Shipping Exhaust Intensifies Thunderstorms, Study Suggests

A new study says lightning strokes occur nearly twice as often above heavily-trafficked shipping lanes. File Image / Pixabay

The American Geophysical Union (AGU) and the University of Washington, in a new study mapping lightning around the world, suggests that lightning strokes occur nearly twice as often directly above the heavily-trafficked shipping lanes in the Indian Ocean and the South China Sea compared to areas of the ocean adjacent to shipping lanes that have similar climates.

The study's authors explain that the difference in lightning activity cannot be explained by changes in the weather, concluding that aerosol particles emitted in ship exhaust are changing how storm clouds form over the ocean.

The results are said to provide some of the first evidence that humans are changing cloud formation on an almost continual basis as opposed to specific incidents, like individuals wildfires.

"It's one of the clearest examples of how humans are actually changing the intensity of storm processes on Earth through the emission of particulates from combustion," said Joel Thornton, an atmospheric scientist at the University of Washington and lead author of the study.

The new study, which is said to be the first to show ship exhaust can alter thunderstorm intensity, saw researchers conclude that particles from ship exhaust make cloud droplets smaller, lifting them higher in the atmosphere, creating more ice particles that leads to more lightning in the process.

"We're emitting a lot of stuff into the atmosphere, including a lot of air pollution, particulate matter, and we don't know what it's doing to clouds," said Steven Sherwood, an atmospheric scientist at the University of New South Wales who was not connected to the study.

"That's been a huge uncertainty for a long time. This study doesn't resolve that, but it gives us a foot in the door to be able to test our understanding in a way that will move us a step closer to resolving some of those bigger questions about what some of the general impacts are of our emissions on clouds."