Objective: We sought to examine the spatiotemporal patterns of change of weeds (ragweed, mugwort), trees (birch, oak), grasses in multiple climate regions, and their relationships with the changing climate in the contiguous US over time from the year 1994 to 2010.
Methods: Regional assessments (South-S, Southeast-SE, Southwest-SW, Central-C, West-W, Northeast-NE, Eastnorthcentral-ENC, Westnorthcentral-WNC and Northwest-NW) for land area coverage, pollen season timing, hourly pollen concentrations, due to CC were obtained using statistical analyses and deterministic simulation based on observed and simulated models across the CONUS.
Results: The allergenic pollen seasons of representative trees, weeds and grasses during the 2000s across the CONUS have been observed to start 3.0 (95% Confidence Interval [CI], 1.1-4.9) days earlier on average than in the 1990s. The average peak value and annual total of daily counted airborne pollen have increased by 42.4% (95% CI, 21.9%- 62.9%) and 46.0% (95% CI, 21.5%-70.5%), respectively. Changes of ragweed pollen season timing and levels were identified as functions of latitude, and associated with changes of Growing Degree Days, Frost Free Days and precipitation.
Conclusion: These changes are likely due to recent climate change and particularly the enhanced warming and precipitation at higher latitudes in the CONUS. The observed pollen season start date, season length and airborne pollen level could be correctly predicted using Bayesian and machine learning models based on the locally observed meteorological factors.