*Poster's note: Peer-reviewed, final version of paper * https://esd.copernicus.org/articles/14/55/2023/
*Northern-high-latitude permafrost and terrestrial carbon response to two solar geoengineering scenarios * *Authors* Yangxin Chen, Duoying Ji, Qian Zhang, John C. Moore, Olivier Boucher, Andy Jones, Thibaut Lurton, Michael J. Mills, Ulrike Niemeier, Roland Séférian, and Simone Tilmes *25 January 2023* *Citation*: Chen, Y., Ji, D., Zhang, Q., Moore, J. C., Boucher, O., Jones, A., ... & Tilmes, S. (2023). Northern-high-latitude permafrost and terrestrial carbon response to two solar geoengineering scenarios. *Earth System Dynamics*, *14*(1), 55-79. https://doi.org/10.5194/esd-14-55-2023 *Abstract* The northern-high-latitude permafrost contains almost twice the carbon content of the atmosphere, and it is widely considered to be a non-linear and tipping element in the earth's climate system under global warming. Solar geoengineering is a means of mitigating temperature rise and reduces some of the associated climate impacts by increasing the planetary albedo; the permafrost thaw is expected to be moderated under slower temperature rise. We analyze the permafrost response as simulated by five fully coupled earth system models (ESMs) and one offline land surface model under four future scenarios; two solar geoengineering scenarios (G6solar and G6sulfur) based on the high-emission scenario (ssp585) restore the global temperature from the ssp585 levels to the moderate-mitigation scenario (ssp245) levels via solar dimming and stratospheric aerosol injection. 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. [image: https://esd.copernicus.org/articles/14/55/2023/esd-14-55-2023-f01] <https://esd.copernicus.org/articles/14/55/2023/esd-14-55-2023-f01-web.png> Figure 1The multi-model mean changes in surface-absorbed shortwave radiation (Δ*R**N*; a, b, c, d), near-surface air temperature (Δ*T*as; e, f, g, h), 0.2 m soil temperature (Δ*T*soil_0.2m; i, j, k, l), 2 m soil temperature (Δ*T*soil_2m; m, n, o, p), and precipitation (Δ*P*; q, r, s, t) under G6solar and G6sulfur relative to ssp245 for the period 2080–2099 over the baseline PF50 *%* region. The left two columns show changes in winter (December, January, and February); the right two columns show changes in summer (June, July, and August). The hatched area in each panel indicates where fewer than 80 % of the ESMs (four out of five) agree on the sign of changes. [image: https://esd.copernicus.org/articles/14/55/2023/esd-14-55-2023-f04] <https://esd.copernicus.org/articles/14/55/2023/esd-14-55-2023-f04-web.png> *Figure 4*The multi-model mean changes in terrestrial carbon fluxes and carbon storages over the baseline permafrost region during the period 2015–2099 relative to the baseline period 1995–2014 under ssp245, ssp585, G6solar, and G6sulfur. The left column shows changes in NPP (a), *R*h (b), and NEP (c). The right column shows changes in vegetation (d), soil (e) and terrestrial (f) carbon storages. In each panel, bar charts denote 1 standard deviation from the multi-model mean averaged over the period 2080–2099, and the number above each bar denotes its magnitude. Solid lines and filled solid bars represent the anomaly-forcing CLM5 simulations. Dashed lines and hatched bars represent the ESM simulations. In panel (c), an 11-year running average is applied to an NEP time series to filter its large inter-annual variation. [image: https://esd.copernicus.org/articles/14/55/2023/esd-14-55-2023-f06] <https://esd.copernicus.org/articles/14/55/2023/esd-14-55-2023-f06-web.png> Figure 6The multi-model mean changes in *R*h (left column) and soil carbon storage (right column) averaged for the period 2080–2099 under ssp245, ssp585, G6solar, and G6sulfur relative to the baseline period 1995–2014 over the baseline permafrost region in the anomaly-forcing CLM5 simulations. The middle column shows NEP for the period 2080–2099. The hatched area indicates where the sign of the plotted field is the same for the anomaly-forcing CLM5 simulations and corresponding ESM simulations in terms of multi-model mean. *Source: European Geosciences Union * -- You received this message because you are subscribed to the Google Groups "geoengineering" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. 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