Dependence of the evolution of carbon dynamics in the northern permafrost region on the trajectory of climate change

We conducted a model-based assessment of changes in permafrost area and carbon storage for simulations driven by RCP4.5 and RCP8.5 projections between 2010 and 2299 for the northern permafrost region. All models simulating carbon represented soil with depth, a critical structural feature needed to represent the permafrost carbon–climate feedback, but that is not a universal feature of all climate models. Between 2010 and 2299, simulations indicated losses of permafrost between 3 and 5 million km2 for the RCP4.5 climate and between 6 and 16 million km2 for the RCP8.5 climate. For the RCP4.5 projection, cumulative change in soil carbon varied between 66-Pg C (1015-g carbon) loss to 70-Pg C gain. For the RCP8.5 projection, losses in soil carbon varied between 74 and 652 Pg C (mean loss, 341 Pg C). For the RCP4.5 projection, gains in vegetation carbon were largely responsible for the overall projected net gains in ecosystem carbon by 2299 (8- to 244-Pg C gains). In contrast, for the RCP8.5 projection, gains in vegetation carbon were not great enough to compensate for the losses of carbon projected by four of the five models; changes in ecosystem carbon ranged from a 641-Pg C loss to a 167-Pg C gain (mean, 208-Pg C loss). The models indicate that substantial net losses of ecosystem carbon would not occur until after 2100. This assessment suggests that effective mitigation efforts during the remainder of this century could attenuate the negative consequences of the permafrost carbon–climate feedback.

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Estimating the Permafrost-Carbon Climate Response in the CMIP5 Climate Models Using a Simplified Approach

Journal of Climate ◽

10.1175/jcli-d-12-00550.1 ◽

2013 ◽

Vol 26 (14) ◽

pp. 4897-4909 ◽

Cited By ~ 44

Author(s):

Eleanor J. Burke ◽

Chris D. Jones ◽

Charles D. Koven

Keyword(s):

Climate Change ◽

Radiative Forcing ◽

Climate Models ◽

Coupled Model ◽

Climate Feedback ◽

Cmip5 Models ◽

Future Climate Change ◽

Permafrost Region ◽

Climate Response ◽

Simplified Approach

Abstract Under climate change, thawing permafrost may cause a release of carbon, which has a positive feedback on the climate. The permafrost-carbon climate response (γPF) is the additional permafrost-carbon made vulnerable to decomposition per degree of global temperature increase. A simple framework was adopted to estimate γPF using the database for phase 5 of the Coupled Model Intercomparison Project (CMIP5). The projected changes in the annual maximum active layer thicknesses (ALTmax) over the twenty-first century were quantified using CMIP5 soil temperatures. These changes were combined with the observed distribution of soil organic carbon and its potential decomposability to give γPF. This estimate of γPF is dependent on the biases in the simulated present-day permafrost. This dependency was reduced by combining a reference estimate of the present-day ALTmax with an estimate of the sensitivity of ALTmax to temperature from the CMIP5 models. In this case, γPF was from −6 to −66 PgC K−1(5th–95th percentile) with a radiative forcing of 0.03–0.29 W m−2 K−1. This range is mainly caused by uncertainties in the amount of soil carbon deeper in the soil profile and whether it thaws over the time scales under consideration. These results suggest that including permafrost-carbon within climate models will lead to an increase in the positive global carbon climate feedback. Under future climate change the northern high-latitude permafrost region is expected to be a small sink of carbon. Adding the permafrost-carbon response is likely to change this region to a source of carbon.

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Solar Radiation Modification Slows Down Permafrost Carbon Loss

10.5194/egusphere-egu2020-1740 ◽

2020 ◽

Author(s):

Yangxin Chen ◽

Duoying Ji

Keyword(s):

Solar Radiation ◽

Soil Carbon ◽

Surface Air Temperature ◽

Carbon Accumulation ◽

Permafrost Region ◽

Permafrost Degradation ◽

Carbon Loss ◽

Microbial Decomposition ◽

Radiation Modification ◽

Lower Temperature

<p>&#160; &#160; Circumpolar permafrost is degrading under anthropogenic global warming, thus the large amount of soil organic carbon in it would be vulnerable to microbial decomposition and further aggravating future warming. However, solar radiation modification (SRM), as a theoretical approach to reducing some of the impacts of anthropogenic climate change, hopefully could mitigate the permafrost degradation and slow down permafrost carbon loss. Here we use two solar geoengineering experiments came up in CMIP6/GeoMIP6 -- G6solar and G6sulfur, to explore changes in circumpolar permafrost carbon under solar radiation modification scenarios. Earth system models' simulations show that under G6 scenarios, annual mean surface air temperature in circumpolar permafrost region is about 5&#8451; lower relative to the high forcing scenario SSP5-8.5 by year 2100, with a growing trend but remains below 0&#8451; from 2015 to 2100, which is close to that in the medium forcing scenario SSP2-4.5. The lower temperature causes lower degradation rate of permafrost area. In SSP5-8.5 scenario, almost all the permafrost thaws by year 2100, but up to half of it remains frozen in SSP2-4.5 and G6 scenarios compared to year 2015. The lower temperature also results in less carbon assimilation in this area, thus the lower vegetation carbon accumulation. By 2100, a maximum soil carbon loss of 18.09 PgC under SSP5-8.5 scenario regarding to different model constructions, while in G6 the soil carbon loss could be reduce to 3.70 PgC, even less than that of 5.29 PgC in SSP2-4.5 scenario.</p>

