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1.
An ocean biogeochemistry model was developed and incorporated into a global ocean general circulation model (LICOM) to form an ocean biogeochemistry general circulation model (OBGCM). The model was used to study the natural carbon cycle and the uptake and storage of anthropogenic CO2 in the ocean. A global export production of 12.5 Pg C yr-1 was obtained. The model estimated that in the pre-industrial era the global equatorial region within 15o of the equator released 0.97 Pg C yr-1 to the atmosphere, which was balanced by the gain of CO2 in other regions. The post-industrial air-sea CO2 flux indicated the oceanic uptake of CO2 emitted by human activities. An increase of 20－50 mol kg-1 for surface dissolved inorganic carbon (DIC) concentrations in the 1990s relative to pre-industrial times was obtained in the simulation, which was consistent with data-based estimates. The model generated a total anthropogenic carbon inventory of 105 Pg C as of 1994, which was within the range of estimates by other researchers. Various transports of both natural and anthropogenic DIC as well as labile dissolved organic carbon (LDOC) were estimated from the simulation. It was realized that the Southern Ocean and the high-latitude region of the North Pacific are important export regions where accumulative air-sea CO2 fluxes are larger than the DIC inventory, whereas the subtropical regions are acceptance regions. The interhemispheric transport of total natural carbon (DIC+LDOC) was found to be northward (0.11 Pg C yr-1), which was just balanced by the gain of carbon from the atmosphere in the Southern Hemisphere.  相似文献   

2.
Offsetting China's CO2 Emissions by Soil Carbon Sequestration   总被引：4，自引：0，他引：4  
R. Lal 《Climatic change》2004,65(3):263-275
Fossil fuel emissions of carbon (C) in China in 2000 was about 1 Pg/yr, which may surpass that of the U.S. (1.84 Pg C) by 2020. Terrestrial C pool of China comprises about 35 to 60 Pg in the forest and 120 to 186 Pg in soils. Soil degradation is a major issue affecting 145 Mha by different degradative processes, of which 126 Mha are prone to accelerated soil erosion. Similar to world soils, agricultural soils of China have also lost 30 to 50% or more of the antecedent soil organic carbon (SOC) pool.Some of the depleted SOC pool can be re-sequestered through restoration of degraded soils, and adoption of recommended management practices. The latter include conversion of upland crops to multiple cropping and rice paddies, adoption of integrated nutrient management (INM) strategies, incorporation of cover crops in the rotations cycle and adoption of conservation-effective systems including conservation tillage. A crude estimated potential of soil C sequestration in China is 119 to 226 Tg C/y of SOC and 7 to 138 Tg C/y for soil inorganic carbon (SIC) up to 50 years. The total potential of soil C sequestration is about 12 Pg, and this potential can offset about 25%of the annual fossil fuel emissions in China.  相似文献   

3.
Soil Carbon Sequestration in India   总被引：4，自引：0，他引：4  
R. Lal 《Climatic change》2004,65(3):277-296
With a large land area and diverse ecoregions, there is a considerable potential of terrestrial/soil carbon sequestration in India. Of the total land area of 329 million hectares (Mha), 297 Mha is the land area comprising 162 Mha of arable land, 69 Mha of forest and woodland, 11 Mha of permanent pasture, 8 Mha of permanent crops and 58 Mha is other land uses. Thesoil organic carbon (SOC) pool is estimated at 21 Pg (petagram = Pg = 1 ×1015 g= billion ton) to 30-cm depth and 63 Pg to 150-cm depth. The soil inorganic carbon (SIC) pool is estimated at 196 Pg to 1-m depth. The SOC concentration in most cultivated soils is less than 5 g/kg compared with 15 to 20 g/kg in uncultivated soils. Low SOC concentration is attributed to plowing, removal of crop residue and other biosolids, and mining of soil fertility. Accelerated soil erosion by water leads to emission of 6 Tg C/y. Important strategies of soil C sequestration include restoration of degraded soils, and adoption of recommended management practices (RMPs) of agricultural and forestry soils. Potential of soil C sequestration in India is estimated at 7 to 10 Tg C/y for restoration of degraded soils and ecosystems, 5 to 7 Tg C/y for erosion control, 6 to 7 Tg C/y for adoption of RMPs on agricultural soils, and 22 to 26 Tg C/y for secondary carbonates. Thus, total potential of soil C sequestration is 39 to 49 (44± 5) Tg C/y.  相似文献   

