There is another living world above our own, a community of microorganisms, including bacteria, fungi, viruses, and other microscopic life form, who live in the clouds above us. Their habitat is called the aerobiome and it's the subject of Air-Borne: The Hidden History of the Life We Breathe, a new book by esteemed science writer Carl Zimmer. But where do these creatures come from? Mostly, from the ground below where the ocean, forests, dust storms, fires toss more than 100,000 tons of bacteria cells and 50 million tons of fungal spores into the air every year.
From an excerpt of Air-Borne in Smithsonian:
By one estimate, a single square meter of ground may be pelted with 100 million bacteria during every hour of a rainstorm.
While the aerobiome is transient, scientists now recognize it as a distinct zone of life, one that follows its own ecological rules and that exerts a powerful influence on the planet below[…]
Above the Earth's clouds, the aerobiome ebbs into the unknown. In 1935, American explorers piloted a balloon called Explorer II to the stratosphere. They captured bacteria and fungal spores from the black sky 12 miles above Earth's surface. In the decades since, a few teams of scientists have searched at even higher altitudes. In 1974, Soviet scientists fired rockets from the steppes of Kazakhstan into the upper atmosphere. The rockets broke apart to release sterile microbe traps. The traps parachuted down to Earth, and inside them the scientists found bacteria and fungi. One of their four rockets found life 48 miles above the planet, three times higher than the record setting high-altitude balloon Explorer II reached in 1935. Aerobiologists today are leery about embracing that record. The Soviet rockets actually went beyond the stratosphere to another layer, called the mesosphere, where meteors falling toward Earth burn into shooting stars. It hardly seems like a place where life could endure. But more recent studies have confirmed findings that the stratosphere is alive. Over the years, NASA has launched a number of balloons that have found life as high as 25 miles.
Previously:
• Atmosphere of exoplanet is found to be indicative of an ocean surface… and maybe, possibly life
