Comment & Debate
Alan Robock. “20 reasons why geoengineering may be a bad idea”. Bulletin of the Atomic Scientist. 2008: 4. Effects on plants. Sunlight scatters as it passes through stratospheric aerosols, reducing direct solar radiation and increasing diffuse radiation, with important biological consequences. Some studies, including one that measured this effect in trees following the Mount Pinatubo eruption, suggest that diffuse radiation allows plant canopies to photosynthesize more efficiently, thus increasing their capacity as a carbon sink.9 At the same time, inserting aerosols or reflective disks into the atmosphere would reduce the total sunlight to reach Earth’s surface. Scientists need to assess the impacts on crops and natural vegetation of reductions in total, diffuse, and direct solar radiation.