4.
The interest in the national levels of the terrestrial carbon sink and its spatial and temporal variability with the climate and CO2 concentrations has been increasing. How the climate and the increasing atmospheric CO2 concentrations in the last century affect the carbon storage in continental China was investigated in this study by using the Modified Sheffield Dynamic Global Vegetation Model (M-SDGVM). The estimates of the M-SDGVM indicated that during the past 100 years a combination of increasing CO2 with historical temperature and precipitation variability in continental China have caused the total vegetation carbon storage to increase by 2.04 Pg C, with 2.07 Pg C gained in the vegetation biomass but 0.03 Pg C lost from the organic soil carbon matter. The increasing CO2 concentration in the 20th century is primarily responsible for the increase of the total potential vegetation carbon. These factorial experiments show that temperature variability alone decreases the total carbon storage by 1.36 Pg C and precipitation variability alone causes a loss of 1.99 Pg C. The effect of the increasing CO2 concentration alone increased the total carbon storage in the potential vegetation of China by 3.22 Pg C over the past 100 years. With the changing of the climate, the CO2 fertilization on China's ecosystems is the result of the enhanced net biome production (NBP), which is caused by a greater stimulation of the gross primary production (GPP) than the total soil-vegetation respiration. Our study also shows notable interannual and decadal variations in the net carbon exchange between the atmosphere and terrestrial ecosystems in China due to the historical climate variability.  相似文献   

5.
A process-based approach to modelling the effects of land use change and climate change on the carbon balance of terrestrial ecosystems was applied at global scale. Simulations were run both with and without land use change. In the absence of land use change between 1700 and 1990, carbon storage in terrestrial ecosystems was predicted to increase by 145 Pg C. When land use change was represented during this period, terrestrial ecosystems became a net source of 97 Pg C. Land use change was directly responsible for a flux of 222 Pg C, slightly higher but close to estimates from other studies. The model was then run between 1990 and 2100 with a climate simulated by a GCM. Simulations were run with three land use change scenarios: 1. no land use change; 2. land use change specified by the SRES B2 scenario, and; 3. land use change scaled with population change in the B2 scenario. In the first two simulations with no or limited land use change, the net terrestrial carbon sink was substantial (358 and 257 Pg C, respectively). However, with the population-based land-use change scenario, the losses of carbon through land use change were close to the carbon gains through enhanced net ecosystem productivity, resulting in a net sink near zero. Future changes in land use are highly uncertain, but will have a large impact on the future terrestrial carbon balance. This study attempts to provide some bounds on how land use change may affect the carbon sink over the nextcentury.  相似文献   

6.
Monitoring atmospheric carbon dioxide(CO_2) from space-borne state-of-the-art hyperspectral instruments can provide a high precision global dataset to improve carbon flux estimation and reduce the uncertainty of climate projection. Here, we introduce a carbon flux inversion system for estimating carbon flux with satellite measurements under the support of "The Strategic Priority Research Program of the Chinese Academy of Sciences—Climate Change: Carbon Budget and Relevant Issues". The carbon flux inversion system is composed of two separate parts: the Institute of Atmospheric Physics Carbon Dioxide Retrieval Algorithm for Satellite Remote Sensing(IAPCAS), and Carbon Tracker-China(CT-China), developed at the Chinese Academy of Sciences. The Greenhouse gases Observing SATellite(GOSAT) measurements are used in the carbon flux inversion experiment. To improve the quality of the IAPCAS-GOSAT retrieval, we have developed a post-screening and bias correction method, resulting in 25%–30% of the data remaining after quality control. Based on these data, the seasonal variation of XCO_2(column-averaged CO_2dry-air mole fraction) is studied, and a strong relation with vegetation cover and population is identified. Then, the IAPCAS-GOSAT XCO_2 product is used in carbon flux estimation by CT-China. The net ecosystem CO_2 exchange is-0.34 Pg C yr~(-1)(±0.08 Pg C yr~(-1)), with a large error reduction of 84%, which is a significant improvement on the error reduction when compared with in situ-only inversion.  相似文献   