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Lowland plant migrations into alpine ecosystems amplify soil carbon loss under climate warming

10.1101/2021.07.21.453211 ◽

2021 ◽

Author(s):

Tom W N Walker ◽

Konstantin Gavazov ◽

Thomas Guillaume ◽

Thibault Lambert ◽

Pierre Mariotte ◽

...

Keyword(s):

Soil Carbon ◽

Climate Warming ◽

Root Exudation ◽

Climate Feedback ◽

Alpine Ecosystems ◽

Carbon Loss ◽

Soil Microbial ◽

Herbaceous Communities ◽

Plant Migrations ◽

Positive Climate

Climate warming is releasing carbon from soils around the world1–3, constituting a positive climate feedback. Warming is also causing species to expand their ranges into new ecosystems4–9. Yet, in most ecosystems, whether range expanding species will amplify or buffer expected soil carbon loss is unknown10. Here we used alpine grasslands as a model system to determine whether the establishment of herbaceous lowland plants in alpine ecosystems influences short–term soil carbon storage under warming. We found that warming (< 1 year) led to negligible alpine soil carbon loss, but its effects became significant and 52% ± 31% (mean ± 95% CIs) larger after lowland plants were introduced at low density into the ecosystem. We present evidence that soil carbon loss likely occurred via lowland plants increasing rates of root exudation, soil microbial respiration and CO2 release. Our findings suggest that warming–induced range expansions of herbaceous plants may yield a rapid positive climate feedback in this system, and that plant range expansions among herbaceous communities may be an overlooked mediator of warming effects on carbon dynamics.

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Assessing Wood and Soil Carbon Losses from a Forest-Peat Fire in the Boreo-Nemoral Zone

Forests ◽

10.3390/f12070880 ◽

2021 ◽

Vol 12 (7) ◽

pp. 880

Author(s):

Andrey Sirin ◽

Alexander Maslov ◽

Dmitry Makarov ◽

Yakov Gulbe ◽

Hans Joosten

Keyword(s):

Soil Carbon ◽

Stand Structure ◽

Peat Soil ◽

Burned Area ◽

Tree Biomass ◽

Carbon Loss ◽

Forest Stand Structure ◽

Peat Fire ◽

Peat Fires ◽

Carbon Losses

Forest-peat fires are notable for their difficulty in estimating carbon losses. Combined carbon losses from tree biomass and peat soil were estimated at an 8 ha forest-peat fire in the Moscow region after catastrophic fires in 2010. The loss of tree biomass carbon was assessed by reconstructing forest stand structure using the classification of pre-fire high-resolution satellite imagery and after-fire ground survey of the same forest classes in adjacent areas. Soil carbon loss was assessed by using the root collars of stumps to reconstruct the pre-fire soil surface and interpolating the peat characteristics of adjacent non-burned areas. The mean (median) depth of peat losses across the burned area was 15 ± 8 (14) cm, varying from 13 ± 5 (11) to 20 ± 9 (19). Loss of soil carbon was 9.22 ± 3.75–11.0 ± 4.96 (mean) and 8.0–11.0 kg m−2 (median); values exceeding 100 tC ha−1 have also been found in other studies. The estimated soil carbon loss for the entire burned area, 98 (mean) and 92 (median) tC ha−1, significantly exceeds the carbon loss from live (tree) biomass, which averaged 58.8 tC ha−1. The loss of carbon in the forest-peat fire thus equals the release of nearly 400 (soil) and, including the biomass, almost 650 tCO2 ha−1 into the atmosphere, which illustrates the underestimated impact of boreal forest-peat fires on atmospheric gas concentrations and climate.

