The scent of pine trees can influence a process that affects sunlight and cloud cover.
The pine-scented vapors emitted by coniferous trees form particles "seemingly out of nowhere," a University of Washington news release reported.
"In many forested regions, you can go and observe particles apparently form from thin air. They're not emitted from anything, they just appear," Joel Thornton, a University of Washington associate professor of atmospheric sciences and second author on the paper, said in the news release.
New research suggests these particles may be the primary source of aerosols over boreal forests.
The particles in question can grow from one nanometer in size to 100 nanometers in only a day; the 100 nanometer particles can reflect sunlight and are also large enough to absorb water vapor and influence cloud formation.
The researchers took measurements in the Finnish pine forests and then simulated the same particle formation in an air chamber. The team observed that when the pine-scented molecules react with the surrounding ozone free-radicals "grab oxygen with unprecedented speed," the news release reported.
"The radical is so desperate to become a regular molecule again that it reacts with itself. The new oxygen breaks off a hydrogen from a neighboring carbon to keep for itself, and then more oxygen comes in to where the hydrogen was broken off," Thornton said.
Chemists would predict only three to five oxygen molecules would be added per day through oxidation, the team witnessed 10 to 12 oxygen molecules being added in one step. These molecules grab ahold of smaller molecules in hopes of transitioning from a gas to a solid or liquid. When a number of these molecules clump together they grow large enough to influence climate.
"I think unravelling that chemistry is going to have some profound impacts on how we describe atmospheric chemistry generally," Thornton said.
As temperatures rise the trees tend to give off more of these scented molecules. Understanding how these particles affect the climate could help researchers better-predict how the world will respond to global warming.
"It's thought that as the Earth warms there will be more of these vapors emitted, and some fraction of them will be converted to particles which can potentially shade the Earth's surface," Thornton said. "How effective that is at temperature regulation is still very much an open question."
