Humans made recent storms wetter
498 views · Published 19 November 2018 · 6:58 · Indexed 13 October 2026
Channel: AP Archive · 2018 · News & Politics
(14 Nov 2018) LEAD IN : Two new studies show how in different ways humans made recent hurricanes Harvey, Maria, Irma and Katrina even wetter. Scientists say Harvey actually got caught by the Houston downtown causing it to rain more - a new phenomenon. For the other storms, climate change made the storms 6 to 9 percent rainier. STORYLINE : Humans have helped make recent devastating hurricanes wetter, and not just through climate change, according to two new studies. One study looked at 2017's major Hurricanes Maria and Irma and 2005's deadly Katrina, and used computer simulations to see what would have happened if there had been no human-caused global warming. The study found that climate change significantly increased those three storms' rainfall, but did not boost their wind speed. The researchers looked at 15 historical damaging storms from across the globe and tried to calculate past and future effects of climate change. For three storms, Maria, Irma and Katrina, the authors looked at what would happen with no climate change effect, finding 8.9 percent, 6.3 percent and 8.7 percent increases in rainfall, but not wind strength. In Maria's case "there's actually a structural change in the storms in this model as the climate gets warmer," according to co-author Michael Wehner, a climate scientist at the Lawrence Berkeley National Laboratory. For all 15 storms, which included the devastating Haiyan, the potent Gilbert and 1992's Hurricane Andrew, the scientists projected future warming, with future versions of the same storms becoming significantly wetter and stronger. The second study published in the Nature says that Hurricane Harvey snagged on the built-up skyscrapers of Houston, causing it to slow and rain more than it normally would. Between being tripped up by downtown and the bigger effect of massive paving and building up of the metro area to reduce drainage, development in Houston on average increased the extreme flooding risk by 21 times. In the case of Harvey last year, scientists used computer simulations to see the effects of urbanization on the storm's record rainfall that reached five feet in one place. In parts of the Houston metro area, the effects of development, building on surfaces that normally would drain water and being slowed down by the city itself , ranged from a 10 percent higher risk in the less developed northwest to nearly 92 times the risk in the northeast area of the region. What outside experts found groundbreaking about the study is the effect of the city itself on the storm. Paving and building on green areas didn't allow water to sink into the ground. The importance of grassland in drainage can be demonstrated by pouring water on a lawn and watching it sink in compared to pouring it on a driveway and watching it puddle. And these effects are on top of the unique weather patterns that made Harvey slow down and stall over Houston, and climate change which brought more water into the storm to fall as rain. Both studies are published in the journal Nature November 14, 2018. Find out more about AP Archive: http://www.aparchive.com/HowWeWork Twitter: https://twitter.com/AP_Archive Facebook: https://www.facebook.com/APArchives Instagram: https://www.instagram.com/APNews/ You can license this story through AP Archive: http://www.aparchive.com/metadata/youtube/4895442844bd979adf8e68bf9b0cdda3
