The main findings of G1 include:
- Geoengineering can return high temperatures under global warming to preindustrial levels, with some regional variation.
- Geoengineering can prevent Arctic sea ice loss under global warming.
- Precipitation in the tropics declines under geoengineering due to reduced atmospheric convection.
- Plant growth increases in a geoengineered world as a result of the CO2 fertilization effect combined with reduced heat stress.
The authors conclude, "For most of the results presented in this study, changes in G1 [geoengineering simulation] relative to piControl [preindustrial control run] are substantially smaller than changes in abrupt4xCO2 [global warming simulation] relative to piControl" (p. 11). While these scenarios are greatly simplified and highly idealized, comparison of modeling results provides first-order quantitative evidence of how a geoengineered world would look relative to a world experiencing significant climate change without SRM.