scholarly journals Temperature sensitivity of permafrost carbon release mediated by mineral and microbial properties

2021 ◽  
Vol 7 (32) ◽  
pp. eabe3596
Author(s):  
Shuqi Qin ◽  
Dan Kou ◽  
Chao Mao ◽  
Yongliang Chen ◽  
Leiyi Chen ◽  
...  
Keyword(s):  
Temperature Sensitivity ◽  
Temperature Response ◽  
Climate Feedback ◽  
The Tibetan Plateau ◽  
Dual Roles ◽  
Microbial Properties ◽  
C Dynamics ◽  
Mineral Associations ◽  
Carbon Release ◽  
Permafrost Soils

Temperature sensitivity (Q10) of permafrost carbon (C) release upon thaw is a vital parameter for projecting permafrost C dynamics under climate warming. However, it remains unclear how mineral protection interacts with microbial properties and intrinsic recalcitrance to affect permafrost C fate. Here, we sampled permafrost soils across a 1000-km transect on the Tibetan Plateau and conducted two laboratory incubations over 400- and 28-day durations to explore patterns and drivers of permafrost C release and its temperature response after thaw. We find that mineral protection and microbial properties are two types of crucial predictors of permafrost C dynamics upon thaw. Both high C release and Q10 are associated with weak organo-mineral associations but high microbial abundances and activities, whereas high microbial diversity corresponds to low Q10. The attenuating effects of mineral protection and the dual roles of microbial properties would make the permafrost C-climate feedback more complex than previously thought.

scholarly journals Temperature sensitivity of SOM decomposition governed by aggregate protection and microbial communities

2019 ◽  
Vol 5 (7) ◽  
pp. eaau1218 ◽  
Author(s):  
Shuqi Qin ◽  
Leiyi Chen ◽  
Kai Fang ◽  
Qiwen Zhang ◽  
Jun Wang ◽  
...  
Keyword(s):  
Microbial Communities ◽  
Temperature Sensitivity ◽  
Temperature Response ◽  
Climate Feedback ◽  
Soil C ◽  
Active Pool ◽  
Pool Model ◽  
Som Decomposition

Temperature sensitivity (Q10) of soil organic matter (SOM) decomposition is a crucial parameter for predicting the fate of soil carbon (C) under global warming. However, our understanding of its regulatory mechanisms remains inadequate, which constrains its accurate parameterization in Earth system models and induces large uncertainties in predicting terrestrial C-climate feedback. Here, we conducted a long-term laboratory incubation combined with a two-pool model and manipulative experiments to examine potential mechanisms underlying the depth-associated Q10 variations in active and slow soil C pools. We found that lower microbial abundance and stronger aggregate protection were coexisting mechanisms underlying the lower Q10 in the subsoil. Of them, microbial communities were the main determinant of Q10 in the active pool, whereas aggregate protection exerted more important control in the slow pool. These results highlight the crucial role of soil C stabilization mechanisms in regulating temperature response of SOM decomposition, potentially attenuating the terrestrial C-climate feedback.

scholarly journals Convergence in the temperature response of leaf respiration across biomes and plant functional types

2016 ◽  
Vol 113 (14) ◽  
pp. 3832-3837 ◽  
Author(s):  
Mary A. Heskel ◽  
Odhran S. O’Sullivan ◽  
Peter B. Reich ◽  
Mark G. Tjoelker ◽  
Lasantha K. Weerasinghe ◽  
...  
Keyword(s):  
Temperature Sensitivity ◽  
Land Surface ◽  
Response Curve ◽  
Fossil Fuels ◽  
Temperature Response ◽  
Plant Functional Types ◽  
Leaf Respiration ◽  
Functional Types ◽  
Carbon Release ◽  
Plant Respiration

