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1.
Jian Ni 《Climatic change》2001,49(3):339-358
The carbon storage of terrestrial ecosystems in China was estimated using acommon carbon density method for vegetation and soils relating to thevegetation types. Usingmedian density estimates, carbon storage of 35.23 Gt (1 Gt = 1015g) in biomass and119.76 Gt in soils with total of 154.99 Gt were calculated based on thebaseline distribution of37 vegetation types. Total carbon storage of the median estimates at differentspatial resolutionswas 153.43, 158.08 and 158.54 Gt, respectively, for the fine (10),median (20) and coarse (30)latitude × longitude grids. There were differences of –1.56, +3.09and +3.55 Gt carbon storagebetween baseline vegetation and those at different spatial resolutions. Changein mappingresolution would change area estimates and hence carbon storage estimates. Thefiner the spatialresolution in mapping vegetation, the closer the carbon storage to thebaseline estimation. Carbonstorage in vegetation and soils for baseline vegetation is quite similar tothat of biomes predictedby BIOME3 for the present climate and CO2 concentration of 340ppmv. Climate changealone as well as climate change with elevated CO2 concentrationwill produce an increasein carbon stored by vegetation and soils, especially a larger increase in thesoils. Total mediancarbon storage of terrestrial ecosystems in China will increase by 5.09 Gt and15.91 Gt for theclimate scenario at CO2 concentration of 340 ppmv and 500 ppmv,respectively. This ismainly due to changes in vegetation areas and the effects of changes inclimate and CO2concentration.  相似文献   

2.
In order to estimate the production of charcoal and the atmospheric emissions of trace gases volatilized by burning we have estimated the global amounts of biomass which are affected by fires. We have roughly calculated annual gross burning rates ranging between about 5 Pg and 9 Pg (1 Pg = 1015 g) of dry matter (2–4 Pg C). In comparison, about 9–17 Pg of above-ground dry matter (4–8 Pg C) is exposed to fires, indicating a worldwide average burning efficiency of about 50%. The production of dead below-ground dry matter varies between 6–9 Pg per year. We have tentatively indicated the possibility of a large production of elemental carbon (0.5–1.7 Pg C/yr) due to the incomplete combustion of biomass to charcoal. This provides a sink for atmospheric CO2, which would have been particularly important during the past centuries. From meager statistical information and often ill-documented statements in the literature, it is extremely difficult to calculate the net carbon release rates to the atmosphere from the biomass changes which take place, especially in the tropics. All together, we calculate an overall effect lof the biosphere on the atmospheric carbon dioxide budget which may range between the possibilities of a net uptake or a net release of about 2 Pg C/yr. The release of CO2 to the atmosphere by deforestation projects may well be balanced by reforestation and by the production of charcoal. Better information is needed, however, to make these estimates more reliable.Now at the Max-Planck-Institute for Chemistry, Mainz, FRG.The National Center for Atmospheric Research is sponsored by the National Science Foundation.  相似文献   

3.
Biomass is often seen as a key component of future energy systems as it can be used for heat and electricity production, as a transport fuel, and a feedstock for chemicals. Furthermore, it can be used in combination with carbon capture and storage to provide so-called “negative emissions”. At the same time, however, its production will require land, possibly impacting food security, land-based carbon stocks, and other environmental services. Thus, the strategies adopted in the supply, conversion, and use of biomass have a significant impact on its effectiveness as a climate change mitigation measure. We use the IMAGE 3.0 integrated assessment model to project three different global, long term scenarios spanning different socioeconomic futures with varying rates of population growth, economic growth, and technological change, and investigate the role of biomass in meeting strict climate targets. Using these scenarios we highlight different possibilities for biomass supply and demand, and provide insights on the requirements and challenges for the effective use of this resource as a climate change mitigation measure. The results show that in scenarios meeting the 1.5 °C target, biomass could exceed 20% of final energy consumption, or 115–180 EJPrim/yr in 2050. Such a supply of bioenergy can only be achieved without extreme levels land use change if agricultural yields improve significantly and effective land zoning is implemented. Furthermore, the results highlight that strict mitigation targets are contingent on the availability of advanced technologies such as lignocellulosic fuels and carbon capture and storage.  相似文献   

