Small sulfate particles of diameters 0.4 µm or less from anthropogenic sources could have had a cooling effect on the climate in the 1970s, by triggering cloud formation and reflection radiation.
Global warming and climate change are one of the most pressing issues of this century. It is well known that carbon dioxide is the most common greenhouse gas, but what is less known is that a few anthropogenic aerosols retard the effects of greenhouse gases. One such chemical is sulfate, which is more infamous for its role in acid rain.
A team of scientists led by Professor Yoshinori Iizuka at the Institute of Low Temperature Science, Hokkaido University, has succeeded in reconstructing the particle sizes of sulfates deposited in Greenland ice cores, allowing for an accurate determination of their effect on global warming. Their findings have been published in the Journal of Geophysical Research: Atmospheres. The research team included Ryu Uemura, Nagoya University; Naga Oshima, Japan Meteorological Agency; and Shohei Hattori, Nanjing University.
Until the introduction of regulation in the 1970s, the primary anthropogenic source of sulfate aerosols was sulfur dioxide from fossil fuels. While sulfur dioxide is still emitted due to various anthropogenic activities, the quantity is much smaller today.
Read more at Hokkaido University
Image: Processing the ice core used in the study in Greenland, shortly after its collection (Photo: Yoshinori Iizuka).