Plant respiration constitutes a massive carbon flux to the atmosphere, and a major control on the evolution of the global carbon cycle. It therefore has the potential to modulate levels of climate change due to the human burning of fossil fuels. Neither current physiological nor terrestrial biosphere models adequately describe its short-term temperature response, and even minor differences in the shape of the response curve can significantly impact estimates of ecosystem carbon release and/or storage. Given this, it is critical to establish whether there are predictable patterns in the shape of the respiration–temperature response curve, and thus in the intrinsic temperature sensitivity of respiration across the globe. Analyzing measurements in a comprehensive database for 231 species spanning 7 biomes, we demonstrate that temperature-dependent increases in leaf respiration do not follow a commonly used exponential function. Instead, we find a decelerating function as leaves warm, reflecting a declining sensitivity to higher temperatures that is remarkably uniform across all biomes and plant functional types. Such convergence in the temperature sensitivity of leaf respiration suggests that there are universally applicable controls on the temperature response of plant energy metabolism, such that a single new function can predict the temperature dependence of leaf respiration for global vegetation. This simple function enables straightforward description of plant respiration in the land-surface components of coupled earth system models. Our cross-biome analyses shows significant implications for such fluxes in cold climates, generally projecting lower values compared with previous estimates.

scholarly journals Regulation of priming effect by soil organic matter stability over a broad geographic scale

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Leiyi Chen ◽  
Li Liu ◽  
Shuqi Qin ◽  
Guibiao Yang ◽  
Kai Fang ◽  
...  
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Priming Effect ◽  
Basal Respiration ◽  
Soil Conditions ◽  
The Tibetan Plateau ◽  
Geographic Scale ◽  
Soil C ◽  
Chemical Structures ◽  
C Dynamics

Abstract The modification of soil organic matter (SOM) decomposition by plant carbon (C) input (priming effect) represents a critical biogeochemical process that controls soil C dynamics. However, the patterns and drivers of the priming effect remain hidden, especially over broad geographic scales under various climate and soil conditions. By combining systematic field and laboratory analyses based on multiple analytical and statistical approaches, we explore the determinants of priming intensity along a 2200 km grassland transect on the Tibetan Plateau. Our results show that SOM stability characterized by chemical recalcitrance and physico-chemical protection explains more variance in the priming effect than plant, soil and microbial properties. High priming intensity (up to 137% of basal respiration) is associated with complex SOM chemical structures and low mineral-organic associations. The dependence of priming effect on SOM stabilization mechanisms should be considered in Earth System Models to accurately predict soil C dynamics under changing environments.

scholarly journals Assessing Snow Phenology over the Large Part of Eurasia Using Satellite Observations from 2000 to 2016

2020 ◽  
Vol 12 (12) ◽  
pp. 2060
Author(s):  
Yanhua Sun ◽  
Tingjun Zhang ◽  
Yijing Liu ◽  
Wenyu Zhao ◽  
Xiaodong Huang
Keyword(s):  
Snow Cover ◽  
Southern China ◽  
Climate Feedback ◽  
Onset Date ◽  
West Siberian Plain ◽  
Positive Trend ◽  
The Tibetan Plateau ◽  
Ecological Processes ◽  
Mountain Areas ◽  
Snow Cover Extent

Snow plays an important role in meteorological, hydrological and ecological processes, and snow phenology variation is critical for improved understanding of climate feedback on snow cover. The main purpose of the study is to explore spatial-temporal changes and variabilities of the extent, timing and duration, as well as phenology of seasonal snow cover across the large part of Eurasia from 2000 through 2016 using a Moderate Resolution Imaging Spectroradiometer (MODIS) cloud-free snow product produced in this study. The results indicate that there are no significant positive or negative interannual trends of snow cover extent (SCE) from 2000 to 2016, but there are large seasonal differences. SCE shows a significant negative trend in spring (p = 0.01) and a positive trend in winter. The stable snow cover areas accounting for 78.8% of the large part of Eurasia, are mainly located north of latitude 45° N and in the mountainous areas. In this stable area, the number of snow-covered days is significantly increasing (p < 0.05) in 6.4% of the region and decreasing in 9.1% of the region, with the decreasing areas being mainly located in high altitude mountain areas and the increasing area occurring mainly in the ephemeral snow cover areas of northeastern and southern China. In central Siberia, Pamir and the Tibetan Plateau, the snow onset date tends to be delayed while the end date is becoming earlier from 2000 to 2016. While in the relatively low altitude plain areas, such as the West Siberian Plain and the Eastern European Plain region, the snow onset date is tending to advance, the end date tends to be delayed, but the increase is not significant.