7.
There is growing concern that increasing concentrations of greenhouse gases in the atmosphere have been responsible for global warming through their effect on radiation balance and temperature. The magnitude of emissions and the relative importance of different sources vary widely, regionally and locally. The Indus Basin of Pakistan is the food basket of the country and agricultural activities are vulnerable to the effects of global warming due to accelerated emissions of GHGs. Many developments have taken place in the agricultural sector of Pakistan in recent decades in the background of the changing role of the government and the encouragement of the private sector for investment in new ventures. These interventions have considerable GHG emission potential. Unfortunately, no published information is currently available on GHG concentrations in the Indus Basin to assess their magnitude and emission trends. The present study is an attempt to estimate GHG （CO2, CH4 and N2O） emissions arising from different agro-ecosystems of Indus Basin. The GHGs were estimated mostly using the IPCC Guidelines and data from the published literature. The results showed that CH4 emissions were the highest （4.126 Tg yr^-1） followed by N20 （0.265 Tg yr^-1） and CO2 （52.6 Tg yr^-1）. The sources of CH4 are enteric fermentation, rice cultivation and cultivation of other crops. N2O is formed by microbial denitrification of NO3 produced from applied fertilizer-N on cropped soils or by mineralization of native organic matter on fallow soils. CO2 is formed by the burning of plant residue and by soil respiration due to the decomposition of soil organic matter.  相似文献   

8.
In this study, the diurnal and seasonal variations of CO2 fluxes in a subtropical mixed evergreen forest in Ningxiang of Hunan Province, part of the East Asian monsoon region, were quantified for the first time. The fluxes were based on eddy covariance measurements from a newly initiated flux tower. The relationship between the CO2 fluxes and climate factors was also analyzed. The results showed that the target ecosystem appeared to be a clear carbon sink in 2013, with integrated net ecosystem CO2exchange(NEE), ecosystem respiration(RE), and gross ecosystem productivity(GEP) of-428.8, 1534.8 and1963.6 g C m-2yr-1, respectively. The net carbon uptake(i.e. the-NEE), RE and GEP showed obvious seasonal variability,and were lower in winter and under drought conditions and higher in the growing season. The minimum NEE occurred on12 June(-7.4 g C m-2d-1), due mainly to strong radiation, adequate moisture, and moderate temperature; while a very low net CO2 uptake occurred in August(9 g C m-2month-1), attributable to extreme summer drought. In addition, the NEE and GEP showed obvious diurnal variability that changed with the seasons. In winter, solar radiation and temperature were the main controlling factors for GEP, while the soil water content and vapor pressure deficit were the controlling factors in summer. Furthermore, the daytime NEE was mainly limited by the water-stress effect under dry and warm atmospheric conditions, rather than by the direct temperature-stress effect.  相似文献   

9.
1980～2010年华北平原农田土壤有机碳的时空变化   总被引：2，自引：0，他引：2  
利用农业生态系统过程模型(Agricultural Production Systems s IMulator,APSIM),研究了1980~2010年间中国华北平原农田土壤有机碳(Soil Organic Carbon,SOC)的时空变化。模型验证结果表明,校正后的APSIM模型总体能够较好地模拟徐州、郑州和昌平3个长期定位试验站点中各处理下小麦和玉米的产量变化以及SOC的变化。区域模拟结果显示,1980~2010年间华北平原大部分农田SOC呈增加趋势,仅河北省的北部、山东省中部和东部部分地区农田SOC减少。华北平原总的农田面积约为24.52 Mha(1 ha=0.01 km2),其SOC密度的平均变化速率为0.35 Mg(C)ha-1 a-1,总的SOC贮量增加了约257.43 Tg。在京津冀地区、山东省以及河南省的农田中,SOC分别平均增加了102.05、59.82、95.56 Tg。SOC的增加,主要归功于过去几十年里外源碳投入量的增加。  相似文献   

