New climate change research conducted at CERN offers rare, hopeful news about the planet’s resilience to global warming, finding that phytoplankton are producing far more heat-mitigating aerosols than previously understood.
In a paper recently published in Nature, the researchers reveal an unexpected picture of how clouds and aerosols have changed since the beginning of widespread fossil fuel use, offering a brighter outlook than may have been expected. The new study identifies our planet’s resilience to anthropogenic climate change, suggesting that Mother Nature may be tougher than we think.
Cloud Formation and Climate Change
Cloud condensation nuclei (CCN), tiny particles suspended in the atmosphere, are the cores around which clouds form. When the amount of aerosol particles in the atmosphere increases, they can produce a cooling effect, both by directly reflecting sunlight before it reaches the Earth’s surface and by acting as CCNs. When the number of particles available in the atmosphere for cloud formation increases, more small clouds form, which are also brighter and provide greater coverage.
Ironically, the particles formed by burning fossil fuels act in this way, mitigating the heating effect of the greenhouse gases released by the same processes, and producing a substantial offset in global warming.
Nucleation, the spontaneous condensation of trace vapors, produces more than half of the CCN in Earth’s atmosphere. The burning of fossil fuels releases sulfur dioxide, which in turn creates sulfuric acid, the most important of these nucleating vapors.
Unexpected Consequences
As emission controls have reduced atmospheric sulfur dioxide, this has created a catch-22, according to the CERN researchers. These particles are detrimental to human health, increasing the risk of lung problems and even heart disease. However, by reducing their atmospheric concentrations, these interventions are projected to increase global warming as aerosol concentrations trend back toward pre-industrial levels.
“Most climate models currently consider only sulphuric acid-driven nucleation,” explained co-author Jasper Kirkby, of the CLOUD Collaboration. “However, it is vital to understand and properly account for biogenic sources to reliably predict the Earth’s future climate and air quality. Observations over the Southern Ocean and in the upper troposphere over the Atlantic and Pacific Oceans indicate that a major source of marine aerosol particles is unaccounted for by current models.”
The CLOUD survey may finally have landed on the identity of this mysterious source. About 20% of atmospheric sulfur comes from marine phytoplankton emitting dimethyl sulfide. As that dimethyl sulfide oxidizes in the atmosphere, it then produces sulfuric acid (SA) and methanesulphonic acid (MSA). While scientists have long understood SA’s role in new particle formation, MSA was poorly understood.
Climate Change Resistance
Through a series of experiments and computer modeling, the CLOUD collaboration discovered that at temperatures below -10 °C, MSA drives particle nucleation in the presence of ammonia just as well as SA, and at temperatures below +10 °C, it drives particle growth, even with minimal ammonia.
“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,” Kirkby said. “Our model simulations indicate that MSA-driven new particle formation may account for the major missing source of marine aerosol particles in current models.”
This work provided important new knowledge to supplement CLOUD’s earlier work identifying large amounts of isoprene-driven new particle formation above tropical rainforests. Between identifying that activity over land and MSA’s newly understood marine CCN formation, CLOUD’s work suggests that the biosphere may be more resilient than previously understood, capable of creating those CCN without anthropogenic emissions to compensate for continuing global warming.
“The CLOUD Collaboration has made an important advance in our understanding of climate”, commented Gautier Hamel de Monchenault, CERN Director for Research and Computing, who was not an author on the study. “It is crucial to deepen our understanding of aerosols: in this case, increased biogenic CCN will affect estimates of the Earth’s climate sensitivity as well as projections of climate warming.”
The paper, “Role of Methanesulfonic Acid in Atmospheric Particle Nucleation and Growth,” appeared in Nature on June 24, 2026.
Ryan Whalen covers science and technology for The Debrief. He holds an MA in History and a Master of Library and Information Science with a certificate in Data Science. He can be contacted at ryan@thedebrief.org, and follow him on Twitter @mdntwvlf.