Quantcast

Record Heat Means Hurricanes Gain Ferocity Faster

Climate
The Copernicus Sentinel-3A satellite saw the temperature at the top of Hurricane Harvey on August 25, 2017. European Space Agency / CC BY-SA 3.0 IGO

By Tim Radford

Hurricanes are becoming more violent, more rapidly, than they did 30 years ago. The cause may be entirely natural, scientists say.

But Hurricane Harvey, which in 2017 assaulted the Gulf of Mexico and dumped unprecedented quantities of rain to cause devastating floods in Texas, happened because the waters of the Gulf were warmer than at any time on record. And they were warmer because of human-driven climate change, according to a second study.


Both studies examine the intricate machinery of a natural phenomenon, the tropical cyclone. Researchers from the Pacific Northwest National Laboratory looked at how fast four of 2017's hurricanes—Harvey, Irma, Jose and Maria—intensified: episodes in which maximum wind speed rose by at least 25 knots, which is more than 46 kilometers (approximately 29 miles), per hour within a 24-hour period. They report in Geophysical Research Letters that they combed through 30 years of satellite data from 1986 to 2015 to find a pattern.

Researchers have repeatedly warned that hurricane hazard must increase with global warming, driven by profligate human combustion of fossil fuels that dump greenhouse gases in the atmosphere. Hurricanes will hit higher latitudes and deliver more damage within the Gulf of Mexico. But climate change is only part of the answer.

The latest study did not find that storms were intensifying rapidly more often than usual. But the researchers did find that when a storm grew at speed, it became much more powerful within a 24-hour period than such storms did 30 years ago: wind speeds had gained 3.8 knots or seven kilometers (approximately 4.3 miles) an hour for each of the three decades.

And although hurricanes are driven by the warmth of the upper ocean, the researchers decided that rather than overall ocean warming, in this case the biggest factor was a natural cycle called the Atlantic Multidecadal Oscillation, which in its present phase tends to make ocean waters warmer in the central and eastern Atlantic—the spawning ground for Irma, Jose and Maria.

Warmest on Record

But when Harvey hammered the Texas coast in August 2017, the waters of the Gulf of Mexico were warmer than they had ever been. And scientists from the National Center for Atmospheric Research (NCAR) report in the journal Earth's Future that they calculated the rate of evaporation as the hurricane winds raced over the water and compared it with the levels of precipitation over the city of Houston.

To make a hurricane happen at all, ocean temperatures need to reach 26°C (approximately 79°F). When Harvey gathered its strength and its moisture, the Gulf waters had tipped 30°C.

"We show, for the first time, that the volume of rain over land corresponds to the amount of water evaporated from the unusually warm ocean," said Kevin Trenberth, a senior scientist with NCAR. "As climate change continues, we can expect more supercharged storms like Harvey."

Reposted with permission from our media associate Climate News Network.

EcoWatch Daily Newsletter

A new report spotlights a U.N. estimate that at least 275 million people rely on healthy coral reefs. A sea turtle near the Heron Island in the Great Barrier Reef is seen above. THE OCEAN AGENCY / XL CATLIN SEAVIEW SURVEY

By Jessica Corbett

In a new report about how the world's coral reefs face "the combined threats of climate change, pollution, and overfishing" — endangering the future of marine biodiversity — a London-based nonprofit calls for greater global efforts to end the climate crisis and ensure the survival of these vital underwater ecosystems.

Read More
Half of the extracted resources used were sand, clay, gravel and cement, seen above, for building, along with the other minerals that produce fertilizer. Cavan Images / Cavan / Getty Images

The world is using up more and more resources and global recycling is falling. That's the grim takeaway from a new report by the Circle Economy think tank, which found that the world used up more than 110 billion tons, or 100.6 billion metric tons, of natural resources, as Agence France-Presse (AFP) reported.

Read More
Sponsored

By Gero Rueter

Heating with coal, oil and natural gas accounts for around a quarter of global greenhouse gas emissions. But that's something we can change, says Wolfgang Feist, founder of the Passive House Institute in the western German city of Darmstadt.

Read More
Researchers estimate that 142,000 people died due to drug use in 2016. Markus Spiske / Unsplash

By George Citroner

  • Recent research finds that official government figures may be underestimating drug deaths by half.
  • Researchers estimate that 142,000 people died due to drug use in 2016.
  • Drug use decreases life expectancy after age 15 by 1.4 years for men and by just under 1 year for women, on average.

Government records may be severely underreporting how many Americans die from drug use, according to a new study by researchers from the University of Pennsylvania and Georgetown University.

Read More
Water coolers in front of shut-off water fountains at Center School in Stow, MA on Sept. 4, 2019 after elevated levels of PFAS were found in the water. David L. Ryan / The Boston Globe via Getty Images

In a new nationwide assessment of drinking water systems, the Environmental Working Group found that toxic fluorinated chemicals known as PFAS are far more prevalent than previously thought.

Read More