Pollen is not only known for triggering allergies; it also has a notable impact on the local climate. This is especially true during spring when a significant amount of pollen is released, which aids in forming ice in clouds, potentially leading to increased rainfall.
Research conducted through both ground-based and satellite observations in the United States indicates that higher pollen levels in spring correlate with increased cloud ice and more rainfall, even when temperatures range from minus 15 to minus 25 degrees Celsius. “Our laboratory findings confirm that pollen serves as an ice nucleus; this affects the freezing point of water in clouds and promotes precipitation,” explains meteorologist Dr. Jan Kretzschmar, the primary researcher of the study. Water in clouds typically freezes only at temperatures lower than minus 38 degrees Celsius without these ice-nucleating particles (INPs).
“Within the Breathing Nature Cluster of Excellence project, we sought to determine whether this phenomenon could be observed outside laboratory settings, and how it’s influenced by climate change and loss of biodiversity,” states co-author Professor Johannes Quaas, who is a Professor of Theoretical Meteorology at Leipzig and a spokesperson for the Breathing Nature consortium.
Regional and Seasonal Importance
Globally, the impact of pollen on ice formation is relatively minor compared to elements like dust; however, its significance grows on regional and seasonal levels. Particularly during spring, vast quantities of pollen ascend into the atmosphere, reaching chilly air layers. Kretzschmar elaborates: “Due to its size, pollen tends to linger in the atmosphere for a limited duration. Our research emphasizes the significance of smaller pollen fragments, which are generated when pollen bursts in humid conditions. These smaller particles can remain airborne for longer periods and, in large enough numbers, reach colder atmospheric layers where they instigate ice formation.”
Climate Change Magnifies Pollen’s Effects — Biodiversity as a Crucial Element
Human-induced climate change is altering the timing of pollen seasons, extending their duration and raising pollen levels in the air. Predictions suggest these trends will intensify by the century’s end, potentially resulting in more frequent and severe local rainfall.
The research also highlights the role of biodiversity. Numerous plant species release significant amounts of pollen simultaneously each spring, influencing cloud development and the quantity of ice particles in the atmosphere. Understanding these interactions demands further investigation to grasp pollen’s influence on climate change and effectively integrate this knowledge into future climate models. “By accurately simulating pollen’s effects and its relationship with climate, we can enhance the precision of our predictions,” concludes Kretzschmar.
