Interactions between Aerosols and Vegetation: Analysing trends of vapour pressure deficit

Oral Presentation 

The dynamic relationship between the atmosphere and biosphere is a critical study area due to their constant influential effects on each other. Aerosols alter the radiation reaching the surface and hence influence the climate, impacting vegetation, while the biosphere responds to changes in the atmosphere and further influences the climate through its ability to capture and store carbon. This study investigates the particles’ impacts on Vapour Pressure Deficit (VPD), a variable used to determine the atmospheric water demand for plants, as well as its impacts on vegetation growth over Europe and Asia (India and China). Through the utilisation of observational datasets and large ensemble climate models, this study reports a shift from decreasing to substantially increasing trends as a result of the reduction in emissions of anthropogenic aerosols in Europe during the mid 1970s. In Asia, where the emissions of aerosols were not reduced at this time, a positive trend of VPD is observed also in this region during the period of study (1950- 2005). The study further investigates the relationship between VPD and Normalised Difference Vegetation Index (NDVI) between 1982 and 2005. NDVI is a variable that measures the vegetation conditions, and the results show an increase over large areas of Europe and Asia, indicating a vegetation greening trend. This clearly suggests that the increase in VPD may not have had the substantial impact on vegetation as initially anticipated, and that the NDVI trends may be explained by other dynamics. The study suggests that these dynamics include increased radiation and nutrient deposition, afforestation projects, or a delay in vegetation response.