Pinatubo, Diffuse Light, and the Carbon Cycle

Similar to clouds, volcanic eruptions increase the proportion of diffuse light reaching Earth9s surface. As Farquhar and Roderick show in their Perspective, this change in the geometry (rather than intensity) of light can have a profound influence on photosynthesis and the carbon cycle. They highlight the research article by Gu et al., who have measured changes in net COexchange following the eruption of Mt. Pinatubo in 1991. Volcanoes, pollution, and greenhouse gases may all increase diffuse light, with important consequences for Earth9s carbon cycle and climate.