4.
The present study estimates the net emission of carbon from the forest sector in India. For the reference year (1986), the gross emission from deforestation in that year, plus committed emissions from deforestation in the preceding years, is estimated to be 64 × 106 t of C. The carbon sequestration (or net woody biomass accumulation in trees for long-term storage) from the area brought under tree plantations and the existing forest area under forest succession is estimated to offset the gross carbon emission in India, leading to no net emissions of carbon from the forest sector. Medium-term projections for India (for the year 2011) show that under a business as usual scenario at current rates of afforestation, projected carbon emissions would continue to be balanced by sequestration.  相似文献   

5.
The use of modern biomass for energy generation has been considered in many studies as a possible measure for reducing or stabilizing global carbon dioxide (CO2) emissions. In this paper we assess the impacts of large-scale global utilization of biomass on regional and grid scale land cover, greenhouse gas emissions, and carbon cycle. We have implemented in the global environmental change model IMAGE the LESS biomass intensive scenario, which was developed for the Second Assessment Report of IPCC. This scenario illustrates the potential for reducing energy related emission by different sets of fuel mixes and a higher energy efficiency. Our analysis especially covers different consequences involved with such modern biomass scenarios. We emphasize influences of CO2 concentrations and climate change on biomass crop yield, land use, competition between food and biomass crops, and the different interregional trade patterns for modern biomass based energy. Our simulations show that the original LESS scenario is rather optimistic on the land requirements for large-scale biomass plantations. Our simulations show that 797 Mha is required while the original LESS scenario is based on 550 Mha. Such expansion of agricultural land will influence deforestation patterns and have significant consequenses for environmental issues, such as biodiversity. Altering modern biomass requirements and the locations where they are grown in the scenario shows that the outcome is sensitive for regional emissions and feedbacks in the C cycle and that competition between food and modern biomass can be significant. We conclude that the cultivation of large quantities of modern biomass is feasible, but that its effectiveness to reduce emissions of greenhouse gases has to be evaluated in combination with many other environmental land use and socio-economic factors.  相似文献   

6.
Carbon sequestration is increasingly being promoted as a potential response to the risks of unrestrained emissions of CO2, either in place of or as a complement to reductions in the use of fossil fuels. However, the potential role of carbon sequestration as an (at-least partial) substitute for reductions in fossil fuel use can be properly evaluated only in the context of a long-term acceptable limit (or range of limits) to the increase in atmospheric CO2 concentration, taking into account the response of the entire carbon cycle to artificial sequestration. Under highly stringent emission-reduction scenarios for non-CO2 greenhouse gases, 450 ppmv CO2 is the equivalent, in terms of radiative forcing of climate,to a doubling of the pre-industrial concentration of CO2. It is argued in this paper that compliance with the United Nations Framework Convention on Climate Change (henceforth, the UNFCCC) implies that atmospheric CO2 concentration should be limited, or quickly returned to, a concentration somewhere below 450 ppmv. A quasi-one-dimensional coupled climate-carbon cycle model is used to assess the response of the carbon cycle to idealized carbon sequestration scenarios. The impact on atmospheric CO2 concentration of sequestering a given amount of CO2 that would otherwise be emitted to the atmosphere, either in deep geological formations or in the deep ocean, rapidly decreases over time. This occurs as a result of a reduction in the rate of absorption of atmospheric CO2 by the natural carbon sinks (the terrestrial biosphere and oceans) in response to the slower buildup of atmospheric CO2 resulting from carbon sequestration. For 100 years of continuous carbon sequestration, the sequestration fraction (defined as the reduction in atmospheric CO2 divided by the cumulative sequestration) decreases to 14% 1000 years after the beginning of sequestration in geological formations with no leakage, and to 6% 1000 years after the beginning of sequestration in the deep oceans. The difference (8% of cumulative sequestration) is due to an eflux from the ocean to the atmosphere of some of the carbon injected into the deep ocean.The coupled climate-carbon cycle model is also used to assess the amount of sequestration needed to limit or return the atmospheric CO2 concentration to 350–400 ppmv after phasing out all use of fossil fuels by no later than 2100. Under such circumstances, sequestration of 1–2 Gt C/yr by the latter part of this century could limit the peak CO2 concentration to 420–460 ppmv, depending on how rapidly use of fossilfuels is terminated and the strength of positive climate-carbon cycle feedbacks. To draw down the atmospheric CO2 concentration requires creating negative emissions through sequestration of CO2 released as a byproduct of the production of gaseous fuels from biomass primary energy. Even if fossil fuel emissions fall to zero by 2100, it will be difficult to create a large enough negative emission using biomass energy to return atmospheric CO2 to 350 ppmv within 100 years of its peak. However, building up soil carbon could help in returning CO2 to 350 ppmv within 100 years of its peak. In any case, a 100-year period of climate corresponding to the equivalent of a doubled-CO2 concentration would occur before temperatures decreased. Nevertheless, returning the atmospheric CO2concentration to 350 ppmv would reduce longterm sea level rise due to thermal expansion and might be sufficient to prevent the irreversible total melting of the Greenland ice sheet, collapse of the West Antarctic ice sheet, and abrupt changes in ocean circulation that might otherwise occur given a prolonged doubled-CO2 climate. Recovery of coral reef ecosystems, if not already driven to extinction, could begin.  相似文献   

