It's come up a few times, I can't remember where. But it's really just evidence that people are thinking about doing geoengineering in the future, and are asking questions about how it might work. There's nothing in it that suggests they were doing it in the past (other than CO2 reduction). It's obviously something that NEEDS regulation.
The only actual SRM test they mention is Izreal 2009, which David Keith described as spraying some stuff out of a helicopter. It was not really a geoengineering test, as it did not even affect the local weather, more a test of how much various particles block sunlight.
Although so far it has received little or no attention, the journal Russian Meteorology and Hydrology recently published a new kind of geoengineering study whose lead author is the journal's editor, the prominent Russian scientist Yuri A. Izrael. Known for his opposition to the Kyoto Protocol, his skepticism of human-caused global warming, and his enthusiasm for geoengineering, Izrael also happens to be a top scientific adviser to Vladimir Putin. And now, his paper reports on what is probably the very first geoengineering field trial. Izrael and his team of scientists mounted aerosol generators on a helicopter and a car chassis, and proceeded to blast out particles at ground level and at heights of up to 200 meters. Then they attempted to measure just how much sunlight reaching the earth was reduced due to the aerosol plume.This small-scale intervention was effective, the Russian scientists say. And in an accompanying article on geoengineering alternatives, Izrael and colleagues note that "Already in the near future, the technological possibilities of a full scale use of [aerosol-based geoengineering] will be studied."
Results of a field experiment on studying solar radiation passing in the visible wavelength range are described with the model aerosol media created in the surface atmosphere. High-efficiency thermocondensation generators were used for creating model aerosol media. The index of refraction and an average size of the aerosol particles formed are close to those characteristic of the natural stratospheric aerosol. The composition and technical characteristics of the equipment complex used in the experiments to control aerosol optical and microphysical parameters and meteorological conditions of the experiment are considered. The Gaussian model of impurity dispersion in the boundary layer is used for the analysis and interpretation of measurement results. It is found that with a number concentration of aerosol particles of ∼102–103 cm−3 (which corresponds to the aerosol density in the deposited layer of about 1–10 mg/m2 with the layer thickness along the ray path of about 100 m) the solar radiation attenuation with artificial aerosol layers accounts for 1 to 10%. Model estimates are in satisfactory agreement with the measurement results.