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From Molecular processes to Climate: The cycle of organic matter in Atmospheric Aerosols

Final Activity Report Summary - OMAA (From Molecular Processes to Climate: The Cycle of Organic Matter in Atmospheric Aerosols)

The main cooling contributions to Earth's climate, opposing the warming effects of greenhouse gases, are those of atmospheric aerosols and clouds. The general objectives of OMAA was to study chemical transformations and properties of organic matter in aerosols that would affect these important climate contributions by affecting the composition and optical properties of aerosols or their efficiency in forming cloud droplets. The results obtained during OMAA led to ground-breaking advances on these topics:

One direction of research focusing on the role of bio-organisms in cloud formation identified some microbial substances as the most efficient cloud-forming material ever studied, even better than inorganic salts, believed to be the main cloud-forming material in the atmosphere until now. These microbial substances were found in different aerosols and at concentrations large enough to make these aerosols more efficient in forming cloud droplets than any other particles. These results might fundamentally change the understanding of these processes by identifying 'triggers' for cloud formation and establishing the first link between aerosol composition and cloud formation. Even more importantly, they establish a new and crucial link between life on Earth and cloud formation and open new perspectives on the role of life (in particular microbial life) in the Earth's system and climate.

Another direction focusing on the transformation of organic compounds in aerosols led to the discovery of several classes of natural catalysts for such reactions, which were not previously known: amino acids and different classes of inorganic salts. Some salts, in particular, were not previously known as catalysts, although these processes have been studied for two centuries in organic chemistry. Two patents were thus filed during OMAA.

All these catalysts are efficient in atmospheric aerosols and would lead to important transformations, supported by atmospheric observations, such as:
- the formation of light-absorbing products in otherwise non-absorbing aerosols, modifying their role on climate;
- the formation of secondary organic aerosols from some organic gases (glyoxal);
- the depletion of these gases from the atmosphere, affecting ozone chemistry.

The main objectives of OMAA have thus been achieved and the results have opened important new directions of research for atmospheric sciences, and relevant for other disciplines such as organic chemistry, geochemistry, and climate science.

In total, OMAA has resulted until now in 10 publications (including the 2 patents), and 16 public presentations (11 of which at international conferences). The research topic studied have also attracted about EUR 500 000 of funding from Swedish institutions to pursues these investigations.