Last week, Schuster and a team of researchers in Singapore published a study shedding new light on the air microbiome — the puzzling and complicated combination of microorganisms in the air. If this is your first time hearing the term “air microbiome,” you’re not alone. Most researchers don’t even know it exists, Schuster said. But there is an entire ecosystem in the air, just like there are terrestrial and aquatic ecosystems teeming with life across the planet.

“People make the assumption that there’s nothing in the air because we can’t see it,” he said. But there is another world up there swirling with bacteria, fungi, and other microorganisms that have been blown off the surface of the planet and suspended in the air. Schuster’s study is the first in the world to examine how climate change may be affecting the way this invisible ecosystem moves. His paper cracks open the door to an entirely new chapter of research into the field of air microbiology and its implications for human and planetary health in a warming world.

The problems Schuster ran into with his research echoed the crux of the analysis of that COVID-infected diner in Guangzhou. Schuster wasn’t accounting for ventilation and airflow. He didn’t realize that the air he was measuring at the bottom of the mountain was flowing up along the ridge to the top of the peak, so the air he sampled at the top of the mountain was the same air he had tested just minutes earlier below. And he also wasn’t accounting for a phenomenon called “atmospheric mixing,” when warm temperatures and turbulence mix up all the microorganisms in the air like a giant centrifuge. Peak mixing occurs during the day, when temperatures are warmer, and settles down at night, when it gets cooler.

Warmer temperatures change the formula of fungi and bacteria in the atmosphere. More warming equals more fungi, many of which are pathogens, rising up through the earth’s boundary layer — the lowest part of the troposphere. “With climate change, the fungi are now being transported to a higher and higher level” within the troposphere, Schuster explained. The higher fungi rise off the ground, the more easily they can spread out and colonize new terrain. “At the moment you are at a high level, you can distribute much much wider,” he said. In the tropical regions of the world, the air microbiome has a lot more fungal pathogens, plant pathogens, and bacteria swirling around than the air in colder regions.

The takeaway is alarming: As the planet warms, Schuster’s research suggests that those tropical air microbiomes could move north and south. Eventually, they might even reach the Earth’s poles, Schuster said. “This will mean that plant and animal pathogens will become invasive in regions where they are currently not seen,” he added. That could have implications for humans and the crops we grow for food.

Read the full article about air microbiome by Zoya Teirstein at Grist.