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John M.
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John M.
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ArticleProbabilistic forecast for twenty-first-century climate based on uncertainties in emissions (without policy) and climate parameters(American Meteorological Society, 2009-10-01) Sokolov, Andrei P. ; Stone, P. H. ; Forest, C. E. ; Prinn, Ronald G. ; Sarofim, Marcus C. ; Webster, M. ; Paltsev, Sergey ; Schlosser, C. Adam ; Kicklighter, David W. ; Dutkiewicz, Stephanie ; Reilly, John M. ; Wang, C. ; Felzer, Benjamin S. ; Melillo, Jerry M. ; Jacoby, Henry D.The Massachusetts Institute of Technology (MIT) Integrated Global System Model is used to make probabilistic projections of climate change from 1861 to 2100. Since the model’s first projections were published in 2003, substantial improvements have been made to the model, and improved estimates of the probability distributions of uncertain input parameters have become available. The new projections are considerably warmer than the 2003 projections; for example, the median surface warming in 2091–2100 is 5.1°C compared to 2.4°C in the earlier study. Many changes contribute to the stronger warming; among the more important ones are taking into account the cooling in the second half of the twentieth century due to volcanic eruptions for input parameter estimation and a more sophisticated method for projecting gross domestic product (GDP) growth, which eliminated many low-emission scenarios. However, if recently published data, suggesting stronger twentieth-century ocean warming, are used to determine the input climate parameters, the median projected warming at the end of the twenty-first century is only 4.1°C. Nevertheless, all ensembles of the simulations discussed here produce a much smaller probability of warming less than 2.4°C than implied by the lower bound of the Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report (AR4) projected likely range for the A1FI scenario, which has forcing very similar to the median projection in this study. The probability distribution for the surface warming produced by this analysis is more symmetric than the distribution assumed by the IPCC because of a different feedback between the climate and the carbon cycle, resulting from the inclusion in this model of the carbon–nitrogen interaction in the terrestrial ecosystem.
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ArticlePotential influence of climate-induced vegetation shifts on future land use and associated land carbon fluxes in Northern Eurasia(IOP Publishing, 2014-03-21) Kicklighter, David W. ; Cai, Y. ; Zhuang, Qianlai ; Parfenova, E. I. ; Paltsev, Sergey ; Sokolov, Andrei P. ; Melillo, Jerry M. ; Reilly, John M. ; Tchebakova, Nadja M. ; Lu, X.Climate change will alter ecosystem metabolism and may lead to a redistribution of vegetation and changes in fire regimes in Northern Eurasia over the 21st century. Land management decisions will interact with these climate-driven changes to reshape the region's landscape. Here we present an assessment of the potential consequences of climate change on land use and associated land carbon sink activity for Northern Eurasia in the context of climate-induced vegetation shifts. Under a 'business-as-usual' scenario, climate-induced vegetation shifts allow expansion of areas devoted to food crop production (15%) and pastures (39%) over the 21st century. Under a climate stabilization scenario, climate-induced vegetation shifts permit expansion of areas devoted to cellulosic biofuel production (25%) and pastures (21%), but reduce the expansion of areas devoted to food crop production by 10%. In both climate scenarios, vegetation shifts further reduce the areas devoted to timber production by 6–8% over this same time period. Fire associated with climate-induced vegetation shifts causes the region to become more of a carbon source than if no vegetation shifts occur. Consideration of the interactions between climate-induced vegetation shifts and human activities through a modeling framework has provided clues to how humans may be able to adapt to a changing world and identified the trade-offs, including unintended consequences, associated with proposed climate/energy policies.
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ArticleCorrigendum(American Meteorological Society, 2010-04-15) Sokolov, Andrei P. ; Stone, P. H. ; Forest, C. E. ; Prinn, Ronald G. ; Sarofim, Marcus C. ; Webster, M. ; Paltsev, Sergey ; Schlosser, C. Adam ; Kicklighter, David W. ; Dutkiewicz, Stephanie ; Reilly, John M. ; Wang, C. ; Felzer, Benjamin S. ; Melillo, Jerry M. ; Jacoby, Henry D.Corrigendum: Sokolov, A., and Coauthors, 2009: Probabilistic forecast for twenty-first-century climate based on uncertainties in emissions (without policy) and climate parameters. J. Climate, 22, 5175–5204.
