Tiny airborne organisms like pollen and bacteria may be the hidden catalysts behind heavy rainfall and snowstorms, prompting scientists to rethink climate models.
Key Points at a Glance
- Biological particles such as pollen, bacteria, and spores can induce ice formation in clouds.
- These particles’ concentrations fluctuate with temperature changes, peaking during warmer periods.
- Current climate models often overlook the impact of biological particles on precipitation.
- EPFL’s CHOPIN campaign aims to identify which biological particles most effectively trigger cloud formation.
In a groundbreaking study, scientists from the École Polytechnique Fédérale de Lausanne (EPFL) have unveiled the significant role that biological particles play in cloud formation and precipitation. Traditionally, cloud formation has been attributed to inorganic particles like dust and sea salt. However, this new research highlights that organic particles—such as pollen, bacteria, fungal spores, and plant debris—are exceptionally efficient at initiating ice formation in clouds.
The process of ice formation is crucial because ice crystals fall rapidly from clouds, leading to precipitation. Intense ice formation is often associated with extreme weather events, including heavy rainfall and snowstorms. The study emphasizes that the concentration of these biological particles in the atmosphere varies throughout the day, typically peaking during warmer periods when biological emissions from forests and other ecosystems are at their highest.
Lead researcher Athanasios Nenes and postdoctoral fellow Kunfeng Gao conducted their study at Mount Helmos in Greece, an alpine region characterized by frequent cloud cover and influenced by emissions from surrounding forests. Their observations revealed a strong correlation between the number of biological particles and the occurrence of ice-nucleating particles in the atmosphere. This diurnal pattern suggests that biological emissions significantly contribute to cloud formation and subsequent precipitation.
Despite these findings, current meteorological and climate models often neglect the influence of biological particles on cloud dynamics and precipitation patterns. This oversight could lead to inaccuracies in weather forecasting and climate projections, especially as the concentration of biological particles is expected to increase with global warming.
To address this gap, EPFL has initiated the CHOPIN (Clouds, Hydrometeors, and Precipitation: Organics and INorganics) campaign. This project employs advanced instrumentation, including cloud radars, aerosol lidars, unmanned aerial vehicles (UAVs), and tethered balloons, to collect and analyze atmospheric samples. The goal is to identify which biological particles are most effective at inducing cloud droplet and ice formation, thereby enhancing the accuracy of weather and climate models.
Nenes, who also contributes to the Intergovernmental Panel on Climate Change (IPCC), underscores the importance of incorporating these findings into climate assessments. As our understanding of the atmosphere evolves, acknowledging the role of biological particles is essential for improving predictions of extreme weather events and informing mitigation strategies.
