Geoengineering takes a ride in shipping lanes

Pacific Northwest National Laboratory: Ships blowing off steam are helping researchers understand how manmade particles might be useful against global warming. New results from modeling clouds like those seen in shipping lanes reveal the complex interplay between aerosols, the prevailing weather and even the time of day the aerosol particles hit the air, according to research presented today at the American Association for the Advancement of Science's annual meeting.

"We've seen ship tracks affect the reflectivity of clouds," said Phil Rasch, chief climate scientist at the Department of Energy's Pacific Northwest National Laboratory in Richland, Wash. "We want to know if we can do the same thing when we want to, on purpose, and how that might be helpful in countering some of the effects of global warming. "We decided to see how the reflectivity of clouds is influenced by particles in a very detailed model that treats clouds much more realistically than we are able to do in a typical climate model."

Reflecting sunlight back into space prevents that energy from hitting Earth's surface. So brighter clouds could have an overall cooling effect compared to darker ones. A handful of research groups in the US are exploring geoengineering, or the intentional modification of Earth's climate, in hopes of developing tools that might be used to lower global temperatures if atmospheric greenhouse gases reach levels that might produce disastrous climate change.

…"Do the brighter and darker parts cancel each other out?" asked Rasch. To find out, the group performed some exploratory computer simulations to determine the net effect of increased aerosols. His team simulated three ships chugging along in a 93-mile by 37-mile block of the Pacific Ocean a few hundred miles southwest of Los Angeles.

The team showed that introducing additional particles into the model near the surface — as proposed for geoengineering — would make the clouds significantly more reflective than they would otherwise be, in certain situations. They found that if the clouds were already drizzling then the new particles would not brighten them very effectively….

A tanker (Abqaiq) takes on oil from Iraq's Mini-Al Basrah offshore terminal. Shot by an employee of the US government