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Increased Litter Greatly Enhancing Soil Respiration in Betula platyphylla Forests of Permafrost Region, Northeast China

Forests ◽

10.3390/f12010089 ◽

2021 ◽

Vol 12 (1) ◽

pp. 89

Author(s):

Hong Wei ◽

Xiuling Man

Keyword(s):

Soil Respiration ◽

Carbon Cycle ◽

Soil Carbon ◽

Northeast China ◽

Stand Age ◽

Permafrost Region ◽

Betula Platyphylla ◽

Litter Input ◽

Litter Manipulation ◽

And Control

The change of litter input can affect soil respiration (Rs) by influencing the availability of soil organic carbon and nutrients, regulating soil microenvironments, thus resulting in a profound influence on soil carbon cycle of the forest ecosystem. We conducted an aboveground litterfall manipulation experiment in different-aged Betula platyphylla forests (25-, 40- and 61-year-old) of the permafrost region, located in the northeast of China, during May to October in 2018, with each stand treated with doubling litter (litter addition, DL), litter exclusion (no-litter, NL) and control litter (CK). Our results indicated that Rs decreased under NL treatment compared with CK treatment. The effect size lessened with the increase in the stand age; the greatest reduction was found for young Betula platyphylla forest (24.46% for 25-year-old stand) and tended to stabilize with the growth of forest with the reduction of 15.65% and 15.23% for 40-and 61- year-old stands, respectively. Meanwhile, under DL treatment, Rs increased by 27.38%, 23.83% and 23.58% on 25-, 40- and 61-year-old stands, respectively. Our results also showed that the increase caused by DL treatment was larger than the reduction caused by NL treatment, leading to a priming effect, especially on 40- and 61-year-old stands. The change in litter input was the principal factor affecting the change of Rs under litter manipulation. The soil temperature was also a main factor affecting the contribution rate of litter to Rs of different-aged stands, which had a significant positive exponential correlation with Rs. This suggests that there is a significant relationship between litter and Rs, which consequently influences the soil carbon cycle in Betula platyphylla forests of the permafrost region, Northeast China. Our finding indicated the increased litter enhanced the Rs in Betula platyphylla forest, which may consequently increase the carbon emission in a warming climate in the future. It is of great importance for future forest management in the permafrost region, Northeast China.

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Assessing the Potential for Mobilization of Old Soil Carbon After Permafrost Thaw: A Synthesis of 14 C Measurements From the Northern Permafrost Region

Global Biogeochemical Cycles ◽

10.1029/2020gb006672 ◽

2020 ◽

Vol 34 (9) ◽

Author(s):

Cristian Estop‐Aragonés ◽

David Olefeldt ◽

Benjamin W. Abbott ◽

Jeffrey P. Chanton ◽

Claudia I. Czimczik ◽

...

Keyword(s):

Soil Carbon ◽

Permafrost Region ◽

Permafrost Thaw

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The climatic effects of large injections of atmospheric smoke and dust: A study of climate feedback mechanisms with one- and three-dimensional climate models

Journal of Geophysical Research Atmospheres ◽

10.1029/jd090id07p12937 ◽

1985 ◽

Vol 90 (D7) ◽

pp. 12937 ◽

Cited By ~ 52

Author(s):

R. D. Cess ◽

G. L. Potter ◽

S. J. Ghan ◽

W. L. Gates

Keyword(s):

Climate Models ◽

Three Dimensional ◽

Climate Feedback ◽

Climatic Effects ◽

Feedback Mechanisms

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Joint Occurrence of Daily Temperature and Precipitation Extreme Events over Canada

Journal of Applied Meteorology and Climatology ◽

10.1175/jamc-d-13-0361.1 ◽

2014 ◽

Vol 53 (9) ◽

pp. 2148-2162 ◽

Cited By ~ 18

Author(s):

Bárbara Tencer ◽

Andrew Weaver ◽

Francis Zwiers

Keyword(s):

Climate Models ◽

Regional Climate ◽

Heavy Precipitation ◽

Maximum Temperature ◽

Daily Minimum Temperature ◽

Daily Maximum Temperature ◽

Daily Maximum ◽

Negative Consequences ◽

Temperature And Precipitation ◽

Joint Occurrence

AbstractThe occurrence of individual extremes such as temperature and precipitation extremes can have a great impact on the environment. Agriculture, energy demands, and human health, among other activities, can be affected by extremely high or low temperatures and by extremely dry or wet conditions. The simultaneous or proximate occurrence of both types of extremes could lead to even more profound consequences, however. For example, a dry period can have more negative consequences on agriculture if it is concomitant with or followed by a period of extremely high temperatures. This study analyzes the joint occurrence of very wet conditions and high/low temperature events at stations in Canada. More than one-half of the stations showed a significant positive relationship at the daily time scale between warm nights (daily minimum temperature greater than the 90th percentile) or warm days (daily maximum temperature above the 90th percentile) and heavy-precipitation events (daily precipitation exceeding the 75th percentile), with the greater frequencies found for the east and southwest coasts during autumn and winter. Cold days (daily maximum temperature below the 10th percentile) occur together with intense precipitation more frequently during spring and summer. Simulations by regional climate models show good agreement with observations in the seasonal and spatial variability of the joint distribution, especially when an ensemble of simulations was used.

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