We estimated the distribution of CH₄ emissions and sinks from wetlands (including freshwater and coastal wetlands) and nonwetland (including wet and dry soils) with a newly developed vertically resolved soil CH₄ model, integrated into a global land surface model (ISAM). We calibrated and tested this integrated model with CH₄ observations at test sites in the Contiguous United States (CONUS). ISAM is applied across the CONUS to estimate CH₄ emissions and sinks given both recent past observed climate and wetland extent, and future climate and wetland extent driven by two scenarios, RCP4.5 and RCP8.5. Estimated net CH₄ emissions for the 2000s are 13.8 TgCH₄ yr⁻¹, mostly from wetland soils. Estimated net emissions under RCP4.5 and RCP8.5 are 30% and 64% higher, respectively, in the 2090s than in the 2000s due to (1) higher temperature and seasonal wetland extent (driven by higher precipitation in the climate scenarios), which increase modeled methanogenic activity more than methanotrophic activity in soils and (2) altered transport in the soil column and exchange with the atmosphere by modeled transport processes (diffusion, ebullition, and aerenchyma transport). Nonwetland soils emit CH₄ (1.4 TgCH₄ yr⁻¹) in some areas and take up CH₄ (−2.9 TgCH₄ yr⁻¹) in other areas, resulting in a net estimated sink for the 2000s; the net nonwetland soil sink increases by 15% and 46% by the 2090s under RCP4.5 and RCP8.5, respectively, mainly due to drier soil conditions, which enhances methanotrophic activity and oxidation of CH₄ diffused into soil from a future atmosphere with higher CH₄ concentration.

中文翻译：

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使用陆地表面模型调查整个美国的湿地和非湿地甲烷排放量

我们使用新开发的垂直分解土壤CH ₄模型估算了湿地（包括淡水和沿海湿地）和非湿地（包括湿地和干土）和湿地（包括湿地和旱地）的CH ₄排放和汇的分布，并将其集成到全球陆地表面模型（ISAM）中。我们在美国本土（CONUS）的测试地点使用CH ₄观测值对这一集成模型进行了校准和测试。鉴于最近的过去观测到的气候和湿地范围以及由RCP4.5和RCP8.5两种情景驱动的未来气候和湿地范围，在整个CONUS上应用ISAM来估算CH ₄排放和汇。2000年代估计的CH ₄净排放量为13.8 TgCH ₄  yr ^-1，主要来自湿地土壤。在2090年代，RCP4.5和RCP8.5下的估计净排放量分别比2000年代高30％和64％，这是由于（1）温度和季节性湿地范围增加（在气候情景中降水增加所致），在土壤中，模拟甲烷化活动比甲烷营养活动增加的更多，并且（2）通过模拟运输过程（扩散，沸腾和通气组织运输）改变​​了土壤柱中的运输和与大气的交换。非湿地土壤在某些区域排放CH ₄（1.4 TgCH ₄  yr ^-1），并吸收CH ₄（-2.9 TgCH ₄  yr ^-1））在其他地区，导致2000年代的估计净下降；到2090年代，在RCP4.5和RCP8.5下，非湿地土壤净吸收量分别增加了15％和46％，这主要是由于土壤条件较干燥，这增强了甲烷营养作用，并增加了从未来大气中扩散到土壤中的CH ₄氧化CH ₄浓度较高。