Impacts of climate change on allergenic pollen production: A systematic review and meta-analysis.

• The study focuses on 11 major allergenic taxa including Poaceae, Betula, Olea, Artemisia , Urticaceae, Cupressaceae, Alnus, Corylus, Platanus, Morus , and Fraxinus. • vast majority of studies have been conducted in Europe, particularly in southern Europe. • Alnus has a positive trend in APIn and a consistent increase in pollen concentrations from 1974 to 2020. • Accumulated rainfall and mean air temperature during flowering and preceding months exhibit different relationships with APIn. • Betula and Cupressaceae, exhibit a negative correlation between API and mean air temperature during the flowering period. • Changes in temperature and rainfall highly impact the flowering conditions and seasonal pollen concentration of anemophilous Mediterranean species. Climate change has been identified as a major driver of alterations in pollen production, with potential implications for allergenic diseases and ecosystems. This systematic review and meta-analysis examine the impacts of global warming on the Annual Pollen Integral (APIn), a measure of pollen production, across multiple plant species. We conducted a comprehensive literature review and selected studies based on predetermined inclusion criteria. Our analysis covered 11 major allergenic taxa (Poaceae, Betula, Olea, Artemisia , Urticaceae, Cupressaceae, Alnus, Corylus, Platanus, Morus , and Fraxinus), with a focus on long-term trends in the relationship between temperature and APIn. The results revealed a generalized increase in APIn over the study period (1974–2020) for most taxa. Notable exceptions were Urticaceae and Artemisia , which exhibited a generalized decrease. Our analysis also highlighted a varying start and end years for the time series studies, ranging from 1974 in the United Kingdom to 2020. The earliest series were from Belgium, Italy, and the UK, while the most numerous studies were from Spain and Poland. Subsequent analysis of the impact of environmental parameters on APIn revealed complex patterns. Accumulated rainfall and mean air temperature during flowering and preceding months exhibited different relationships with APIn depending on the taxa and the period considered. These findings underscore the complex impacts of climate change on pollen production, with significant variations across different plant species and regions. [ABSTRACT FROM AUTHOR]