10.
Increased Carbon Sink in Temperate and Boreal Forests   总被引：6，自引：0，他引：6  
An intense search is under way to identify the `missing sink' in the world carbon budget of perhaps 2 Pg year–1 (petagrams, or billiontonnes) of carbon, but its location and mechanism have proved elusive. Here we use a new forest inventory data set to estimate the carbon sink and the carbon pool of woody biomass in 55 countries that account for nearly all temperate or boreal forests and approximately half the world's total forest area. In each country there was a net accumulation of biomass; together, the carbon sink of woody biomass was 0.88 Pg year–1 during the 1990swith estimated uncertainty from 0.71 to 1.1 Pg year–1. Thisestimate, already about half of the missing sink, would probably be even larger if carbon accumulation in soil and detritus were also accounted for, but we are unable to quantify that additional sink. The sink is twice that estimated for the woody biomass of these forests a decade ago due to higher estimates for tree growth throughout the region and decreased timber harvests in Russia. In contrast, the new data indicate a carbon pool that is smaller than earlier estimates because of improved data for Russia and Australia.  相似文献   

11.
陆地生态系统碳汇显著降低大气CO2浓度上升和全球变暖的速率,受人类活动和气候变化的影响,陆地生态系统碳通量具有强烈的时空变化,其估算结果仍存在较大的不确定性,不同因子的贡献尚不清晰。为此,利用遥感驱动的陆地生态系统过程模型BEPS模拟分析了1981—2019年全球陆地生态系统碳通量的时空变化特征,评价了大气CO2浓度、叶面积指数（Leaf Area Index,LAI）、氮沉降、气候变化对全球陆地生态系统碳收支变化的贡献。1981—2019年全球陆地生态系统总初级生产力（Gross Primary Productivity,GPP）、净初级生产力（Net Primary Productivity,NPP）和净生态系统生产力（Net Ecosystem Productivity,NEP）的平均值分别为115.3、51.3和2.7 Pg·a-1（以碳质量计,下同）,上升速率分别为0.47、0.21和0.06 Pg·a-1。全球大部分区域GPP和NPP显著增加,NEP显著上升（p<0.05）的区域明显少于GPP和NPP。1981—2019年,全球NEP累积为105.2 Pg,森林、稀树草原及灌木、农田和草地的贡献分别为76.4、15.8、9.4和3.6 Pg。CO2浓度、LAI、氮沉降和气候变化各自对NEP的累积贡献分别为58.4、20.6、0.7和-43.6 Pg,全部4个因子变化对NEP的累积贡献为39.8 Pg,其中CO2浓度上升是近40 a全球陆地生态系统NEP上升的主要贡献因子,其次为LAI。  相似文献   

12.
A terrestrial biogeochemical model (CASACNP) was coupled to a land surface model (the Common Land Model,CoLM) to simulate the dynamics of carbon substrate in soil and its limitation on soil respiration.The combined model,CoLM CASACNP,was able to predict long-term carbon sources and sinks that CoLM alone could not.The coupled model was tested using measurements of belowground respiration and surface fluxes from two forest ecosystems.The combined model simulated reasonably well the diurnal and seasonal variations of net ecosystem carbon exchange,as well as seasonal variation in the soil respiration rate of both the forest sites chosen for this study.However,the agreement between model simulations and actual measurements was poorer under dry conditions.The model should be tested against more measurements before being applied globally to investigate the feedbacks between the carbon cycle and climate change.  相似文献   

13.
An ocean carbon cycle model driven by a constant flow field produced by a two-dimensional thermohaline circu-lation model is developed. Assuming that the biogenic carbon in the oceans is in a dynamic equilibrium, the inorganic carbon cycle is investigated. Before the oceanic uptake of CO2 is carried out, the investigation of 14C distributions in the oceans, including natural and bomb-produced 14C, is conducted by using different values of the exchange coefficient of CO2 for different flow fields (different vertical diffusivities) to test the performance of the model. The suitable values of the exchange coefficient and vertical diffusivities are chosen for the carbon cycle model. Under the forcing of given preindustrial atmospheric CO2 concentration of 280 ppmv, the carbon cycle model is integrated for seven thousand years to reach a steady state. For the human perturbation, two methods including the prescribed at-mospheric pCO2 and prescribed industrial emissions are used in this work. The results from the prescribed atmospher-ic pCO2 show that the oceans take up 36% of carbon dioxide released by human activities for the period of 1980-1989, while the results from the prescribed industrial emission rates show that the oceans take up 34% of car-bon dioxide emitted by industrial sources for the same period. By using the simple method of subtracting industrial emission rate from the total atmosphere+ocean accumulating rate, it can be deduced that before industrial revolution a non-industrial source exists, while after 1940 an extra sink is needed, and that a total non-industrial source of 45 GtC is obtained for the period of 1790-1990.  相似文献   

