Microbes found at extreme altitudes could influence precipitation and cloud density.
Ravaged by arid winds and ultraviolet rays, some bacteria not only survive in the upper atmosphere but might affect weather and climate, according to a study published on 28 January in the Proceedings of the National Academy of Sciences1.
In one of the first attempts to explore atmospheric microbiology at high altitude, researchers analysed air samples from a six-week hurricane-research mission by NASA in 2010. A total of 314 different types of bacteria were collected in air masses around 10 kilometres above the Gulf of Mexico, the Caribbean Sea, the Atlantic Ocean, and the continental United States. Although the scientists trapped only a small amount of material, bacteria accounted for around 20% of all particles — biological and non-biological — a higher proportion than in the near-Earth atmosphere.
“I’m really, really surprised at the high bacterial density at these high altitudes,” says Ulrich Karlson, an environmental microbiologist at Aarhus University in Denmark, who was not involved in the study. “This is clearly a harsh environment.”
“One of the next challenges is to figure out the role of these organisms,” says Konstantinos Konstantinidis, an environmental microbiologist at the Georgia Institute of Technology in Atlanta and one of the study's authors.