海洋和陆地碳循环对二氧化碳正负排放响应的模拟研究

doi:10.12006/j.issn.1673-1719.2024.058

摘要/Abstract

摘要：

人类活动导致大气浓度上升和全球变暖，威胁人类生存。CO₂移除作为一种可能的减缓全球变暖的手段，近年来受到了广泛关注。文中使用维多利亚大学地球系统模式（UVic ESCM)，模拟分析在工业革命前平衡状态下（大气CO₂浓度285×10^-6)，以不同强度脉冲形式施加的正负碳排放对碳循环的影响。模拟结果表明，在100 Pg C正脉冲排放情景下，脉冲排放后第100（1000）年，排放到大气中的CO₂有28%（18%）滞留在大气中，38%（61%）和34%（21%）分别被海洋和陆地吸收。在100 Pg C负脉冲排放情景下，海洋和陆地向大气释放CO₂，从而减弱CO₂移除的效果。负排放后第100（1000）年，大气中减少的CO₂占初始CO₂移除量的23%（12%)，其余36%（65%）和41%（23%）分别被海洋和陆地碳释放抵消。不同强度正负脉冲碳排放情景对比结果显示，正脉冲情景下累积空气分数始终高于同等强度负脉冲情景下累积去除分数，这说明正负脉冲碳排放情景下海陆碳循环的响应具有不对称性，要抵消正排放造成的大气CO₂浓度上升，需要进行更高强度的负排放。

关键词: 气候变化, CO₂移除, 碳循环, 地球系统模拟

Abstract:

Human activities lead to increase in atmospheric CO₂ concentrations and global warming, threatening human survival. As a potential method to mitigate global warming, CO₂ removal has garnered extensive attention in recent years. We employed the University of Victoria Earth System Climate Model (UVic ESCM) to simulate and analyze the effects of both positive and negative CO₂ pulses of various intensity on the carbon cycle starting from preindustrial equilibrium (CO₂ concentration: 285×10^-6). The results show that in the 100 Pg C positive CO₂ pulse emission scenario, 100 (1000) years after imposing the CO₂ pulse, only 28% (18%) of the CO₂ emission remains in the atmosphere, the ocean absorbs about 38% (61%) of the CO₂ emission, the land absorbs about 34% (21%) of the CO₂ emission. In the 100 Pg C negative CO₂ pulse emission scenario, the ocean and the land releases CO₂ to the atmosphere, weakening the effect of CO₂ removal. 100 (1000) years after imposing the CO₂ pulse, only 23% (12%) of the initial CO₂ removal from the atmosphere remains, with 36% (65%) offset by ocean carbon release, 41% (23%) offset by land carbon release. According to different positive and negative pulse scenarios, the cumulative airborne fraction in the positive pulse scenario is always higher than cumulative removal fraction in the negative pulse scenario of the same intensity, which indicates that the positive and negative pulse carbon emission scenario responses of the sea and land carbon cycles are asymmetric. It means that negative emissions of higher intensities are needed to offset the atmospheric CO₂ concentration increases caused by positive emissions.

Key words: Climate change, CO₂ removal, Carbon cycle, Earth System Modeling

张靖宇, 曹龙. 海洋和陆地碳循环对二氧化碳正负排放响应的模拟研究[J]. 气候变化研究进展, 2024, 20(4): 416-427.

ZHANG Jing-Yu, CAO Long. Simulated response of the ocean and land carbon cycles to positive and negative CO₂ emissions[J]. Climate Change Research, 2024, 20(4): 416-427.

图/表 9

图1 全耦合试验中各情景下大气CO2浓度较工业革命前随时间的演变注：100年后的横坐标间距为前100年的1/10。

Fig. 1 Atmospheric CO2 concentration change in the full coupling experiments

图2 全耦合试验中100 Pg C (a)、-100 Pg C (b)脉冲排放情景下大气、海洋和陆地碳库储量变化

Fig. 2 Changes in carbon storage of atmospheric, marine and land carbon reservoirs in +100 Pg C scenario (a) and -100 Pg C scenario (b)

表1 全耦合试验中大气、海洋、陆地碳储量变化占脉冲碳排放的份额

Table 1 The change of atmospheric, ocean and land carbon storage in the share of pulse carbon emissions in the fully coupled experiments

图3 全耦合试验中全球海-气碳通量(a)和海洋碳储量(b)随时间的演变

Fig. 3 Global average air-sea carbon flux change (a) and ocean carbon storage change (b) in fully coupled experiments

