- Preprint Article
1
- 10.21203/rs.3.rs-7606687/v1
Climate warming and drying drive shifts in grass pollen phenology at a Sentinel Southern Hemisphere site
- Sep 16, 2025
- Research Square
- Ha Nguyen + 4 more +4
Abstract Climate change is extending pollen seasons and intensifying exposure with major consequences for respiratory health. While extensive long-term pollen records are available in the Northern Hemisphere, comparable datasets remain scarce in the Southern Hemisphere, limiting global assessments of climate impacts. Here, we presentnearly three decades of observations from the longest-operating pollen sampler in the Southern Hemisphere, located in southeast Australia—a region experiencing pronounced warming and drying. We found the peak grass pollen period advancing by 8.7 days per decade (p < 0.01), concurrent with earlier spring warming and advancing greenness phenology measured from satellites. There was a substantial redistribution in pollen fraction loadings from austral summer to austral spring. Yet, despite a lengthened grass pollen season of approximately 7 days per decade (p < 0.01), total and peak pollen concentrations have declined several-fold, consistent with a climate-related drying trend. These unique records provide rare insight into the climate sensitivity of grass pollen phenology under contrasting climate trajectories. The complex interplay between climate factors and pollen dynamics may extend the period of allergic sensitization even as overall pollen levels fall, highlighting the need to better understand climate change impacts on pollen seasons for adaptive public health strategies.
Read more