Warming climate may fuel more lightning

Rising global temperatures may cause a big jolt in the number of lightning strikes in the US over the rest of the 21st century in the latest example of extreme weather spawned by climate change, scientists say.

Researchers forecast yesterday that lightning strikes will increase by about 50 per cent by 2100 in the continental US 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 US, 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 US 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 US 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 said.

The researchers said rising temperatures breed lightning because the amount of water vapour 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,” Romps said.

“This increase in thunderstorm energy is the primary reason for the projected increase in the number of lightning strikes.”

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," Seeley said.
– (Reuters)