Why Is There an Early Spring Cooling Shift Downstream of the Tibetan Plateau?

2005 ◽  
Vol 18 (22) ◽  
pp. 4660-4668 ◽  
Author(s):  
Jian Li ◽  
Rucong Yu ◽  
Tianjun Zhou ◽  
Bin Wang
Keyword(s):  
Tibetan Plateau ◽  
North Africa ◽  
North Atlantic ◽  
Radiative Forcing ◽  
Temperature Shift ◽  
Early Spring ◽  
Climate Feedback ◽  
The Tibetan Plateau ◽  
The North ◽  
The North Atlantic

Abstract The temperature shift over the eastern flank of the Tibetan Plateau is examined using the last 50 yr of Chinese surface station observations. It was found that a strong cooling shift occurs in early spring (March and April) and late summer (July, August, and September) in contrast to the warming shift in other seasons. The cause of the March–April (MA) cooling is investigated in this study. The MA cooling shift on the lee side of the Tibetan Plateau is found to be not a local phenomenon, but rather it is associated with an eastward extension of a cooling signal originating from North Africa that is related to the North Atlantic Oscillation (NAO) in the previous winter. The midtropospheric westerlies over the North Atlantic and North Africa tend to intensify during positive NAO phases. The enhanced westerlies, after passing over the Tibetan Plateau, result in strengthened ascending motion against the lee side of the plateau, which favors the formation of midlevel stratiform clouds. The increased amount of stratus clouds induces a negative net cloud–radiative forcing, which thereby cools the surface air and triggers a positive cloud–temperature feedback. In this way, the cooling signal from the upstream could “jump” over the Tibetan Plateau and leave a footprint on its lee side. The continental stratiform cloud–climate feedback plays a significant role in the amplification of the cooling shift downstream of the Tibetan Plateau.

scholarly journals Multiannual Ocean–Atmosphere Adjustments to Radiative Forcing

2016 ◽  
Vol 29 (15) ◽  
pp. 5643-5659 ◽  
Author(s):  
Maria A. A. Rugenstein ◽  
Jonathan M. Gregory ◽  
Nathalie Schaller ◽  
Jan Sedláček ◽  
Reto Knutti
Keyword(s):  
Time Scales ◽  
Radiative Forcing ◽  
Lower Boundary ◽  
Temperature Response ◽  
Fast Response ◽  
Meridional Overturning Circulation ◽  
Climate Feedback ◽  
Characteristic Time Scale ◽  
Lower Boundary Condition ◽  
Global Mean Temperature

Abstract In radiative forcing and climate feedback frameworks, the initial stratospheric and tropospheric adjustments to a forcing agent can be treated as part of the forcing and not as a feedback, as long as the average global surface temperature response is negligible. Here, a very large initial condition ensemble of the Community Earth System Model is used to analyze how the ocean shapes the fast response to radiative forcing. It is shown that not only the stratosphere and troposphere but also the ocean adjusts. This oceanic adjustment includes meridional ocean heat transport convergence anomalies, which are locally as large as the surface heat flux anomalies, and an increase of the Atlantic meridional overturning circulation. These oceanic adjustments set the lower boundary condition for the atmospheric response of the first few years, in particular, the shortwave cloud radiative effect. This cloud adjustment causes a nonlinear relationship between global energy imbalance and temperature. It proceeds with a characteristic time scale of a few years in response to the forcing rather than scaling nonlinearly with global mean temperature anomaly. It is proposed that even very short time scales are treated as a fully coupled problem and encourage other modeling groups to investigate whether our description also suits their models’ behavior. A definition of the forcing term (“virtual forcing”) including oceanic adjustment processes is introduced and serves as an interpretive idea for longer time scales.

