Influence of climate warming and land-cover change on aerobiological pollen season in Estonia

Abstract

Abstract Pollen allergy is an increasing public health concern in Europe, as climate warming alters flowering phenology and airborne pollen dynamics. This study analysed temporal and spatial changes in pollen seasons in Estonia using aerobiological monitoring data from Tartu, Tallinn, and Pärnu. Temporal changes were assessed by comparing two monitoring periods in Tartu (1990–1998 and 2012–2022), while spatial differences were evaluated across stations in contrasting climatic settings. Annual mean air temperature in Tartu increased by 1.1 °C between the two study periods, with the strongest warming occurring in winter and early spring. The results demonstrate a clear advancement of flowering phenology in early-spring taxa. The 1st day of intensive birch ( Betula ) flowering advanced by approximately 4 days in Tartu, while alder ( Alnus ) flowering began substantially earlier in warm years, with the first intensive pollen episodes occurring up to 23 days earlier than during the 1990s. Inland Tartu consistently exhibited higher and longer-lasting pollen concentrations than the coastal sites of Tallinn and Pärnu. Statistical modelling showed that flowering onset can be predicted with moderate to very high accuracy using temperature-related variables. The best-performing models included mean temperature and daily degrees above 5 °C (DD5), while precipitation was not a significant predictor. Model prediction uncertainty ranged from 1 to 8 days depending on taxon. These findings highlight the need for updated pollen calendars and continuous aerobiological monitoring under ongoing climate warming. Sustained funding is essential to ensure timely and spatially representative pollen information, particularly in small countries where monitoring networks remain vulnerable to financial constraints.

The authors' abstract, as published at the source. Aerobiologia, 2026 · DOI ↗