Climatological effects of atmospheric particulate pollution

Abstract

THE large amount of dust thrown into the atmosphere by volcanoes has long been recognised as an important factor in initiating climatic change that generally leads to cooler surface temperatures^1–4. Another source of atmospheric dust is man's agricultural and industrial activity. It has been suggested that this anthropogenic source is a cause of cooling in a manner similar to that of volcanoes^5,6. The primary mechanism thought to be responsible for cooling in both these situations is the backscatter to space of a portion of the incoming solar radiation. This reduction in heat input to the planet would cool its surface. Idso^7–10 has argued for another effect of atmospheric dust—warming due to ‘thermal blanketing’. This mechanism would absorb some of the Earth's thermal radiation that would otherwise escape to space and then reradiate a portion of this radiation back to the surface, hence a rise in surface temperature with increasing atmospheric dust would be expected. We have completed an experiment recently in which the relative magnitudes of the solar and thermal radiation interactions with atmospheric dust were compared¹¹. The results reported there indicate that there is a general climatological superiority for the thermal radiation interaction, predicting a net warming trend with increasing atmospheric dust for all but the most extreme cases of dust-loading of the atmosphere.