Researchers from the Aerosol Physics Research Group at UEF participated in a study that investigated the formation of aerosols from forest emissions, their climate effects and the performance of atmospheric models in describing these.
The study, published in Nature Communications, revealed variability between models in describing aerosols and their climate effects, and deviation of model predictions from atmospheric observations.
The research focused on climate feedback driven by the formation of aerosols from forest emissions. Plants emit gaseous organic compounds which can form aerosols in the atmosphere upon oxidation. The emissions of these gases from forest tend to increase with temperature, which may lead to higher aerosol concentrations. This, in turn, may increase the amount of condensation nuclei for cloud droplets and therefore affect cloud properties. As climate is warming, these aerosols formed from forest emissions are expected to drive a climate feedback that slows down the warming, but the strength of the effect is still uncertain. With decreasing anthropogenic emissions, the role of aerosols from natural sources, such as forests, is expected to increase in the future.
The new study investigated the chain of processes from forest emissions to changes in cloud properties in two forest environments: boreal forest in Finland and Amazon tropical rainforest. The strength of the climate feedback has been previously estimated from observations in boreal forest, while for the tropical forest in Amazon the observational evidence for the feedback was now presented for the first time. Global atmospheric models play a key role in predicting future climate. Therefore, the performance of four global atmospheric models in simulating the climate effects of aerosols formed from forest emissions were analysed in these two environments.
The researchers investigated different parts of the process chain from forest emissions through aerosols to climate effects and compared the predictions of different models with each other and with atmospheric observations. The study used both aerosol observations from two measurement stations and satellite-based measurements of cloud properties. The two measurement stations selected for the study provide long-term data on atmospheric aerosols. A comparison revealed differences in the capability of the models to predict different parts of the process chain, and model predictions also showed deviations from observations. The model predictions differed from observations especially for the tropical forest environment. The differences in model performance between the two environments indicate the importance of obtaining long-term observations from different environments for the evaluation of atmospheric models. The variability between the models, on the other hand, highlights the need for further development of atmospheric models in simulating the formation of aerosols from forest emissions and the interaction between aerosols and clouds.
Researchers from the Aerosol Physic Research Group at UEF participated in the study, which was led by Stockholm University. The research is part of the Atmosphere and Climate Competence Center funded by the Research Council of Finland, and the EU-funded project FORCeS.
For further information, please contact:
Research Director Taina Yli-Juuti, tel. +358 46 921 4429, taina.yli-juuti@uef.fi
Research article:
Blichner, S.M., Yli-Juuti, T., Mielonen, T. et al. Process-evaluation of forest aerosol-cloud-climate feedback shows clear evidence from observations and large uncertainty in models. Nat Commun 15, 969 (2024). https://doi.org/10.1038/s41467-024-45001-y
