Rising global temperatures may cause a big
jolt in the number of lightning strikes in the United States over the rest of
the 21st century in the latest example of extreme weather spawned by climate
change, scientists say.
Researchers forecast on Thursday that lightning
strikes will increase by about 50 percent by 2100 in the continental United
States because thunderstorms will become more explosive in the coming decades
thanks to a warming planet.
This increase could
lead to more wildfires because lightning already triggers half of these blazes
in the United States, the researchers said. Lightning also kills dozens of
Americans annually, with that risk expected to rise.
Considering factors
including precipitation levels, cloud buoyancy and warming air, the scientists
predicted a 7 percent increase in the number of lightning strikes with each
degree Fahrenheit global average temperature increase (12 percent for each
degree Celsius).
The 11 different
climate models used in the study pointed to an increase of 7 degrees Fahrenheit
(4 degrees Celsius) between now and 2100.
"There are about
30 million strikes per year in the contiguous U.S. now. So, in 2100, we would
expect about 45 million per year," said climate scientist David Romps of
the University of California, Berkeley and the U.S. government’s Lawrence Berkeley
National Laboratory, who led the study published in the journal Science.
"For every two
lightning strikes in 2000, there will be three lightning strikes in 2100,"
Romps added.
The researchers said
rising temperatures breed lightning because the amount of water vapor in the
atmosphere - the fuel for thunderstorms - increases exponentially as the air
gets warmer.
"As the planet
warms, there will be more of this fuel lying around, so when thunderstorms get
triggered, they will be more energetic. This increase in thunderstorm energy is
the primary reason for the projected increase in lightning strikes," Romps
said.
Many experts blame
weather intensity in recent years on global climate change they attribute to
human activities.
"The body of
research attributing trends in extreme weather to human influence is certainly
growing rapidly," said University of California, Berkeley climate
researcher Jacob Seeley.
"We are pushing
our climate system into uncharted territory, and that means we're going to see
phenomena that are extreme compared to what humans have experienced thus far
during the relatively short amount of time we have been flourishing on this
planet," Seeley added.
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