14.
The maximum rate of carboxylation(Vcmax) is a key photosynthetic parameter for gross primary production(GPP) estimation in terrestrial biosphere models. A set of observation-based Vcmax values, which take the nitrogen limitation on photosynthetic rates into consideration, are used in version 4.5 of the Community Land Model(CLM4.5). However, CLM4.5 with carbon-nitrogen(CN) biogeochemistry(CLM4.5-CN) still uses an independent decay coefficient for nitrogen after the photosynthesis calculation. This means that the nitrogen limitation on the carbon cycle is accounted for twice when CN biogeochemistry is active. Therefore, to avoid this double nitrogen down-regulation in CLM4.5-CN, the original Vcmax scheme is revised with a new one that only accounts for the transition between Vcmax and its potential value(without nitrogen limitation). Compared to flux towerbased observations, the new Vcmax scheme reduces the root-mean-square error(RMSE) in GPP for mainland China by 13.7 g C m-2 yr-1, with a larger decrease over humid areas(39.2 g C m-2 yr-1). Moreover, net primary production and leaf area index are also improved, with reductions in RMSE by 0.8% and 11.5%, respectively.  相似文献   

15.
A regional nitrogen cycle model, named IAP-N, was designed for simulating regional nitrogen （N） cycling and calculating N fluxes flowing among cultivated soils, crops, and livestock, as well as human, atmospheric and other systems. The conceptual structure and calculation methods and procedures of this model are described in detail. All equations of the model are presented. In addition, definitions of all the involved variables and parameters are given. An application of the model in China at the national scale is presented. In this example, annual surpluses of consumed synthetic N fertilizer; emissions of nitrous oxide （N2O）, ammonia （NH3） and nitrogen oxide （NOx）; N loss from agricultural lands due to leaching and runoff; and sources and sinks of anthropogenic reactive N （Nr） were estimated for the period 1961-2004. The model estimates show that surpluses of N fertilizer started to occur in the mid 1990s and amounted to 5.7 Tg N yr^-1 in the early 2000s. N20 emissions related to agriculture were estimated as 0.69 Tg N yr^-1 in 2004, of which 58% was released directly from N added to agricultural soils. Total NH3 and NOx emissions in 2004 amounted to 4.7 and 4.9 Tg N yr^-1, respectively. About 3.9 Tg N yr^-1 of N was estimated to have flowed out of the cultivated soil layer in 2004, which accounted for 33% of applied synthetic N fertilizer. Anthropogenic Nr sources changed from 2.8 （1961） to 28.1 Tg N yr^-1 （2004）, while removal （sinks） changed from to 2.1 to 8.4 Tg N yr^-1. The ratio of anthropogenic Nr sources to sinks was only 1.4 in 1961 but 3.3 in 2004. Further development of the IAP-N model is suggested to focus upon： Ca） inter-comparison with other regional N models; （b） overcoming the limitations of the current model version, such as adaptation to other regions, high-resolution database, and so on; and （c） developing the capacity to estimate the safe threshold of anthropogenic Nr source to sink ratios.  相似文献   

16.
1. IntroductionAccording to the reconstruction of paleo-temperature based on δ18 O data of ice core in theGreenland (see Jouzel et al., 1987; Grootes et al.,1993; Blunier and Brook, 2001), the current inter-glacial epoch, the Holocene, began at ca. 11.5 thou-sand years before present (ka BP). Multiple sources(pollen data, macrofossils) reveal that the summer cli-mate in the Northern Hemisphere was warmer in theearly to middle Holocene (MH) (ca. 8-6ka BP) relativeto the present climate. …  相似文献   

17.
磷是植物生长必需的元素,磷缺乏将限制植被生产力及碳汇功能.为厘清全球大气磷沉降的时空格局,本文收集了 1959-2020年发表的396条观测资料.结果发现,全球大气磷沉降的几何均值为0.32 kg ha-1 yr-1,全球大气磷库约4.4Tg yr-1.与1959-2000年相比,近20年亚洲和欧洲大气磷沉降呈现上升趋势,主要来源是农业活动,沙尘传输和燃烧源排放.碳中和背景下,清洁空气行动是否会改变磷沉降的途径和形态,进而影响到生态系统的结构和功能,是需要回答的科学问题.  相似文献   