7.
This paper addresses the use of radar remote sensing to map forest above-ground biomass, and discusses the use of biomass maps to test a dynamic vegetation model that identifies carbon sources and sinks and predicts their variation over time. For current radar satellite data, only the biomass of young/sparse forests or regrowth after disturbances can be recovered. An example from central Siberia illustrates that biomass can be measured by radar at a continental scale, and that a significant proportion of the Siberian forests have biomass values less than 50 tonnes/ha. Comparison between the radar map and calculations by the Sheffield Dynamic Global Vegetation Model (SDGVM) indicates that the model considerably overestimates biomass; under-representation of managed areas, disturbed areas and areas of low site quality in the model are suggested reasons for this effect. A case study carried out at the Büdingen plantation forest in Germany supports the argument that inadequate representations of site quality and forest management may cause model overestimates of biomass. Comparison of the calculated biomass of stands planted after 1990 with biomass estimates by radar allows identification of forest stands where the growth conditions assumed by the model are not valid. This allows a quality check on model calculations of carbon fluxes: only calculations for stands where there is good agreement between the data and the model predictions should be accepted. Although the paper only uses the SDGVM model, similar effects are likely in other dynamic vegetation models, and the results show that model calculations attempting to quantify the role of forests as carbon sources or sinks could be qualified and potentially improved by exploiting remotely sensed measurements of biomass.  相似文献   

8.
This paper addresses the use of radar remote sensing to map forest above-ground biomass, and discusses the use of biomass maps to test a dynamic vegetation model that identifies carbon sources and sinks and predicts their variation over time. For current radar satellite data, only the biomass of young/sparse forests or regrowth after disturbances can be recovered. An example from central Siberia illustrates that biomass can be measured by radar at a continental scale, and that a significant proportion of the Siberian forests have biomass values less than 50 tonnes/ha. Comparison between the radar map and calculations by the Sheffield Dynamic Global Vegetation Model (SDGVM) indicates that the model considerably overestimates biomass; under-representation of managed areas, disturbed areas and areas of low site quality in the model are suggested reasons for this effect. A case study carried out at the Büdingen plantation forest in Germany supports the argument that inadequate representations of site quality and forest management may cause model overestimates of biomass. Comparison of the calculated biomass of stands planted after 1990 with biomass estimates by radar allows identification of forest stands where the growth conditions assumed by the model are not valid. This allows a quality check on model calculations of carbon fluxes: only calculations for stands where there is good agreement between the data and the model predictions should be accepted. Although the paper only uses the SDGVM model, similar effects are likely in other dynamic vegetation models, and the results show that model calculations attempting to quantify the role of forests as carbon sources or sinks could be qualified and potentially improved by exploiting remotely sensed measurements of biomass.  相似文献   

