Modeling Research On Land Use And Bioenergy Under The Integrated Assessment Framework Of Climate Change In China

The land is the carrier for everything on the planet, land use/land cover is thecore between ecosystem, human activity and climate change, the relations betweenthem are rather complex, it is the only way to take different opinions of all thedisciplines into consideration and use integrated assessment tool to analyses andevaluate comprehensively for solving the most complex global change problem. Inthis paper, After reviewing many literature about land use and biomass, we usePNNL’s integrated assessment modeling system,GCAM (Global ChangeAssessment model) and discuss numeral and spatial characteristics of land use andchange from2005to2095,and carbon emissions induced by land use and change；we also analyzes limiting concentration of greenhouse gases in the atmospherecarries implications for land use that are unavoidable and independent of theproduction of bioenergy crops, and various land use type change and spatialcharacteristics in the future;and further explore biomass development as a responseto agricultural economy、energy consumption and land use structure； and alsoanalyze the mechanism of carbon tax and low carbon technology for addressingclimate change;and also make further research into land resources optimizationutilization and provide policy and suggestion to address climate change for countryand regions. Main conclusions are as follows：(1) Land use and changes is quite a complex process which is driven by manyfactors such as natural, historical and economic factors, its results are change ofnumeral and spatial characteristics of land use and change, the land allocationscheme used by comprehensive appraisal framework of climate change is based onmaximizing profit at each location, The result shows:The demand for agroforestryproducts and livestock products will increase with the improvement developmentof population and standard living in the reference scenario in the future, peopletends to consume more livestock products with the improvement of living standard,but the prices of global agricultural products change at a modest rate. Whenbioenergy crops are introduced in2020, different land use type suffers an abruptchange, After2020crop land decreases;managed forest slightly rises;managedpasture reached its height about2050and then sharply goes down；unmanagedforest and unmanaged pasture somewhat decline;fallow land stays the same；planting areas of rice and wheat downtrend basically, but planting area of cornshow the peak in2050and has remained fundamentally unchanged after that；bioenergy crops land rapidly goes up in the simulation stage due to the growth ofenergy demand. In the policy scenario, the tax is applied to all carbon—fossil fuel, industrial, and land-use change carbon emissions,and the benefit of carbon storageand sequestration is evaluated in the terrestrial ecosystem, landowner would likeincrease carbon storage including soil and vegetation for more profit； carbonstorage implies that the unmanaged ecosystems will increase in value with thevalue of carbon, the higher tax, the more value of carbon assimilation;landallocation is the result of a combination of many factors together such as carbontax policy、energy market、agricultural products market and land productivity.Compared with the reference scenario, the price of global agricultural productsrapidly increases;planting area entirely grows upward, fallow land sharply goesdown;all of the managed forest and managed pasture will decrease due toimprovement of cutting cost, other land expands to lower the area of unmanagedpasture land、grass land and shrub land；unmanaged forest sharply goes up with anincrease of carbon price;The increase in the price of agricultural products promptthe increase of planting area of rice、wheat and corn, and their areas reach theheight in the year2050; In contrast, Carbon price is reduced by low carbontechnology CCS and unmanaged ecosystem compete successfully in a good manyland uses.(2)Human activities,through land use, land-use change and forestry (LULUCF)activities, affect changes in carbon stocks between the carbon pools of theterrestrial ecosystem and between the terrestrial ecosystem and the atmosphere,impacts on land-use and land-cover change, and carbon emissions from land usechange are mainly induced by transformation between different land use type. Inthis paper, we simulate carbon emissions from land use change by GCAM in theCO2-control scenario, the result shows:compared with the BAU, in the policyscenario carbon emissions decrease relative the reference scenario, and carbonemissions are negative in the total terrestrial ecosystems after2050. Whenbioenergy crops are introduced in2020, the land use change emissions are abrupt；in contrast, the emissions in the lower CO2-control concentration are much lessthan that in the higher CO2-control concentration, this further indicates climatepolicy play an important role on emissions mitigation; CO2capture and storage(CCS) has little effect on emission mitigation from land use change.In contrast,emissions with CO2capture and storage (CCS) are slightly more than that withoutCCS in the early period, but carbon sink is a bit less than that without CO2captureand storage (CCS) after2050.