18.
Rice-wheat (R-W) rotation systems are ubiquitous in South and East Asia, and play an important role in modulating the carbon cycle and climate. Long-term, continuous flux measurements help in better understanding the seasonal and interannual variation of the carbon budget over R-W rotation systems. In this study, measurements of CO2 fluxes and meteorological variables over an R-W rotation system on the North China Plain from 2007 to 2010 were analyzed. To analyze the abiotic factors regulating Net Ecosystem Exchange (NEE), NEE was partitioned into gross primary production (GPP) and ecosystem respiration. Nighttime NEE or ecosystem respiration was controlled primarily by soil temperature, while daytime NEE was mainly determined by photosythetically active radiation (PAR). The responses of nighttime NEE to soil temperature and daytime NEE to light were closely associated with crop development and photosynthetic activity, respectively. Moreover, the interannual variation in GPP and NEE mainly depended on precipitation and PAR. Overall, NEE was negative on the annual scale and the rotation system behaved as a carbon sink of 982 g C m-2 per year over the three years. The winter wheat field took up more CO2 than the rice paddy during the longer growing season, while the daily NEE for wheat and rice were -2.35 and -3.96 g C m-2, respectively. After the grain harvest was subtracted from the NEE, the winter wheat field became a moderately strong carbon sink of 251-334 g C m-2 per season, whereas the rice paddy switched to a weak carbon sink of 107-132 per season.  相似文献   

19.
Net primary production （NPP） of crop represents the capacity of sequestrating atmospheric CO2 in agro-ecosystem, and it plays an important role in terrestrial carbon cycling. By linking the Crop-C model with climate change scenario projected by a coupled GCM FGOALS via geographical information system （GIS） techniques, crop NPP in China was simulated from 2000 to 2050. The national averaged surface air temperature from FGOALS is projected to increase by 1.0℃ over this period and the corresponding atmospheric CO2 concentration is 535 ppm by 2050 under the IPCC A1B scenario. With a spatial resolution of 10 ×10 km^2, model simulation indicated that an annual average increase of 0.6 Tg C yr^-1 （Tg=10^12 g） would be possible under the A1B scenario. The NPP in the late 2040s would increase by 5% （30 Tg C） within the 98×10^6 hm^2 cropland area in contrast with that in the early 2000s. A further investigation suggested that changes in the NPP would not be evenly distributed in China. A higher increase would occur in a majority of regions located in eastern and northwestern China, while a slight reduction would appear in Hebei and Tianjin in northern China. The spatial characteristics of the crop NPP change are attributed primarily to the uneven distribution of temperature change.  相似文献   

20.
Earth System Models （ESMs） are fundamental tools for understanding climate-carbon feedback. An ESM version of the Flexible Global Ocean-Atmosphere-Land System model （FGOALS） was recently developed within the IPCC AR5 Coupled Model Intercomparison Project Phase 5 （CMIP5） modeling framework, and we describe the development of this model through the coupling of a dynamic global vegetation and terrestrial carbon model with FGOALS-s2. The performance of the coupled model is evaluated as follows. The simulated global total terrestrial gross primary production （GPP） is 124.4 PgC yr-I and net pri- mary production （NPP） is 50.9 PgC yr-1. The entire terrestrial carbon pools contain about 2009.9 PgC, comprising 628.2 PgC and 1381.6 PgC in vegetation and soil pools, respectively. Spatially, in the tropics, the seasonal cycle of NPP and net ecosystem production （NEP） exhibits a dipole mode across the equator due to migration of the monsoon rainbelt, while the seasonal cycle is not so significant in Leaf Area Index （LAI）. In the subtropics, especially in the East Asian monsoon region, the seasonal cycle is obvious due to changes in temperature and precipitation from boreal winter to summer. Vegetation productivity in the northern mid-high latitudes is too low, possibly due to low soil moisture there. On the interannual timescale, the terrestrial ecosystem shows a strong response to ENSO. The model- simulated Nifio3.4 index and total terrestrial NEP are both characterized by a broad spectral peak in the range of 2-7 years. Further analysis indicates their correlation coefficient reaches -0.7 when NEP lags the Nifio3.4 index for about 1-2 months.  相似文献   

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