Marine organisms impact sea spray ice formation potential

Over the oceans, breaking waves and wind can loft sea spray aerosols (SSA) high enough into the atmosphere to reach clouds where they can form ice and influence their role in modulating the Earth's radiation and water balances. Using micro-spectroscopic analyses we examined individual ice-forming particles finding that they are made up of the metabolic products of microorganisms living near the ocean surface which they release into the seawater. These exudates are identified as the ice-nucleating agents in SSA. Using our results and data from other studies we developed a freezing model to predict ice-forming particles from SSA. As SSA is globally one of the most abundant aerosol species, our findings are critical for how ice formation is represented in cloud models to assess climate sensitivity.

Reference: Alpert, P.A., Kilthau, W.P., O'Brien, R.E., et al., (2022). Ice-nucleating agents in sea spray aerosol identified and quantified with a holistic multimodal freezing model. Sci. Adv., 8, eabq6842. https://doi.org/10.1126/sciadv.abq6842