9.
A methodology is presented to construct supply curves and cost–supply curves for carbon plantations based on land-use scenarios from the Integrated Model to Assess the Global Environment (IMAGE 2). A sensitivity analysis for assessing which factors are most important in shaping these curves is also presented. In the IPCC SRES B2 Scenario, the carbon sequestration potential on abandoned agricultural land increases from 60 MtC/year in 2010 to 2,700 MtC/year in 2100 for prices up to 1,000 $/tC, assuming harvest when the mean annual increment decreases and assuming no environmental, economical or political barriers in the implementation-phase. Taking these barriers into consideration would reduce the potential by at least 60%. On the other hand, the potential will increase 55 to 75% if plantations on harvested timberland are considered. Taking into account land and establishment costs, the largest part of the potential up to 2025 can be supplied below 100 $/tC (In this article all dollar values are in US dollars of 1995, unless indicated otherwise.). Beyond 2050, more than 50% of the costs come to over 200 $/tC. Compared to other mitigation options, this is relative cheap. So a large part of the potential will likely be used in an overall mitigation strategy. However, since huge emission reductions are probably needed, the relative contribution of plantations will be low (around 3%). The largest source of uncertainty with respect to both potentials and costs is the growth rate of plantations compared to the natural vegetation.  相似文献   

10.
Atmospheric aerosol samples were collected in the Ivory Coast, primarily at Lamto (6°N, 5°W) between 1979 and 1981. The samples were analysed for total particulate carbon concentration and isotopic composition (13C/12C) by mass spectrometry. Observed concentrations were found high compared to values reported for temperate regions. Fine particulate carbon in the submicrometersize range accounted for 50 to 80% of the reported concentrations. At Lamto, both particulate carbon concentrations and isotopic ratios exhibit a large temporal variability which is shown to reflect the diversity of sources and their seasonal evolution. Natural emissions from the equatorial forest during the wet season, and biomass burning during the dry season, appear to be the major sources. The latter, though active during only a third of the year, is, on an annual basis, the most important source. Based on the data obtained at Lamto, an attempt has been made to estimate the flux of fine particulate carbon emitted from the tropical regions into the global troposphere. This flux, which is of the order of 20×1012 g C/yr, appears to be equivalent to the flux of fine particulate carbon emitted from industrial sources. These results suggest that the tropospheric burden of fine particulate carbon in lowlatitude regions is dominated by the long-range transport of carbonaceous aerosols originating from the Tropics.  相似文献   

11.
In December 2015, China joined 190 plus nations at Paris in committing to the goal of limiting the rise in global average temperature to ‘well below’ 2°C. Carbon budget analysis indicates that goal will require not only that the European Union and US reduce their emissions by greater than 80% by 2050, but that China at least comes close to doing so as well, if any budget is to be left over for the rest of the world (RoW). Given that RoW emissions are, and will come from, low-income and emerging nations, China’s emission reduction potential is of no small consequence. In this paper, we use the Kaya identity to back out changes in the drivers of CO2 emissions, including gross domestic product (GDP), energy intensity (E/GDP) and the carbon content of energy (C/E), the latter two calculated to be consistent with China’s long-term GDP growth rate forecasts and specified 2050 CO2 emission reduction targets. Our results suggest that even achieving China’s highly optimistic renewable energy targets will be very far from sufficient to reduce China’s CO2 emissions from 9.1?Gt it emitted in 2015 to much below 3?Gt by 2050. Even reducing its emissions to 5?Gt will be challenging, yet this falls far short of what is needed if the world is to meet its ‘well below’ 2°C commitment.

Key policy insights

  • Under the Paris Agreement there is great pressure on China to very substantially reduce its emissions by 2050.

  • While China has attached great importance to renewables and nuclear energy development, even achieving the most optimistic targets would not be sufficient to reduce China’s emissions from 9.1?Gt in 2015 to much below 3?Gt by 2050.

  • China’s emission reduction potential falls far short of what is needed if the world is to meet its Paris ‘well below’ 2°C commitment, even if the EU and US reduce their emissions to zero by 2050.

