION BY COLIN MCSHERRY USING GETTY IMAGES (MOON, SEA, TEXTURES) AND CAROLINE DELBERT (RED LINE)