Unveiling the Role of Bioaerosols in Climate Processes: A Mini Review

Bioaerosols influence the climate processes, human health and overall ecosystem. Their type, concentration and diversity have important implications on various atmospheric processes however the limited understanding of bioaerosols-cloud-climate connection has resulted in existing uncertainty in climate models. Bioaerosols as ice nucleating particles (INPs) and cloud condensation nuclei (CCN) govern precipitation initiation, cloud formation and thus the complex hydrological cycle. Homogeneous nucleation takes place at colder temperatures (< − 38 ℃), while owing to their unique properties, certain ice nucleating bioaerosols can initiate freezing at much warmer temperatures (≧ − 10 °C) and thus are important for precipitation initiation through heterogenous nucleation mechanism. Flux of bioaerosols from diverse terrestrial and marine sources lead to their build-up in the atmosphere but rare bioaerosols act as CCN and INP. These rare characteristics of bioaerosols remain largely unexplored and need further attention and research. This work presents fundamental insights on the role of bioaerosols in cloud formation and ice nucleation mechanism along with an overview on the types, diversity and sources of bioaerosols. Most studies reviewed here on bioaerosol-cloud-climate connections are restricted to from specific research groups. Bioaerosol research is still in evolving stage and limited usage of advanced techniques of sampling and characterization is noticed particularly in developing countries. Lack of even baseline database on bioaerosols has resulted in poor understanding of their implications. The discussion presented here on species level information of cloud forming and ice nucleating bioaerosols will help researchers in developing fundamental understanding on characteristics and implications of bioaerosols. Bioaerosol research is expensive and thus joint campaigns by researchers from interdisciplinary areas should be encouraged. Application of high-throughput sequencing allows rapid taxonomic identification and such modern molecular methods should be routinely used for understanding implications of bioaerosols on climate as well as human health.