  • Emission cuts consistent with the Paris Agreement will require that China and the world give much greater weight to advancing research and development of scalable low-, zero- and negative-carbon sources and technologies.

  相似文献   

12.

The expected growth in the demand for passenger and freight services exacerbates the challenges of reducing transport GHG emissions, especially as commercial low-carbon alternatives to petroleum fuels are limited for shipping, air and long-distance road travel. Biofuels can offer a pathway to significantly reduce emissions from these sectors, as they can easily substitute for conventional liquid fuels in internal combustion engines. In this paper, we assess the potential of bioenergy to reduce transport GHG emissions through an analysis leveraging various integrated assessment models and scenarios, as part of the 33rd Energy Modeling Forum study (EMF-33). We find that bioenergy can contribute a significant, albeit not dominant, proportion of energy supply to the future transport sector: in scenarios aiming to keep the temperature increase below 2 °C by the end of the twenty-first century, models project that in 2100 bioenergy can provide on average 42 EJ/yr (ranging from 5 to 85 EJ/yr) for transport (compared to 3.7 EJ in 2018), mainly through lignocellulosic fuels. This makes up 9–62% of final transport energy use. Only a small amount of bioenergy is projected to be used in transport through electricity and hydrogen pathways, with a larger role for biofuels in road passenger transport than in freight. The association of carbon capture and storage (CCS) with bioenergy technologies (BECCS) is a key determinant in the role of biofuels in transport, because of the competition for biomass feedstock to provide other final energy carriers along with carbon removal. Among models that consider CCS in the biofuel conversion process the average market share of biofuels is 21% in 2100 (ranging from 2 to 44%), compared to 10% (0–30%) for models that do not. Cumulative direct emissions from the transport sector account for half of the emission budget (from 306 to 776 out of 1,000 GtCO2). However, the carbon intensity of transport decreases as much as other energy sectors in 2100 when accounting for process emissions, including carbon removal from BECCS. Lignocellulosic fuels become more attractive for transport decarbonization if BECCS is not feasible for any energy sectors. Since global transport service demand increases and biomass supply is limited, its allocation to and within the transport sector is uncertain and sensitive to assumptions about political as well as technological and socioeconomic factors.

  相似文献   

13.
We developed a volume-to-biomass method based on age groups representative of forest development stages to estimate live tree biomass, C, and biomass and C accumulation rates of Chinas forests between 1973 and 1993. The data were from plot-level forest inventory, national-level inventory statistics, and ecological site studies specified to estimate biomass in different tree components. Our results indicate that carbon storage in Chinas forests was 4.34 Pg C in the early 1990s, an increase of 13% since the early 1970s. The annual forest C sequestration rate from the late 1980s to early 1990s was 0.068 Pg C/yr and approximately four- to five-times higher than in the 1970s and 1980s. The large C sink in Chinas forests in the early 1990s was likely related to age structure changes that had developed to more productive stages, a consequence of reforestation and afforestation programs from the 1960s. The results were compared with other C store estimates, which were based on the same inventory data. Various methods can produce estimates that differ in the direction of C flux as well as its magnitude. Separating age groups with the volume–biomass method could cause a 27% difference in estimated carbon pools but an 89% difference in C sequestration rates whereas the biomass density method would provide an estimate that differs by 65% in the C pools.  相似文献   

14.
We developed a volume-to-biomass method based on age groups representative of forest development stages to estimate live tree biomass, C, and biomass and C accumulation rates of Chinas forests between 1973 and 1993. The data were from plot-level forest inventory, national-level inventory statistics, and ecological site studies specified to estimate biomass in different tree components. Our results indicate that carbon storage in Chinas forests was 4.34 Pg C in the early 1990s, an increase of 13% since the early 1970s. The annual forest C sequestration rate from the late 1980s to early 1990s was 0.068 Pg C/yr and approximately four- to five-times higher than in the 1970s and 1980s. The large C sink in Chinas forests in the early 1990s was likely related to age structure changes that had developed to more productive stages, a consequence of reforestation and afforestation programs from the 1960s. The results were compared with other C store estimates, which were based on the same inventory data. Various methods can produce estimates that differ in the direction of C flux as well as its magnitude. Separating age groups with the volume–biomass method could cause a 27% difference in estimated carbon pools but an 89% difference in C sequestration rates whereas the biomass density method would provide an estimate that differs by 65% in the C pools.  相似文献   

