Climate Change and Microorganisms in the Lower Atmosphere Rising temperatures: Natural balance in the troposphere in danger

The Institute of Flight Guidance at Technische Universität Braunschweig has taken part in a research series in which researchers at the Nanyang Technological University in Singapore investigated the presence of microorganisms in the altitude band up to 3,500 metres. The main results of these investigations show that the bacteria and fungal spores in the lower atmosphere, the troposphere, have a very specific distribution and are strongly dependent on the prevailing temperatures. The higher air temperatures caused by global warming will affect these bacterial and fungal spore populations and thus also permanently disrupt the natural balance that has been established over thousands of years.

Atmospheric microorganisms consist of bacteria and fungal spores. Most of these remain in the free atmosphere once they have been transferred from the earth’s surface into the air. Only fractions of these microorganisms return to Earth, for example with raindrops.

“The study results show a vertical distribution of microorganisms in the Earth’s atmosphere,” says Professor Stephan Schuster, the lead researcher of the study from the Singapore Centre for Environmental Life Sciences Engineering (SCELSE) at Nanyang Technological University in Singapore. “We can show that the composition of microorganisms in our atmosphere is solely dependent on temperature. Rising air temperatures, caused by the global rise in temperature, will permanently disrupt this composition and distribution of microorganisms. These changes can become a problem for humans and nature.”

The now discovered vertical distribution of microorganisms and their temperature dependencies will be a starting point for further studies to investigate the effects on humans and nature, for example in food production, and to develop suitable countermeasures.

During the series of investigations, which took place in autumn 2018, TU Braunschweig’s research aircraft, the Dornier Do128-6 “D-IBUF”, was used for measurements at different altitudes (from 300 metres to 3500 metres above ground). “We carried out the measurement flights, organised the corresponding equipment and permit, and assisted with the planning from a meteorological point of view,” says Dr Thomas Feuerle from TU Braunschweig.

During the flights, so-called “air mass filters” were used to collect the biomass in the respective air layers during flights during the day and at night. Identical air mass filters were used in parallel and synchronised on a 200-metre high measuring mast at the Karlsruhe Institute of Technology (KIT). A total of 480 air samples were collected in Germany and subsequently analysed in Singapore. A surprising finding was that the composition of the microorganisms was constant at altitudes higher than about 1000 metres, regardless of day or night. More than 10,000 different species of bacteria and fungi were identified at these altitudes. The composition at such high altitudes was very different from the composition of the air layers close to the Earth (up to about 300 metres altitude). This composition varied greatly between day and night.

The study results were published at the beginning of February 2022 in the journal “Proceedings of the National Academy of Sciences of the United States of America (PNAS)” by the interdisciplinary team of scientists led by Professor Stephan Schuster.