Climate change made Hurricane Harvey's rainfall worse, study finds

Climate change is partly to blame for the record rainfall that fell over Texas and Louisiana in the days after Hurric...

Posted: Dec 13, 2017 8:18 PM
Updated: Dec 13, 2017 8:18 PM

Climate change is partly to blame for the record rainfall that fell over Texas and Louisiana in the days after Hurricane Harvey's landfall on August 25, according to new scientific analysis.

Human-caused climate change made the rainfall from Harvey, which dumped more than 19 trillion gallons of water and brought devastating floods to the Houston area, roughly three times more likely to occur and 15% more intense, according to World Weather Attribution (WWA), an international coalition of scientists led by nonprofit scientific research group Climate Central, in a report published Wednesday.

The question of whether climate change played a role in the disaster came up almost immediately, as it so frequently does after extreme weather events.

It was assumed that climate change contributed to Harvey's rainfall, as intense rainfall events are one of the most often cited consequences of a warming climate. The observational data and computer models used in this study supported that assumption.

As air temperature warms, it can hold more moisture (about 7% more per degree Celsius of warming), which means there is more water vapor in the air that can be squeezed out as rainfall in a world warmed by climate change.

Other factors, such as changes in upper level winds and sea level rise can also contribute to increased flood events.

The WWA study examined extreme precipitation events in the US Gulf Coast region since 1880 and found "a clear positive trend between 12% and 22%." Using computer models loaded with this data and comparing it to similar models that do not show the climate warming, the authors attempted to quantify the role that the warming climate had on the 2017 event.

Harvey, which rapidly intensified to a Category 4 storm just before landfall near Corpus Christi, Texas, stalled after it moved inland and remained nearly stationary for four days. This allowed rainfall totals to add up in and around Houston, reaching levels never before seen in a landfalling tropical system.

Cedar Bayou, about 30 miles east of Houston, recorded 51.89 inches of rainfall by the morning of August 31. That eclipsed the 48-inch rainfall record from Tropical Storm Amelia in 1978 and set a new record for the continental US.

The biblical flooding across Harris and surrounding counties required more than 120,000 people to be rescued or evacuated, and about 80 people died.

Though the economic impact from Harvey is still being calculated, "it is likely a $100 billion disaster," according to Adam Smith, lead researcher at the National Oceanic and Atmospheric Administration's National Centers for Environmental Information.

"Harvey is the closest modern disaster comparison we have in relation to Katrina in terms of damage costs," Smith told CNN.

The WWA study looked only at the role climate change played in the amount of rainfall Harvey produced, ignoring other variables that made Harvey so exceptional, such as the rapid intensification before landfall and the unusual lack of movement it had in the following days.

"It's clear that Harvey's exceptional rainfall was due to the stalling and looping nature of the track of the storm -- which this study does not address in the slightest," Ryan Maue, a meteorologist with weather.us who was not affiliated with the study, told CNN.

But that doesn't mean Maue is refuting its conclusion.

"There's little doubt that global warming has and will continue to enhance rain rates and intensity, but it's not clear that this paper has teased out all of the possible mechanisms that led to Harvey's extreme flooding impacts," Maue said.

Minnesota Coronavirus Cases

Data is updated nightly.

Confirmed Cases: 26980

Reported Deaths: 1159
CountyConfirmedDeaths
Hennepin9099657
Ramsey3351149
Stearns205614
Nobles15775
Anoka152779
Dakota144664
Washington70035
Olmsted68911
Rice5243
Kandiyohi5141
Scott4712
Clay44930
Mower4462
Wright3492
Todd3441
Sherburne2492
Carver2402
Benton1853
Steele1700
Freeborn1590
Blue Earth1490
Martin1355
St. Louis11914
Lyon1012
Unassigned9611
Pine930
Nicollet8811
Cottonwood820
Winona8115
Crow Wing815
Watonwan790
Carlton750
Goodhue736
Otter Tail731
Chisago691
Polk632
Itasca5610
Dodge540
Chippewa521
Morrison480
Le Sueur471
Douglas460
Meeker460
Becker440
Jackson420
Murray410
McLeod410
Isanti360
Pennington300
Waseca290
Mille Lacs241
Rock230
Faribault220
Wabasha200
Swift191
Beltrami180
Sibley170
Brown172
Fillmore171
Norman150
Pipestone130
Kanabec121
Aitkin120
Marshall120
Cass112
Big Stone110
Wilkin113
Wadena100
Pope100
Koochiching90
Redwood70
Yellow Medicine70
Renville70
Mahnomen61
Lincoln60
Red Lake40
Traverse40
Grant40
Clearwater30
Houston30
Hubbard30
Lac qui Parle30
Roseau30
Stevens10
Lake10
Kittson10

Iowa Coronavirus Cases

Data is updated nightly.

Confirmed Cases: 21114

Reported Deaths: 593
CountyConfirmedDeaths
Polk4614140
Woodbury286137
Black Hawk178849
Buena Vista10672
Linn97879
Dallas95226
Marshall91418
Wapello63615
Johnson6198
Muscatine56741
Crawford5512
Tama41129
Scott38510
Dubuque35921
Louisa35011
Pottawattamie31910
Sioux3060
Jasper26917
Wright2210
Washington1968
Warren1671
Plymouth1522
Story1311
Allamakee1204
Mahaska9913
Poweshiek928
Hamilton760
Webster741
Henry732
Boone720
Bremer716
Clarke690
Des Moines681
Taylor660
Clinton651
Guthrie553
Cedar501
Benton431
Cherokee410
Monroe415
Jones370
Shelby370
Osceola360
Jefferson360
Marion350
Dickinson350
Buchanan341
Iowa340
Clayton343
Cerro Gordo331
Madison292
Lee290
Sac280
Davis280
Emmet270
Fayette270
Clay270
Monona260
Harrison260
Hardin240
Lyon240
Winneshiek240
Lucas222
Mills200
Grundy200
Franklin200
Humboldt201
Pocahontas200
Delaware191
Floyd191
Hancock180
Appanoose173
Butler161
Kossuth160
Carroll151
Ida150
Greene150
Keokuk140
Jackson140
Page140
Audubon131
Cass130
Chickasaw130
Howard120
Winnebago110
Calhoun100
Union100
Van Buren90
Adair90
Montgomery92
Adams70
Palo Alto70
Ringgold40
Fremont40
Mitchell40
Worth30
Unassigned20
Wayne10
Decatur10
Rochester
Few Clouds
72° wxIcon
Hi: 79° Lo: 61°
Feels Like: 72°
Mason City
Clear
80° wxIcon
Hi: 82° Lo: 64°
Feels Like: 80°
Albert Lea
Broken Clouds
75° wxIcon
Hi: 81° Lo: 64°
Feels Like: 75°
Austin
Overcast
75° wxIcon
Hi: 81° Lo: 64°
Feels Like: 75°
Charles City
Overcast
79° wxIcon
Hi: 82° Lo: 62°
Feels Like: 79°
Weekend looks nice
KIMT Radar
KIMT Eye in the sky

Latest Video

Image

Sean Weather 6/6

Image

Chris' PM Weather Forecast 6/5

Image

Gyms, fitness centers set to reopen

Image

Easing restrictions for MN restaurants and gyms

Image

Charles City vigil for George Floyd

Image

Hawkeye Harvest Foodbank partnership

Image

Next phase of Minnesota reopening

Image

Rental Assistance program for Rochester

Image

IA Care Homes Could Reopen to Visitors

Image

'Color Me Mine' Location Closes for Good

Community Events