15.
Greenhouse gas abatement policies will increase the demand for renewable sources of energy, including bioenergy. In combination with a global growing demand for food, this could lead to a food-fuel competition for bio-productive land. Proponents of bioenergy have suggested that energy crop plantations may be established on less productive land as a way of avoiding this potential food-fuel competition. However, many of these suggestions have been made without any underlying economic analysis. In this paper, we develop a long-term economic optimization model (LUCEA) of the U.S. agricultural and energy system to analyze this possible competition for land and to examine the link between carbon prices, the energy system dynamics and the effect of the land competition on food prices. Our results indicate that bioenergy plantations will be competitive on cropland already at carbon taxes about US $20/ton C. As the carbon tax increases, food prices more than double compared to the reference scenario in which there is no climate policy. Further, bioenergy plantations appropriate significant areas of both cropland and grazing land. In model runs where we have limited the amount of grazing land that can be used for bioenergy to what many analysts consider the upper limit, most of the bioenergy plantations are established on cropland. Under the assumption that more grazing land can be used, large areas of bioenergy plantations are established on grazing land, despite the fact that yields are assumed to be much lower (less than half) than on crop land. It should be noted that this allocation on grazing land takes place as a result of a competition between food and bioenergy production and not because of lack of it. The estimated increase in food prices is largely unaffected by how much grazing land can be used for bioenergy production.  相似文献   

16.
Hydrogen is named as possible energy carrier for future energy systems. However, the impact of large-scale hydrogen use on the atmosphere is uncertain. Application of hydrogen in clean fuel cells reduces emissions of air pollutants, but emissions from hydrogen production and leakages of molecular hydrogen could influence atmospheric chemistry. This paper combines a global energy system model and a global atmospheric model to explore the range of impacts of hydrogen on atmospheric chemistry. We found that emissions of molecular hydrogen may range from 0.2 up to 10% (or 25-167 Tg hydrogen/yr) for a global hydrogen energy system. The lower end of this range would in fact be equal to current emissions from fossil fuel combustion. Hydrogen energy use leads to a clear decrease in emissions of carbon monoxide, nitrogen oxides and sulphur dioxide, but large-scale hydrogen production from coal may lead to net increase in emissions of nitrous oxide and volatile organic compound. Compared to a reference scenario, this would lead to positive impacts on surface concentrations of carbon monoxide, nitrogen oxides and ozone. However, if hydrogen leakage would not be minimised it leads to an increase in methane lifetimes and a decrease in stratospheric ozone concentrations.  相似文献   

17.
Sea level rise (SLR) is among the climate-change-related problems of greatest concern, threatening the lives and property of coastal residents and generating far-reaching economic and ecological impacts. We project that SLR will lead to an increase in the rate of new housing construction to replace destroyed structures, impact global wood products supply and demand conditions, and cause changes in global forest sector carbon mitigation potential. Findings indicate that 71 million new units will be built by 2050 to accommodate the SLR-affected global population. More than two-thirds of these new units are projected to be in Asia. The estimated extra wood products needed to build these new residential units is 1,659 million m3, assuming that all these structures would be built mainly with wood, representing a 4 % increase in total wood consumption, compared to projected reference level global wood products consumption. Increased timber removals to meet this higher construction wood demand (alternative scenario) is shown to deplete global forest carbon by 2 % by 2050 compared to the reference scenario. However, all such projected declines in forest biomass carbon could be more than offset by increased carbon sequestration in harvested wood products, avoided emissions due to substitution of wood for non-wood materials in construction, and biomass regrowth on forestland by 2050, with an estimated net emissions reduction benefit of 0.47 tCO2e/tCO2e of extra wood used in SLR-related new houses over 30 years. The global net emissions reduction benefit increased to 2.13 tCO2e/tCO2e of extra wood when price-induced changes in forest land area were included.  相似文献   

