Anthropogenic climate change is worsening North American pollen seasons

TLDR

Airborne pollen has major respiratory health impacts and anthropogenic climate change may increase pollen concentrations and extend pollen seasons. The study aims to formally detect and attribute the influence of anthropogenic climate change on continental North American pollen seasons. We analyze 821 site‑years of pollen records from 60 North American stations (1990‑2018) alongside Earth system model simulations to quantify human‑caused climate change effects on pollen patterns. We find widespread advances and lengthening of pollen seasons (+20 d) and increases in pollen concentrations (+21 %) across North America, strongly coupled to observed warming, with human forcing contributing ~50 % of the season trend and ~8 % of the concentration trend, indicating that anthropogenic climate change has already exacerbated pollen seasons in the past three decades with deleterious respiratory health effects.

Abstract

Airborne pollen has major respiratory health impacts and anthropogenic climate change may increase pollen concentrations and extend pollen seasons. While greenhouse and field studies indicate that pollen concentrations are correlated with temperature, a formal detection and attribution of the role of anthropogenic climate change in continental pollen seasons is urgently needed. Here, we use long-term pollen data from 60 North American stations from 1990 to 2018, spanning 821 site-years of data, and Earth system model simulations to quantify the role of human-caused climate change in continental patterns in pollen concentrations. We find widespread advances and lengthening of pollen seasons (+20 d) and increases in pollen concentrations (+21%) across North America, which are strongly coupled to observed warming. Human forcing of the climate system contributed ∼50% (interquartile range: 19-84%) of the trend in pollen seasons and ∼8% (4-14%) of the trend in pollen concentrations. Our results reveal that anthropogenic climate change has already exacerbated pollen seasons in the past three decades with attendant deleterious effects on respiratory health.