Atmospheric amines are a crucial yet missing link in Earth's climate via airborne aerosol production.

Atmospheric amines, derivatives of ammonia, play a unique yet not fully understood role in air quality, climate and public health. Sub-5 parts per trillion Volume (pptV, <10^-12 in volume) mixing ratios of amines facilitate the physical and/or chemical transformation of aerosols in the atmosphere, enhancing aerosol formation and growth rates, aerosol hygroscopicity, and the activation of cloud condensation nuclei. This serves as the initial step for cloud droplet formation and, consequently, influences cloud properties and the hydrological cycle. Ambient observations demonstrate more than a thousand-fold particle formation rates in the presence of amines as compared to ammonia. Yet, the challenges related to detecting minute levels of amines, the paucity of ambient amine measurements, and the limited process-based understanding of airborne aerosol production have resulted in amines being underrepresented in global climate models. Therefore, advanced techniques with extremely low detection limits and highly spatially and temporally resolved ambient amine measurements globally in diverse environments are essential.