Spatial Patterns of Climate Impact from Anthropogenic Aerosols in the Early Instrumental Period

Abstract:

Anthropogenic aerosols have emerged as an important player affecting global and regional climate with significant impacts on both the energy and water cycles. The early instrumental period (1850-1950), characterized by the increase of North American and especially European aerosol emissions concurrently with negligible Asian emissions and relatively low carbon dioxide concentrations, is an interesting case study to isolate the aerosol impact.
Observations and historical experiments with state-of-the-art CMIP5 models are used to identify regions affected by aerosols. We compare the spatial and temporal patterns of climate variables such as surface temperature and precipitation with those of aerosol emissions and aerosol optical depth (AOD). In addition to regions showing the expected relationship between increasing sulfate emissions and decreasing surface temperatures, we see regions and decades with a more complex temperature response, and the first third of the twentieth century stands out as an especially interesting period. The contribution of atmospheric circulation changes is also pointed out.