From trees to rain: Enhancement of cloud glaciation and precipitation by pollen

TL;DR

This study demonstrates that increased pollen concentrations in spring enhance cloud ice fraction and precipitation frequency, suggesting pollen's significant role in cloud glaciation and climate modulation.

Contribution

It provides the first large-scale observational evidence linking pollen levels to cloud ice and precipitation changes, highlighting pollen's impact on climate processes.

Findings

Higher pollen levels correlate with increased cloud ice fraction.

Enhanced pollen concentrations lead to more frequent precipitation.

Pollen season extension may influence regional climate and precipitation patterns.

Abstract

The ability of pollen to enable the glaciation of supercooled liquid water has been demonstrated in laboratory studies; however, the potential large-scale effect of trees and pollen on clouds, precipitation and climate is pressing knowledge to better understand and project clouds in the current and future climate. Combining ground-based measurements of pollen concentrations and satellite observations of cloud properties within the United States, we show that enhanced pollen concentrations during springtime lead to a higher cloud ice fraction. We further establish the link from the pollen-induced increase in cloud ice to a higher precipitation frequency. In light of anthropogenic climate change, the extended and strengthened pollen season and future alterations in biodiversity can introduce a localized climate forcing and a modification of the precipitation frequency and intensity.