Northern-high-latitude permafrost and terrestrial carbon response to two solar geoengineering scenarios

G6solar and G6sulfur can slow the northern-high-latitude permafrost degradation but cannot restore the permafrost states from ssp585 to those under ssp245. G6solar and G6sulfur tend to produce a deeper active layer than ssp245 and expose more thawed soil organic carbon (SOC) due to robust residual high-latitude warming, especially over northern Eurasia. G6solar and G6sulfur preserve more SOC of 4.6 +/- 4.6 and 3.4 +/- 4.8 Pg C (coupled ESM simulations) or 16.4 +/- 4.7 and 12.3 +/- 7.9 Pg C (offline land surface model simulations), respectively, than ssp585 in the northern near-surface permafrost region.

The turnover times of SOC decline slower under G6solar and G6sulfur than ssp585 but faster than ssp245. The permafrost carbon-climate feedback is expected to be weaker under solar geoengineering.