Teeming communities of microorganisms fill the air over our heads, and scientists are just beginning to learn what their presence means for weather, climate change and human health.
A story by Vanessa Schipani inThe Scientist reports every cubic meter of air holds more than 100 million tiny organisms.The airborne particles of dust that travel over and above land masses also carry vast and diverse assortments of bacteria, fungi and viruses. It turns out that the earth’s atmosphere has microbial diversity that is on a par with the microbial life of terrestrial soil.
Jessica Green, a microbial ecologist at the University of Oregon, thinks microbes are inhabitants of the air, not just riders on the wind.If microbes are metabolically alive-eating, breathing, reproducing-while suspended in air and cloud water, she says, they could potentially sustain population through many generations.”If the atmosphere is a habitat where microbes live,” she says, "this will fundamentally change our conception of atmospheric processes.”
Christine Rogers, an aerobiologist at the University of Massachusetts, explains how airborne microbes may influence climatechange. She says increased carbon dioxide in the atmosphere may be creating more and larger plants, which provide food for microscopic fungi. Microbes provide surfaces for condensation of water vapor, so they have an important role in forming clouds and influencing rain and snow. Scientists say if the microbes are metabolically active, they may also influence the carbon and nitrogen cycles vital to life as we know it.
More microbes in the air would suggest more clouds. Cloud volume impacts how much heat is trapped in the atmosphere, and how much heat is reflected from the sun. The Scientist story notes researchers aren’t sure whether more clouds will heat or cool the atmosphere, but they are sure increasing clouds will impact climate one way or another. Allergy and asthma sufferers,however, can expect more misery. Rogers explains bigger plants produce more pollen, and the common allergy causing fungus alternaria alternate produces three times more spores when it feeds on the CO2 enriched plants. Airborne bacteria are also implicated in respiratory ills.
Noah Fierer, a microbial ecologist at the University of Colorado, who has been studying life in the air for years, plans to create a global map of aerial microbes. He plans to start with a survey of every part of the continental U.S. by developing a low-cost sampling devicethose volunteers in every state could use to sample bacteria in the air above their homes. He and his team also are working on plans to sample viruses and fungi in the air. He believes microbial maps will help determine the impact of urban, suburban and agricultural land use, as well as the influence of airborne microbes on weather and human health and disease.
………………………A sense sublime
Of something far more deeply interfused
Whose dwelling is the light of setting suns
And the round ocean and the living air
And the blue sky…..
…………..William Wordsworth, lines composed in 1798