(3) Biomass development is the better way for solving energy crisis andenvironment problems and for mitigating climate change. This studies simulatesupply and demand of second bioenergy by GCAM in China, the results shows： the availability of biomass supply is the result of a combination of many factorstogether such as biomass energy demand、carbon tax policy and CCS, the highercarbon tax would result in more production of biomass energy；residue biomass andMunicipal Solid Waste (MSW) originate from land products, but they occupy nomore land and could not allocate land as a second bioenergy, residue biomass ismainly distributed in AEZ10、AEZ11and AEZ12, the higher bioenergy price wouldresult in higher production of residue biomass in the future, but the distributionwould not basically change;we have assumed two bioenergy crops such asswitchgrass and willow that are representative for those that can be grownadvantageously in different AEZ of China on the basis of their biologicalcharacteristic, These choices do not imply that other similar crops would not alsobe grown, and these crops and modeling results should be interpreted as beingrepresentative of similar crops or potential bioenergy crop available as well,bioenergy crop land is based on maximizing profit that is determined by jointaction of bioenergy price、carbon tax and terrestrial sink, but much higher carbontax would decline the expansion of bioenergy crops land； bioenergy crop landwith climate policy becomes much larger than that without climate policy in thesame step, bioenergy land area increases in both CCS scenario and NOCCSscenario;This particular technology combination result in more bioenergy landwith CCS scenario because bioenergy obtains its carbon from the atmosphere andif that carbon were to be captured and isolated permanently from the atmospherethe net effect of the two technologies would be to produce energy with negativeCO2emissions,but bioenergy is just energy substitution in the NOCCS scenario.Biomass crops are mainly distributed in AEZ11and AEZ12and expand with anincrease of carbon tax. The higher bioenergy price would result in much morepotential production of MSW from food and wood processing residues, the trend ofpotential production that is determined by GDP and population which areexogenous variable in different scenario is basically consistent.(4)Bioenergy development has an impact on farm-product prices、 energyconsumption structure、land use structure、ecological environment、water resourcesand biodiversity at different degree, in this paper we just consider the“second-generation” bioenergy and simulate their effects on such a large timescale. the result shows：Agricultural Commodity Market: bioenergy market is the linkage betweenagricultural market and energy market, Fluctuations in the price of energy wouldlead to the corresponding change of planting areas、crop prices and land use; theprice could show the correlation between energy market and agricultural market, the correlation between them is very strong while we make great efforts to developbioenergy since2020in the policy scenario；in the reference scenario fluctuationsin the price of bioenergy and crop is small and there is a negative correlationbetween bioenergy price and crop prices；in the climate policy scenario highercarbon price would lead to higher bioenergy price and food price and the trend ofcarbon price accords with the price of bioenergy and crop; CCS could reduceincrease in the price of crop to a certain extent, the changes in crop prices withoutCCS show variations higher than that of crop prices with CCS up to the samelimiting concentration.Energy consumption structure: Both implementation of mitigation climatechange policy such as energy-saving and emission-reduction、carbon tax and CCStechnology and development of second-generation bioenergy would reduce cost ofbioenergy production, and also increase its relative profit. Bioenergy that isdeveloped in the world has great influence on energy consumption structure inChina. In the reference scenario the total energy consumption goes up in thiscentury, the proportion of fossil energy consumption in primary energyconsumption is about88%which is the average from2005to2095, and theproportion of bioenergy consumption in primary energy consumption is roughly4%; in the policy scenario the total energy consumption declines in this centuryand reaches the height about2050, decrease in the proportion of fossil energyconsumption, increase in the proportion of bioenergy energy consumption. Theproportion of bioenergy increases with the implementation of strict limitingCO2-control in a carbon constrained world.Land use structure： Expansion of bioenergy crops directly results in thedecrease of fallow land,and other lands such as forest、pasture、grassland and shrubland would change accordingly due to expansion of bioenergy crops.(5)Carbon market mechanism and low carbon technology such as CCS are animportant measure for mitigating climate change. Different limiting CO2concentrations show different carbon tax pathes. Carbon tax would reach a prettyprice in an extremely limiting CO2concentration the end of this century. Thecarbon price in the CCS450、CCS500、CCS550、NOCCS450、NOCCS500andNOCCS550target scenario is364、204、118、616、327and166yuan in2005RMBin the year2020. the carbon price in2020is about39times higher than in2095inall scenarios. In the same scenario group higher carbon tax would result in lowerCO2concentration. carbon tax without CCS is significantly higher than with CCSin the same step if obtaining the same limiting concentration. the trend of reductioncost is similar to that of carbon tax in all the scenarios. The proportion of reduction cost in GDP in the year2020in the CCS450、CCS500、CCS550、NOCCS450、NOCCS500and NOCCS550target scenario is about0.13%、0.05%、0.02%、0.34%、0.11%and0.04%. the reduction cost without CCS for the450ppm、500ppm and550ppm CO2limit is1.8、1.7and1.7times than with CCS, CCS technology willplay a positive role in mitigation of climate change.(6) sensitivity analysis: Crop productivity growth could decrease CO2concentration in the atmosphere；the results for bioenergy crops land,crop land,forest and agricultural prices are sensitive to crop productivity growth, and Cropproductivity growth could decline agricultural prices to a certain extent； policyscenario result for bioenergy price is not sensitive to crop productivity growth； intwo scenario groups productivity growth could improve the production ofbioenergy crops,but the result for residue biomas is almost sensitive； On such alarge time scale crop productivity growth could decrease fossil energyconsumption.