Life in the Storm

Live microbes may play an important role in the evolution of hurricanes, a new study has found. An analysis of the material collected from Hurricanes Earl and Karl by researchers at Georgia Institute of Technology in 2010 has found that up to 20% of it may be composed of microbes. Like dust, the microbes act as surfaces for ice crystals to form on – or “seed” – which ultimately aids in the development of a hurricane.

The bacteria probably originated hundreds of kilometres away, swept up by the wind from the land, soil, or ocean surface. High up in the troposphere these microbes would be subject to extreme conditions: sub-zero temperatures, low oxygen, and high levels of UV radiation from the Sun. In spite of this, entire communities of them appear to be living in the clouds and even thriving. Over 60% of those discovered by the Georgia Tech team were alive.

The findings could have profound implications on how scientists look at global biological cycling. “It just opens more questions about how many bacteria might survive this rough atmospheric treatment and continue the ubiquitous spread of organisms around the planet’s surface,” Dr Jack Gilbert, a microbiologist at the University of Chicago, told National Geographic.

Interestingly, the microbes may not be entirely passive in the process either. Some of the species discovered have a protein on their surfaces which lock molecules of water together helping with the formation of ice crystals. This opens up the possibility that bacteria could be used in the future to induce cloud seeding in drier areas. Previously, particles of silver iodide have been injected into the atmosphere to induce rainfall. The bacteria, however, may be able to form ice crystals at higher temperatures, suggesting they may be more effective than the silver iodide.

Atmospheric modeling has previously only looked at things from a physics perspective. Biology, it seems, may be equally important.