Solar Radiation Modification is projected to increase land carbon storage and to protect the Amazon rainforest

Abstract Solar radiation modification (SRM) aims to artificially cool the Earth, counteracting warming from anthropogenic greenhouse gases by increasing the reflection of incoming sunlight. One SRM strategy is stratospheric aerosol injection (SAI), which mimics explosive volcanoes by injecting aerosols into the stratosphere. There are concerns that SAI could suppress vegetation productivity by reducing the amount of sunlight reaching the Earth’s surface and by shifting rainfall patterns. Here we examine results from five Earth System Models that use SAI to reduce the global mean temperature from that of a high emissions world (SSP585), to that of a more moderate global warming scenario (SSP245). Compared to SSP245, the SAI simulations project higher global NPP values (+15.6%) and higher land carbon storage (+5.9%), primarily because of increased CO2 fertilization. The effects of SAI are most obvious in Amazonia where notable increases in NPP (+13.8%) and land carbon storage (+8.6%) are projected compared to SSP245, as well as compared to SSP585 (+10.8% and +7.1% respectively). Our results therefore suggest that SAI could provide some protection against the risk of climate change induced Amazon forest dieback, and may in fact be a very effective method of atmospheric carbon sequestration.