Study on Engineering-Material Properties and Influences of Incubated Temperatures on Soil Carbon Decomposition

2013 ◽  
Vol 675 ◽  
pp. 280-283
Author(s):  
Qiu Xiang Tian ◽  
Hong Bo He ◽  
Xu Dong Zhang
Keyword(s):  
Soil Carbon ◽  
Temperature Sensitivity ◽  
Carbon Materials ◽  
Thermal Adaptation ◽  
Soil Environment ◽  
Carbon Decomposition ◽  
Environment Temperature ◽  
Carbon Release ◽  
Higher Temperature ◽  
Lower Temperature

The mineralization of soil carbon materials potentially alters carbon release from soil and the atmospheric carbon concentration in engineering. Despite this central role in the decomposition of soil carbon materials, few studies have been conducted on how climate warming affects this carbon emissions and then response in return back. To study this, five soils were incubated in 5, 15, 25 °C for one month. Soil shifted to warming condition slowed down the increasing rate of decomposition causing by higher temperature. Furthermore, raising the soil environment temperature to 25 °C weakened the temperature sensitivity of the decomposition of these carbon materials, and the temperature sensitivity enhanced at lower temperature. This “thermal adaptation” of carbon material would potentially slow down carbon loss which accelerated by climate change technically.

scholarly journals A simplified, data-constrained approach to estimate the permafrost carbon–climate feedback

2015 ◽  
Vol 373 (2054) ◽  
pp. 20140423 ◽  
Author(s):  
C. D. Koven ◽  
E. A. G. Schuur ◽  
C. Schädel ◽  
T. J. Bohn ◽  
E. J. Burke ◽  
...  
Keyword(s):  
Climate Change ◽  
Large Scale ◽  
Climate Feedback ◽  
Soil Horizon ◽  
Future Climate Change ◽  
Thermal Dynamics ◽  
Soil C ◽  
Warming Scenario ◽  
C Stocks ◽  
Permafrost Soils

We present an approach to estimate the feedback from large-scale thawing of permafrost soils using a simplified, data-constrained model that combines three elements: soil carbon (C) maps and profiles to identify the distribution and type of C in permafrost soils; incubation experiments to quantify the rates of C lost after thaw; and models of soil thermal dynamics in response to climate warming. We call the approach the Permafrost Carbon Network Incubation–Panarctic Thermal scaling approach (PInc-PanTher). The approach assumes that C stocks do not decompose at all when frozen, but once thawed follow set decomposition trajectories as a function of soil temperature. The trajectories are determined according to a three-pool decomposition model fitted to incubation data using parameters specific to soil horizon types. We calculate litterfall C inputs required to maintain steady-state C balance for the current climate, and hold those inputs constant. Soil temperatures are taken from the soil thermal modules of ecosystem model simulations forced by a common set of future climate change anomalies under two warming scenarios over the period 2010 to 2100. Under a medium warming scenario (RCP4.5), the approach projects permafrost soil C losses of 12.2–33.4 Pg C; under a high warming scenario (RCP8.5), the approach projects C losses of 27.9–112.6 Pg C. Projected C losses are roughly linearly proportional to global temperature changes across the two scenarios. These results indicate a global sensitivity of frozen soil C to climate change ( γ sensitivity) of −14 to −19 Pg C °C −1 on a 100 year time scale. For CH 4 emissions, our approach assumes a fixed saturated area and that increases in CH 4 emissions are related to increased heterotrophic respiration in anoxic soil, yielding CH 4 emission increases of 7% and 35% for the RCP4.5 and RCP8.5 scenarios, respectively, which add an additional greenhouse gas forcing of approximately 10–18%. The simplified approach presented here neglects many important processes that may amplify or mitigate C release from permafrost soils, but serves as a data-constrained estimate on the forced, large-scale permafrost C response to warming.

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