图4 全耦合模拟中，+100 Pg C (a)、-100 Pg C (b)脉冲碳排放情景下第10年海-气碳通量变化的空间分布以及不对称性(c) 注：不对称性指正脉冲排放情景下的海-气碳通量与相同强度负脉冲排放情景下的海-气碳通量之和不为零。

Fig. 4 Spatial changes of air-sea carbon flux (a, b) in the 10th year after the ±100 Pg C pulse carbon emissions and asymmetry (c) in fully coupled experiments

图5 全耦合（COU）试验与仅耦合生物化学过程试验（BGC）中海表DIC的缓冲因子随时间的演变注：虚线与相同颜色的实线几乎完全重合，表明是否考虑气候变化对DIC缓冲因子的影响非常小。

Fig. 5 Timing diagram of DIC buffer factor change in fully coupled experiments (COU) and biogeochemically coupled experiments (BGC)

图6 全耦合模拟试验中全球陆-气碳通量(a)、陆地碳储量(b)、全球植物净初级生产力(c)、陆地植物总碳储量(d)、全球土壤微生物呼吸速率(e)，以及土壤总碳储量(f)较工业革命前随时间的演变

Fig. 6 Global average air-land carbon flux change (a), land carbon storage change (b), vegetation NPP change (c), vegetation carbon storage change (d), global average soil respiration change (e), and soil carbon storage change (f) in fully coupled experiments

图7 全耦合试验中，+100 Pg C (a)、-100 Pg C (b)脉冲碳排放实施后第10年陆-气碳通量变化的空间分布及不对称性(c)

Fig. 7 Spatial changes of air-land carbon flux (a, b) in 10th year after the ±100 Pg C pulse carbon emissions and asymmetry (c) in fully coupled experiments

图8 ±100 Pg C脉冲碳排放情景下，COU试验和BGC试验中大气CO2浓度(a)、海表CO2分压(b)、海-气碳通量(c)、海洋碳储量(d)、陆-气碳通量(e)、陆地碳储量(f)、植物NPP (g)、植被碳储量(h)、土壤呼吸速率(i)以及土壤碳储量(j)变化的差异

Fig. 8 Differences of atmospheric CO2 concentration changes (a), sea surface CO2 pressure changes (b), air-sea carbon flux changes (c), ocean carbon storage changes (d), air-land carbon flux changes (e), land carbon storage changes (f), vegetation NPP changes (g), vegetation carbon storage changes (h), soil respiration changes (i) and soil carbon storage changes (j) variables between the COU and BGC experiments in the ± 100 Pg C pulse carbon emission scenarios

