Enhanced Australian carbon sink despite increased wildfire during the 21st century

Amazonian peatlands store a large amount of soil organic carbon (SOC), and its fate under a future changing climate is unknown. Here, we use a process-based peatland biogeochemistry model to quantify the carbon accumulation for peatland and nonpeatland ecosystems in the Pastaza-Marañon foreland basin (PMFB) in the Peruvian Amazon from 12,000 y before present to AD 2100. Model simulations indicate that warming accelerates peat SOC loss, while increasing precipitation accelerates peat SOC accumulation at millennial time scales. The uncertain parameters and spatial variation of climate are significant sources of uncertainty to modeled peat carbon accumulation. Under warmer and presumably wetter conditions over the 21st century, SOC accumulation rate in the PMFB slows down to 7.9 (4.3–12.2) g⋅C⋅m−2⋅y−1 from the current rate of 16.1 (9.1–23.7) g⋅C⋅m−2⋅y−1, and the region may turn into a carbon source to the atmosphere at −53.3 (−66.8 to −41.2) g⋅C⋅m−2⋅y−1 (negative indicates source), depending on the level of warming. Peatland ecosystems show a higher vulnerability than nonpeatland ecosystems, as indicated by the ratio of their soil carbon density changes (ranging from 3.9 to 5.8). This is primarily due to larger peatlands carbon stocks and more dramatic responses of their aerobic and anaerobic decompositions in comparison with nonpeatland ecosystems under future climate conditions. Peatland and nonpeatland soils in the PMFB may lose up to 0.4 (0.32–0.52) Pg⋅C by AD 2100 with the largest loss from palm swamp. The carbon-dense Amazonian peatland may switch from a current carbon sink into a source in the 21st century.

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Possible decline of the carbon sink in the Mongolian Plateau during the 21st century

Environmental Research Letters ◽

10.1088/1748-9326/4/4/045023 ◽

2009 ◽

Vol 4 (4) ◽

pp. 045023 ◽

Cited By ~ 17

Author(s):

Y Lu ◽

Q Zhuang ◽

G Zhou ◽

A Sirin ◽

J Melillo ◽

...

Keyword(s):

21St Century ◽

Carbon Sink ◽

Mongolian Plateau

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Arable Podzols Are a Substantial Carbon Sink under Current and Future Climates: Evidence from a Long-Term Experiment in the Vladimir Region, Russia

Agronomy ◽

10.3390/agronomy11010090 ◽

2021 ◽

Vol 11 (1) ◽

pp. 90

Author(s):

Igor Ilichev ◽

Vladimir Romanenkov ◽

Sergei Lukin ◽

Vera Pavlova ◽

Stanislav Siptits ◽

...

Keyword(s):

21St Century ◽

Carbon Sink ◽

Soil Layer ◽

Soil Health ◽

Climate Conditions ◽

Central Russia ◽

Vladimir Region ◽

Climatic Scenarios ◽

Long Term Experiment

Soil organic carbon (SOC) is an essential component of soil health and a potential sink for greenhouse gases. SOC dynamics in a long-term field experiment with mineral and organic fertilization on loamy sand podzol in the Vladimir Region, Russia, was traced with the dynamic carbon model RothC from 1968 until the present. During this period, C stock increased by 21%, compared to the initial level, with the application of manure, at an average annual rate of 10 t·ha−1. The model was also used to forecast SOC changes up to 2090 for two contrasting RCP4.5 and RCP8.5 climatic scenarios. Up to 2090, steady growth of SOC stocks is expected in all compared treatments for both climate scenarios. In the scenarios, this growth rate was the highest up to 2040, decreased in the period 2040–2070, and increased again in the period 2070–2090 for RCP4.5. The highest annual gain was 21–27‰ under the RCP4.5 scenario and 16–21‰ under the RCP8.5 scenario in 2020–2040 in a 0–20 cm soil layer. Under the expected climate conditions in the 21st century, the C input will increase 1.3–1.5 times under the RCP4.5 scenario and decrease by 13–20% for the same period under the RCP 8.5 scenario. Modelling demonstrated potentially more favourable conditions for SOC stability in arable podzols than in Retisols in central Russia in the 21st century.

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Microbial decomposition processes and vulnerable arctic soil organic carbon in the 21st century

Biogeosciences ◽

10.5194/bg-15-5621-2018 ◽

2018 ◽

Vol 15 (18) ◽

pp. 5621-5634 ◽

Cited By ~ 2

Author(s):

Junrong Zha ◽

Qianlai Zhuang

Keyword(s):

Soil Carbon ◽

20Th Century ◽

21St Century ◽

Carbon Budget ◽

Carbon Sink ◽

The Arctic ◽

Microbial Decomposition ◽

New Model ◽

Terrestrial Ecosystem Model ◽

Rcp 8.5

Abstract. Various levels of representations of biogeochemical processes in current biogeochemistry models contribute to a large uncertainty in carbon budget quantification. Here, we present an uncertainty analysis with a process-based biogeochemistry model, the Terrestrial Ecosystem Model (TEM), into which detailed microbial mechanisms were incorporated. Ensemble regional simulations with the new model (MIC-TEM) estimated that the carbon budget of the arctic ecosystems is 76.0±114.8 Pg C during the 20th century, i.e., -3.1±61.7 Pg C under the RCP 2.6 scenario and 94.7±46 Pg C under the RCP 8.5 scenario during the 21st century. Positive values indicate the regional carbon sink while negative values are a source to the atmosphere. Compared to the estimates using a simpler soil decomposition algorithm in TEM, the new model estimated that the arctic terrestrial ecosystems stored 12 Pg less carbon over the 20th century, i.e., 19 and 30 Pg C less under the RCP 8.5 and RCP 2.6 scenarios, respectively, during the 21st century. When soil carbon within depths of 30, 100, and 300 cm was considered as initial carbon in the 21st century simulations, the region was estimated to accumulate 65.4, 88.6, and 109.8 Pg C, respectively, under the RCP 8.5 scenario. In contrast, under the RCP 2.6 scenario, the region lost 0.7, 2.2, and 3 Pg C, respectively, to the atmosphere. We conclude that the future regional carbon budget evaluation largely depends on whether or not adequate microbial activities are represented in earth system models and on the sizes of soil carbon considered in model simulations.

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