BACTERIA, IT SEEMS, can get everywhere: even hostile environments such as Antarctic lakes and deep-sea volcanic vents are home to the tiny creatures.
Now, scientists in the US have found microbes high up in the atmosphere, a discovery that suggests bacteria could play a more significant role in our weather than was previously thought.
In 2010, NASA sent out a fleet of aircraft to study the atmosphere before, during, and after hurricanes over the Caribbean and the Gulf of Mexico. This provided researchers with the perfect opportunity to collect air samples from the troposphere, the portion of the atmosphere around 8-10km (5-6 miles) above the Earth’s surface. Analyzing the samples back in the lab, the researchers found a veritable zoo of bacteria – 314 types in total.
“We weren’t expecting to find so many bacteria,” says Prof Athanasios Nenes at the Georgia Institute of Technology. “What was even more surprising was that more than 60 per cent of them were alive. This environment poses big challenges for life – freezing temperatures, scarce food and high UV radiation – but these bacteria manage to survive.”
The researchers aren’t yet sure whether bacteria actually live and reproduce in the atmosphere, or whether they’re just being whisked up by the winds – especially since air masses over oceans were found to host mostly marine bacteria, while terrestrial bacteria were found predominantly in air masses over land. Nevertheless, these sky-high microbes are of great interest to climate scientists because they could act as nuclei around which icy clouds form.
“Based on the sheer number of bacteria we’ve seen, they may be having an impact on the clouds up there, which could in turn affect the Earth’s energy balance that drives weather and climate,” says Nenes. “There are climate modellers who are now interested in including a biological particle cycle in their models. This would give us a better idea of whether these microbes really can alter the climate.” By JAMES LLOYD