# Biomass Refined: 99% of Organic Carbon in Soils
## 3 Results and Discussion
### Total Global Soil SOC Refined
#### 3.5.2 Permafrost  
Permafrost, occupying 11-15% of land area, is one of Earth's major SOC stores and carbon loss contributors. It is both remarkably old (supposedly in places over 2.5 million years old) and deep with areas of continuous permafrost often >100 m thick and the deepest in Siberia extending to 1650 m depth ([[https://nsidc.org/learn/parts-cryosphere/frozen-ground-permafrost/science-frozen-ground](https://nsidc.org/learn/parts-cryosphere/frozen-ground-permafrost/science-frozen-ground)]([https://nsidc.org/learn/parts-cryosphere/frozen-ground-permafrost/science-frozen-ground](https://nsidc.org/learn/parts-cryosphere/frozen-ground-permafrost/science-frozen-ground)), accessed on 11 November 2024). Non-terrestrial, sub-oceanic stores are not included. It is treated in some detail already, also in [64]; _\"3.2.1 Biotic Boreal Permafrosts Reconsidered but Not Reconciled\"_. It is not intended to repeat all the information provided therein, rather just a brief updated summary herein. Ref. [49] divided Permafrost carbon thusly:  
1. Near-surface Permafrost soils (0-3 m)--1035 Gt SOC;
2. Yedoma deposits of Siberia and Alaska (>3 m of 327-466)--median 397 Gt C;
3. Arctic river deltas (at soil depth > 3 and up to 60 m deep)--96 Gt C;
4. Qinghai-Xizang (Tibet) Plateau and northern China (to full depth?) --36 Gt C;
5. Deep deposits outside the Yedoma region (of 350-465 to >3 m?) --median 408 Gt C;
6. [Subsea permafrost, \(\sim\)560 Gt C, herein ignored as not in current terrestrial C stocks.] For some reason, they gave a median only for categories 1 to 3 of 1530 Gt C, whereas for all Permafrost to depth, their data yield (1035 + 397 + \(\sim\)96 + \(\sim\)36 + 408 =) -1972 Gt SOC. Surprisingly, an omitted citation is [22], also indicating up to 2000 Gt C. But, in brief, rather than \(\sim\)1972 or \(\sim\)2000 Gt SOC as just shown, the \"_official_\" IPCC and GCB data (in Table 1 in Introduction) have between 1200-1700 Gt SOC (median: \(\sim\)1450 Gt SOC). Yet, it was unclear whether or not they included Peat. As noted, although [60] implied about 200 Gt C in Permafrost peat, ref. [18] claimed \(\sim\)300 Gt in the boreal region, whereas [113] had Northern peatland store of 415 \(\pm\) 147 Gt C, of which just 185 \(\pm\) 66 Gt C is in Permafrost-affected peatlands. Thus, the most conservative Permafrost value would be about (1450 \(-\) 300 =) 1150 Gt SOC that is about the same as the [PERSON] et al. estimation, less Peat, to \(>\)3 m depth. However, ref. [60] have higher Permafrost figure to greater depth (3-25 m!) of 1672 Gt, of which 1466 Gt was Permafrost proper (i.e., implying just \(\sim\)206 Gt Peat?). A baseline Permafrost mineral soil may reasonably be around \(\sim\)1500-2000 Gt SOC. Yet, the earlier baseline chosen by [22] was of 1300 Gt SOC for which _\"Northern circumpolar permafrost soils contain more than a third of the global soil organic carbon pool (SOC)\"_. Their study combined topographic models with (full?) soil profile data and a topographic analysis to evaluate the quantity of permafrost SOC deposits, finding an approximate >200% uncertainty that may also pertain to a circumpolar scale. For perennially frozen soil in the upper 3 m of circumpolar permafrost terrain, from an initial overall estimate of 822 Gt C, their uncertainty was up to \(>\)200% (or \(\times\)3 times) the prior estimates of SOC mass. They said: \"_SOC mass stored in perennially frozen hill toe deposits alone vary from few percents to more than double of current SOC estimates_\". They indicate mean values of \(\sim\)550 and \(\sim\)720 Gt C for the linear and sigmoidal profile geometries, respectively, with a maximal uncertainty of \(>\)2000 Gt C they said was like estimates of _\"global SOC mass_\" in 0-3 m depths amounting to 2000-3000 Gt SOC. Importantly, their study somewhat validates the rationale to double soil samples for both depth and terrain. Moreover, their distinction between linear and sigmoid models (figures 3f,g in ref.