参考文献 28

[1]	IPCC. Climate change 2021: the physical science basis[M]. Cambridge: Cambridge University Press, 2021
[2]	Masson-Delmotte V, Zhai P, P?rtner H O, et al. Global warming of 1.5 ℃: IPCC special report on impacts of global warming of 1.5 ℃ above pre-industrial levels in context of strengthening response to climate change, sustainable development, and efforts to eradicate poverty[M]. Cambridge: Cambridge University Press, 2022
[3]	Olhoff A, Christensen J M. Emissions gap report 2020[J]. UNEP DTU Partnership, 2020: 128
[4]	曹龙. IPCC AR6 报告解读: 气候系统对二氧化碳移除响应[J]. 气候变化研究进展, 2021, 17 (6): 664-670.
	Cao L. Climate system response to carbon dioxide removal[J]. Climate Change Research, 2021, 17 (6): 664-670 (in Chinese)
[5]	MacDougall A H. Reversing climate warming by artificial atmospheric carbon-dioxide removal: can a Holocene-like climate be restored?[J]. Geophysical Research Letters, 2013, 40 (20): 5480-5485
[6]	Zickfeld K, Eby M, Weaver A J, et al. Long-term climate change commitment and reversibility: an EMIC intercomparison[J]. Journal of Climate, 2013, 26 (16) : 5782-5809
[7]	Schwinger J, Tjiputra J. Ocean carbon cycle feedbacks under negative emissions[J]. Geophysical Research Letters, 2018, 45 (10): 5062-5070
[8]	Joos F, Roth R, Fuglestvedt J S, et al. Carbon dioxide and climate impulse response functions for the computation of greenhouse gas metrics: a multi-model analysis[J]. Atmospheric Chemistry and Physics, 2013, 13 (5): 2793-2825
[9]	Jones C D, Arora V, Friedlingstein P, et al. C4MIP: The coupled climate-carbon cycle model intercomparison project: experimental protocol for CMIP6[J]. Geoscientific Model Development, 2016, 9 (8): 2853-2880
[10]	Zickfeld K, Azevedo D, Mathesius S, et al. Asymmetry in the climate: carbon cycle response to positive and negative CO₂ emissions[J]. Nature Climate Change, 2021, 11 (7): 613-617
[11]	Weaver A J, Eby M, Wiebe E C, et al. The UVic Earth System Climate Model:model description, climatology, and applications to past, present and future climates [M]. Routledge:Data, Models and Analysis, 2019: 169-236
[12]	Fanning A F, Weaver A J. An atmospheric energy-moisture balance model: climatology, interpentadal climate change, and coupling to an ocean general circulation model[J]. Journal of Geophysical Research: Atmospheres, 1996, 101 (D10): 15111-15128
[13]	Pacanowski R C. MOM 2 documentation, user’s guide and reference manual[J]. GFDL Ocean Group Tech Rep, 1995 (3): 232
[14]	Bitz C M, Lipscomb W H. An energy-conserving thermodynamic model of sea ice[J]. Journal of Geophysical Research: Oceans, 1999, 10 (C7): 15669-15677
[15]	Schmittner A, Oschlies A, Matthews H D, et al. Future changes in climate, ocean circulation, ecosystems, and biogeochemical cycling simulated for a business-as-usual CO₂ emission scenario until year 4000 AD[J]. Global Biogeochemical Cycles, 2008, 22 (1): GB1013
[16]	Orr J, Najjar R, Sabine C, et al. Abiotic-HOWTO, internal OCMIP report[R]. Saclay: LSCE/CEA, 1999: 29
[17]	Meissner K, Weaver A, Matthews H, et al. The role of land surface dynamics in glacial inception: a study with the UVic Earth System Model[J]. Climate Dynamics, 2003, 21: 515-537
[18]	Cao L, Jiang J. Simulated effect of carbon cycle feedback on climate response to solar geoengineering[J]. Geophysical Research Letters, 2017, 44 (24): 12, 484-412, 491
[19]	MacDougall A H. Limitations of the 1% experiment as the benchmark idealized experiment for carbon cycle intercomparison in C4MIP[J]. 2019, 12 (2): 597-611
[20]	Mengis N, Keller D P, MacDougall A H, et al. Evaluation of the University of Victoria Earth System Climate Model version 2.10 (UVic ESCM 2.10)[J]. Geoscientific Model Development, 2020, 13 (9): 4183-4204
[21]	Eby M, Weaver A J, Alexander K, et al. Historical and idealized climate model experiments: an intercomparison of Earth System Models of intermediate complexity[J]. Climate of the Past, 2013, 9 (3): 1111-1140
[22]	Friedlingstein P, Cox P, Betts R, et al. Climate: carbon cycle feedback analysis: results from the C4MIP model intercomparison[J]. Journal of Climate, 2006, 19 (14): 3337-3353
[23]	Weber S, Drijfhout S, Abe-Ouchi A, et al. The modern and glacial overturning circulation in the Atlantic ocean in PMIP coupled model simulations[J]. Climate of the Past, 2007, 3 (1): 51-64
[24]	Gregory J, Dixon K, Stouffer R, et al. A model intercomparison of changes in the Atlantic thermohaline circulation in response to increasing atmospheric CO₂ concentration[J]. Geophysical Research Letters, 2005, 32 (12): L12703
[25]	Keller D P, Lenton A, Scott V, et al. The Carbon Dioxide Removal Model Intercomparison Project (CDRMIP): rationale and experimental protocol for CMIP6[J]. Geoscientific Model Development, 2018, 11 (3): 1133-1160
[26]	Gloor M, Sarmiento J L, Gruber N. What can be learned about carbon cycle climate feedbacks from the CO₂ airborne fraction?[J]. Atmospheric Chemistry and Physics, 2010, 10 (16): 7739-7751
[27]	Revelle R, Suess H E. Carbon dioxide exchange between atmosphere and ocean and the question of an increase of atmospheric CO₂ during the past decades[J]. Tellus, 1957, 9 (1): 18-27
[28]	Sabine C L, Feely R A, Gruber N, et al. The oceanic sink for anthropogenic CO₂[J]. Science, 2004, 305 (5682): 367-371 doi: 10.1126/science.1097403 pmid: 15256665