Aerosol particles affect climate by interacting with solar radiation and acting as cloud condensation nuclei (CCN), but their overall impact remains a major uncertainty in climate science. About 45% of the variance in aerosol forcing stems from uncertainties in natural emissions, highlighting the need to understand pristine, pre-industrial atmospheres where only natural aerosols existed. This baseline is crucial for distinguishing natural variability from human-induced climate change. A major challenge is understanding how new particles formed naturally, especially through new particle formation (NPF)—the process where tiny particles grow into CCN. Research, including CERN's CLOUD project and high-altitude campaigns, shows that in clean environments, organic molecules, rather than sulfuric acid, drive particle formation. These insights underscore the need to refine climate models by better understanding natural aerosol processes. Although natural emissions don’t directly produce radiative forcing, they set the baseline for measuring anthropogenic impacts. Industrial pollution today obscures natural processes that once regulated cloud properties and climate. Misrepresenting natural aerosol formation risks underestimating future warming, leading to ineffective climate policies and inadequate environmental preparation.
This project aims to reconstruct pre-industrial particle formation by:
- Identifying NPF mechanisms in pristine regions like the Himalayas, Andes, Finnish peatlands, and open oceans.
- Studying how biogenic emissions drive particle formation without industrial pollutants.
- Quantifying the impact of organic vapor nucleation on aerosol populations.
- Using observations to reconstruct pre-industrial atmospheres and predict future changes as pollution declines.
This project successfully uncovered how aerosol particles, crucial for cloud formation and climate regulation, were naturally formed in the pre-industrial atmosphere, before significant human interference. Through pioneering field studies conducted in some of the most pristine regions on Earth — the Himalayas, the Andes, and Finnish peatlands — the research demonstrated that organic molecules from biogenic sources were the main drivers of new particle formation (NPF) in a clean atmosphere, without reliance on modern pollutants like sulfuric acid.
The findings revealed that:
• Organic-driven aerosol formation was an important natural process shaping Earth’s atmosphere and climate prior to industrialization.
• These processes are still observable today in isolated environments, providing living laboratories for reconstructing past atmospheric conditions.
• Modern climate models must integrate these natural formation pathways to more accurately simulate historical, present, and future climate scenarios.
The project not only deepened scientific understanding of atmospheric particle dynamics but also provided critical baseline data necessary to:
• Improve global climate predictions,
• Inform international climate policies,
• Guide future environmental protection efforts as societies move toward cleaner, low-emission futures.
