MétéoSuisse Station aérologique Ch. de l’Aérologie CP 316 CH -1530 Payerne Suisse
- Key words: climate, hypersensitivity, pollen
- DOI : 10.1684/ers.2008.0177
- Page(s) : 431-4
- Published in: 2008
Weather and climate factors influence the development of vegetation and airborne pollen. Changes affecting these factors have both direct and indirect consequences for plant distribution and phenology and thus for the production, release and dispersion of pollen. Clear trends linked to climate warming show earlier flowering of late winter and spring species, a longer summer pollen season (e.g., grasses) and increased quantities of pollen in late summer. Climate warming also leads to the northward extension of the distribution area of Mediterranean plants with allergenic pollen (e.g., pellitory). Many other factors influence pollen production and dispersion. Human intervention in the environment plays an important role, through both extensive planting and accidental introduction of many plant species with allergenic pollen. At a local or regional scale, land use often influences pollen exposure more than climate change. For example, urbanization and changes in agricultural practices considerably modify the distribution of plants in an area and thus the quality, quantity and frequency of pollen exposure. One important concern is the rapid extension of the distribution area of some invasive plants, short ragweed in particular: climate change and human activities jointly support its spread and pollen production. Ragweed seeds are spread through soil transport and moving vehicles, contaminated seeds, construction, etc. Climate warming promotes open vegetation and the creation of ecological niches for ragweed. In addition, increasing CO
2 concentrations and temperatures increase pollen production and prolong its flowering period.