Climate change boosted Helene's deadly rain and wind and scientists say
same is likely for Milton
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[October 09, 2024]
By ALEXA ST. JOHN
Human-caused climate change boosted a devastating Hurricane Helene 's
rainfall by about 10% and intensified its winds by about 11%, scientists
said in a new flash study released just as a strengthening Hurricane
Milton threatens the Florida coast less than two weeks later.
The warming climate boosted Helene's wind speeds by about 13 miles per
hour (20.92 kilometers per hour), and made the high sea temperatures
that fueled the storm 200 to 500 times more likely, World Weather
Attribution calculated Wednesday from Europe. Ocean temperatures in the
Gulf of Mexico were about 3.6 degrees Fahrenheit (2 degrees Celsius)
above average, WWA said.
“Hurricane Helene and the storms that were happening in the region
anyway have all been amplified by the fact that the air is warmer and
can hold more moisture, which meant that the rainfall totals — which,
even without climate change, would have been incredibly high given the
circumstances — were even higher,” Ben Clarke, a study co-author and a
climate researcher at Imperial College London, said in an interview.
Milton will likely be similarly juiced, the authors said.
The scientists warned that continued burning of fossil fuels will lead
to more hurricanes like Helene, with “unimaginable” floods well inland,
not just on coasts. Many of those who died in Helene fell victim to
massive inland flooding, rather than high winds.
Helene made landfall in Florida with record storm surge 15 feet (4.57
meters) high and catastrophic sustained winds reaching 140 miles per
hour (225.31 kilometers per hour), pummeling Georgia, the Carolinas,
Tennessee and Virginia. It decimated remote towns throughout the
Appalachians, left millions without power, cellular service and supplies
and killed over 230 people. Search crews in the days following continued
to look for bodies. Helene was the deadliest hurricane to hit the
mainland U.S. since Katrina in 2005.
Helene dumped more than 40 trillion gallons of rain — an unprecedented
amount of water — onto the region, meteorologists estimated. That
rainfall would have been much less intense if humans hadn’t warmed the
climate, according to WWA, an international scientist collaborative that
runs rapid climate attribution studies.
“When you start talking about the volumes involved, when you add even
just a few percent on top of that, it makes it even much more
destructive,” Clarke said.
Hurricanes as intense as Helene were once expected every 130 years on
average, but today are about 2.5 times more likely in the region, the
scientists calculated.
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Teresa Elder walks through a flooded Sandy Cove Drive from Hurricane
Helene, Sept. 27, 2024, in Morganton, N.C. (AP Photo/Kathy Kmonicek,
File)
The WWA launched in 2015 to assess the extent which extreme weather
events could be attributed to climate change. The organization’s
rapid studies aren’t peer-reviewed but use peer-reviewed methods.
The team of scientists tested the influence of climate change on
Helene by analyzing weather data and climate models including the
Imperial College Storm Model, the Climate Shift Index for oceans and
the standard WWA approach, which compares an actual event with what
might have been expected in a world that hasn't warmed about 1.3
degrees Celsius since pre-industrial times.
A separate analysis of Helene last week by Department of Energy
Lawrence Berkeley National Lab scientists determined that climate
change caused 50% more rainfall in some parts of Georgia and the
Carolinas, and that observed rainfall was “made up to 20 times more
likely in these areas because of global warming.” That study was
also not peer-reviewed but used a method published in a study about
Hurricane Harvey.
Kim Cobb, director of the Institute at Brown for Environment and
Society, wasn't involved in either study. She said there are
uncertainties in exactly how much climate change is supercharging
storms like Helene, but “we know that it’s increasing the power and
devastation of these storms.”
She said Helene and Milton should serve “as a wake up call” for
emergency preparedness, resilience planning and the increased use of
fossil fuels.
“Going forward, additional warming that we know will occur over the
next 10 or 20 years will even worsen the statistics of hurricanes,"
she said, "and we will break new records.”
Analysis is already indicating climate change made possible the
warmed sea temperatures that also rapidly intensified Milton. Clarke
said the two massive storms in quick succession illustrates the
potential future of climate change if humans don't stop it.
“As we go into the future and our results show this as well, we
still have control over what trajectory this goes in as to what
risks we face in the future, what costs we pay in the future," he
said. "That just hinges on how we change our energy systems and how
many more fossil fuels we burn.”
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