Periodic Reporting for period 4 - CHAPAs (Chasing pre-industrial aerosols)
Période du rapport: 2024-07-01 au 2024-12-31
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.
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.
The core of the project was to perform comprehensive and advanced observation in remote and pristine location around the world. Those type of measurements usually require sophisticated logistic preparation and because of COVID this was not really possible until late and therefore we had to adjust our plan to what it was possible. Despite all of that we were still able to perform several measurements and when not possible analyses older data. During the COVID outbreak we have used the situation to better understanding how aerosol sources changed. We have performed a measurement campaign in North Italy, an area that has been heavily affected by the COVID outbreak followed by lock-down policies. In addition to those measurements we have performed measurements at the Izana station, Tenerife, Canary Island at 2400 m. Here the data analysis has just started and the results will be published in the next years.
Through a series of high-impact field studies conducted in the Himalayas (Nature Geoscience, 2021), the Andes/Amazon Basin (National Science Review, 2023), and Finnish peatlands (Science Advances, 2024), it was demonstrated that:
• Biogenic volatile organic compounds (BVOCs) were the primary precursors for new particle formation (NPF) in pristine environments.
• Highly oxidized organic molecules (HOMs) played a dominant role in forming particles without sulfuric acid involvement.
• These natural processes are critical for understading aerosol in the pre-industrial period.
The collective findings highlight that organic-driven aerosol formation must be considered as a major natural mechanism when modeling historical and future climates.
The scientific knowledge generated by the project is being exploited by:
• Improving global climate models by integrating natural aerosol formation mechanisms into their frameworks (e.g. CMIP7 and IPCC model refinements).
• Guiding climate policymakers by providing better estimates of natural climate variability and aerosol-cloud interactions.
• Preparing environmental agencies for possible atmospheric changes as global pollution levels decrease.
• Informing strategies to mitigate future climate risks by understanding the full role of natural aerosol dynamics.
The project’s results have been widely disseminated through:
• Peer-reviewed publications in top journals (Nature Geoscience, Science Advances, National Science Review), with several studies featured on journal covers.
• Many International conference, seminars and invited keynote talks, sharing insights with atmospheric scientists, policymakers, and the public.
• Public communication via interviews, press releases, and outreach articles (e.g. Times of India, Scientific American), promoting societal understanding of climate science.
• Educational activities, including teaching and mentoring at the University of Helsinki, embedding the findings into the next generation of climate researchers.
• Collaborations with major international research projects and networks (e.g. CLOUD at CERN, global atmospheric monitoring stations).
Through a series of high-impact field studies conducted in the Himalayas (Nature Geoscience, 2021), the Andes/Amazon Basin (National Science Review, 2023), and Finnish peatlands (Science Advances, 2024), it was demonstrated that:
• Biogenic volatile organic compounds (BVOCs) were the primary precursors for new particle formation (NPF) in pristine environments.
• Highly oxidized organic molecules (HOMs) played a dominant role in forming particles without sulfuric acid involvement.
• These natural processes are critical for understading aerosol in the pre-industrial period.
The collective findings highlight that organic-driven aerosol formation must be considered as a major natural mechanism when modeling historical and future climates.
The scientific knowledge generated by the project is being exploited by:
• Improving global climate models by integrating natural aerosol formation mechanisms into their frameworks (e.g. CMIP7 and IPCC model refinements).
• Guiding climate policymakers by providing better estimates of natural climate variability and aerosol-cloud interactions.
• Preparing environmental agencies for possible atmospheric changes as global pollution levels decrease.
• Informing strategies to mitigate future climate risks by understanding the full role of natural aerosol dynamics.
The project’s results have been widely disseminated through:
• Peer-reviewed publications in top journals (Nature Geoscience, Science Advances, National Science Review), with several studies featured on journal covers.
• Many International conference, seminars and invited keynote talks, sharing insights with atmospheric scientists, policymakers, and the public.
• Public communication via interviews, press releases, and outreach articles (e.g. Times of India, Scientific American), promoting societal understanding of climate science.
• Educational activities, including teaching and mentoring at the University of Helsinki, embedding the findings into the next generation of climate researchers.
• Collaborations with major international research projects and networks (e.g. CLOUD at CERN, global atmospheric monitoring stations).
This project has advanced the state of the art by providing the first direct, field-based evidence of natural new particle formation (NPF) in pristine environments resembling pre-industrial conditions. While earlier studies mainly relied on laboratory experiments or observations in polluted regions, this work demonstrated that highly oxidized organic molecules can drive aerosol formation without sulfuric acid, fundamentally revising our understanding of atmospheric processes before industrialization. By combining unique field data from the Himalayas, Andes, and Finnish peatlands, the project has redefined the natural aerosol baseline, offering critical corrections for global climate models. It connects real-world observations with theoretical and laboratory studies, setting a new standard for atmospheric science.
In this project we have:
- Finalized comparative analyses across all studied regions.
- Publish high-impact papers and datasets.
- Trained new experts in atmospheric field research.
- Enhanced public and policy understanding of natural climate mechanisms.
Ultimately, the project provided a new, empirically grounded foundation for modeling the Earth's past and future climate.
In this project we have:
- Finalized comparative analyses across all studied regions.
- Publish high-impact papers and datasets.
- Trained new experts in atmospheric field research.
- Enhanced public and policy understanding of natural climate mechanisms.
Ultimately, the project provided a new, empirically grounded foundation for modeling the Earth's past and future climate.