18.
Deforestation, the second largest source of anthropogenic greenhouse gas emissions, is largely driven by expanding forestry and agriculture. However, despite agricultural expansion being increasingly driven by foreign demand, the links between deforestation and foreign demand for agricultural commodities have only been partially mapped. Here we present a pan-tropical quantification of carbon emissions from deforestation associated with the expansion of agriculture and forest plantations, and trace embodied emissions through global supply chains to consumers. We find that in the period 2010–2014, expansion of agriculture and tree plantations into forests across the tropics was associated with net emissions of approximately 2.6 gigatonnes carbon dioxide per year. Cattle and oilseed products account for over half of these emissions. Europe and China are major importers, and for many developed countries, deforestation emissions embodied in imports rival or exceed emissions from domestic agriculture. Depending on the trade model used, 29–39% of deforestation-related emissions were driven by international trade. This is substantially higher than the share of fossil carbon emissions embodied in trade, indicating that efforts to reduce greenhouse gas emissions from land-use change need to consider the role of international demand in driving deforestation. Additionally, we find that deforestation emissions are similar to, or larger than, other emissions in the carbon footprint of key forest-risk commodities. Similarly, deforestation emissions constitute a substantial share (˜15%) of the total carbon footprint of food consumption in EU countries. This highlights the need for consumption-based accounts to include emissions from deforestation, and for the implementation of policy measures that cross these international supply-chains if deforestation emissions are to be effectively reduced.  相似文献   

19.
Carbon sequestration through ecological restoration programs is an increasingly important option to reduce the rise of atmospheric carbon dioxide concentration. China’s Grain for Green Program (GGP) is likely the largest centrally organized land-use change program in human history and yet its carbon sequestration benefit has yet to be systematically assessed. Here we used seven empirical/statistical equations of forest biomass carbon sequestration and five soil carbon change models to estimate the total and decadal carbon sequestration potentials of the GGP during 1999–2050, including changes in four carbon pools: aboveground biomass, roots, forest floor and soil organic carbon. The results showed that the total carbon stock in the GGP-affected areas was 682 Tg C in 2010 and the accumulative carbon sink estimates induced by the GGP would be 1697, 2635, 3438 and 4115 Tg C for 2020, 2030, 2040 and 2050, respectively. Overall, the carbon sequestration capacity of the GGP can offset about 3%–5% of China’s annual carbon emissions (calculated using 2010 emissions) and about 1% of the global carbon emissions. Afforestation by the GGP contributed about 25% of biomass carbon sinks in global carbon sequestration in 2000–2010. The results suggest that large-scale ecological restoration programs such as afforestation and reforestation could help to enhance global carbon sinks, which may shed new light on the carbon sequestration benefits of such programs in China and also in other regions.  相似文献   

20.
In order to study the effects of a change in the economic system on carbon balance at a national scale, a balance of the carbon influx and effluxes was prepared for forest ecosystems in Poland for 1988, and was repeated for 1990. The year 1988 was the first year of drastic economic changes (and severe crises) in Poland. Two entirely different approaches were used to estimate the carbon influx into a forest ecosystem. The forest inventory approach was based on data from conventional measurements of merchantable timber in forests, whereas the carbon flux and allocation approach was based on the estimate of net photosynthetic productivity of forest ecosystems to calculate the carbon influx. Results from both approaches were within the range 1.17 to 5.77t C/ha/yr which most likely defined lower and upper limits for the carbon influx into forest ecosystems in Poland. On the national scale, the carbon influx into Polish forest ecosystems was estimated by the forest inventory approach to be about 12.8 Mt C/yr. This result was similar for both years. Efflux of carbon from Polish forest ecosystems resulted almost entirely from the decay of logging residues. The efflux in 1990 (3.82 Mt C/yr) was about 26% lower than that in 1988. Storage of the carbon in Polish forest ecosystems (including an estimate of the carbon pool in forest soils) was 1.8% greater in 1990 (2518 Mt C) than in 1988, when it equalled 2473 Mt C.  相似文献   

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