Full Breakdown
New Marine Aerosol Source Unveiled: MSA Drives Particle Formation in Cold Oceans
6/26/2026, 11:35:43 AM
Core Discovery
Experiments in the CERN CLOUD chamber showed methanesulfonic acid (MSA) nucleated with ammonia below –10 °C at rates comparable to sulfuric acid (SA)–NH3. Mixed SA-MSA vapors raised nucleation up to tenfold and particle growth up to twofold versus SA-NH3 alone, and sustained rapid growth from –10 °C to +10 °C even with trace ammonia.
Context
Marine phytoplankton emit dimethyl sulfide (DMS), supplying ~20 % of atmospheric sulfur and oxidising to SA and MSA in similar amounts. The study was led by the CERN CLOUD Collaboration, with spokesperson Jasper Kirkby, and involved Dr Jiali Shen, Dr Xu-Cheng He, Prof Katrianne Lehtipalo, CERN Director Gautier Hamel de Monchenault, and colleagues from the University of Helsinki and INAR.
Implications
Aerosol particles serve as cloud condensation nuclei (CCN); higher CCN generally brighten clouds and cool the climate. Simulations show that adding MSA can raise CCN most strongly over the Arctic and Antarctic, where current models underestimate CCN by >50 %. Excluding MSA-driven nucleation thus produces a systematic warm bias, especially over the Southern Ocean.
Official Statements
The collaboration notes that most climate models consider only SA-driven nucleation, overlooking a major biogenic pathway. Researchers stress that incorporating MSA processes is essential for reliable climate and air-quality forecasts.
Criticism
Current models underestimate CCN over the Southern Ocean, creating a warm bias and underscoring the need to revise them to include biogenic MSA contributions.
Gaps
Laboratory and modelling results agree on MSA’s effectiveness, yet direct atmospheric measurements of MSA-driven nucleation are scarce, leaving the real-world impact uncertain.
Verbatim Quotes
- “Since MSA and SA generally coexist at similar concentrations in cool marine regions, our findings indicate that particle nucleation rates might be accelerated up to tenfold and growth rates up to twofold compared with sulphuric acid and ammonia alone” — Jasper Kirkby, spokesperson, CLOUD Collaboration
- “Because MSA and sulfuric acid generally occur at similar concentrations over cold ocean regions, clouds may form there up to ten times faster than previously thought” — Dr Jiali Shen, lead author
- “The CLOUD Collaboration has made an important advance in our understanding of climate” — Gautier Hamel de Monchenault, CERN Director for Research and Computing
- “As emissions of sulfur dioxide from fossil fuels continue to decline, the natural, biological sources of cloud seeds from marine plankton may be more effective in the climate system. Capturing these processes is essential if we are to reliably predict future climate” — Dr Xu-Cheng He and Professor Katrianne Lehtipalo, corresponding authors
Next Steps
The authors advise adding MSA nucleation pathways to global climate models and expanding field campaigns to validate laboratory findings.