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PreprintOptimizing resource use efficiencies in the food-energy-water nexus for sustainable agriculture : from conceptual model to decision support system( 2018-04) Tian, Hanqin ; Lu, Chaoqun ; Pan, Shufen ; Yang, Jia ; Miao, Ruiqing ; Ren, Wen ; Yu, Qiang ; Fu, Bojie ; Jin, Fei-Fei ; Lu, Yonglong ; Melillo, Jerry M. ; Ouyang, Zhiyun ; Palm, Cheryl A. ; Reilly, John M.Increased natural and anthropogenic stresses have threatened the Earth’s ability to meet growing human demands of food, energy and water (FEW) in a sustainable way. Although much progress has been made in the provision of individual component of FEW, it remains unknown whether there is an optimized strategy to balance the FEW nexus as a whole, reduce air and water pollution, and mitigate climate change on national and global scales. Increasing FEW conflicts in the agroecosystems make it an urgent need to improve our understanding and quantification of how to balance resource investment and enhance resource use efficiencies in the FEW nexus. Therefore, we propose an integrated modeling system of the FEW nexus by coupling an ecosystem model, an economic model, and a regional climate model, aiming to mimic the interactions and feedbacks within the ecosystem-human-climate systems. The trade-offs between FEW benefit and economic cost in excess resource usage, environmental degradation, and climate consequences will be quantitatively assessed, which will serve as sustainability indicators for agricultural systems (including crop production, livestock and aquaculture). We anticipate that the development and implementation of such an integrated modeling platform across world’s regions could build capabilities in understanding the agriculture-centered FEW nexus and guiding policy and land management decision making for a sustainable future.
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ArticleLand carbon sequestration within the conterminous United States : regional- and state-level analyses(John Wiley & Sons, 2015-02-28) Lu, Xiaoliang ; Kicklighter, David W. ; Melillo, Jerry M. ; Reilly, John M. ; Xu, LiyiA quantitative understanding of the rate at which land ecosystems are sequestering or losing carbon at national-, regional-, and state-level scales is needed to develop policies to mitigate climate change. In this study, a new improved historical land use and land cover change data set is developed and combined with a process-based ecosystem model to estimate carbon sources and sinks in land ecosystems of the conterminous United States for the contemporary period of 2001–2005 and over the last three centuries. We estimate that land ecosystems in the conterminous United States sequestered 323 Tg C yr−1 at the beginning of the 21st century with forests accounting for 97% of this sink. This land carbon sink varied substantially across the conterminous United States, with the largest sinks occurring in the Southeast. Land sinks are large enough to completely compensate fossil fuel emissions in Maine and Mississippi, but nationally, carbon sinks compensate for only 20% of U.S. fossil fuel emissions. We find that regions that are currently large carbon sinks (e.g., Southeast) tend to have been large carbon sources over the longer historical period. Both the land use history and fate of harvested products can be important in determining a region's overall impact on the atmospheric carbon budget. While there are numerous options for reducing fossil fuels (e.g., increase efficiency and displacement by renewable resources), new land management opportunities for sequestering carbon need to be explored. Opportunities include reforestation and managing forest age structure. These opportunities will vary from state to state and over time across the United States.
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PreprintImpacts of ozone on trees and crops( 2007-07-05) Felzer, Benjamin S. ; Cronin, Timothy W. ; Reilly, John M. ; Melillo, Jerry M. ; Wang, XiaodongIn this review article, we explore how surface-level ozone affects trees and crops with special emphasis on consequences for productivity and carbon sequestration. Vegetation exposure to ozone reduces photosynthesis, growth, and other plant functions. Ozone formation in the atmosphere is a product of NOx that are also a source of nitrogen deposition. Reduced carbon sequestration of temperate forests resulting from ozone is likely offset by increased carbon sequestration from nitrogen fertilization. However, since fertilized croplands are generally not nitrogen-limited, capping ozone-polluting substances in the U.S., Europe, and China can reduce future crop yield loss substantially.
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PreprintFuture effects of ozone on carbon sequestration and climate change policy using a global biogeochemical model( 2004-10-29) Felzer, Benjamin S. ; Reilly, John M. ; Melillo, Jerry M. ; Kicklighter, David W. ; Sarofim, Marcus C. ; Wang, C. ; Prinn, Ronald G. ; Zhuang, QianlaiExposure of plants to ozone inhibits photosynthesis and therefore reduces vegetation production and carbon sequestration. The reduced carbon storage would then require further reductions in fossil fuel emissions to meet a given CO2 concentration target, thereby increasing the cost of meeting the target. Simulations with the Terrestrial Ecosystem Model (TEM) for the historical period (1860-1995) show the largest damages occur in the Southeast and Midwestern regions of the United States, eastern Europe, and eastern China. The largest reductions in carbon storage for the period 1950-1995, 41%, occur in eastern Europe. Scenarios for the 21st century developed with the MIT Integrated Global Systems Model (IGSM) lead to even greater negative effects on carbon storage in the future. In some regions, current land carbon sinks become carbon sources, and this change leads to carbon sequestration decreases of up to 0.4 Pg C yr-1 due to damage in some regional ozone hot spots. With a climate policy, failing to consider the effects of ozone damage on carbon sequestration would raise the global costs over the next century of stabilizing atmospheric concentrations of CO2 equivalents at 550 ppm by 6 to 21%. Because stabilization at 550 ppm will reduce emission of other gases that cause ozone, these additional benefits are estimated to be between 5 and 25% of the cost of the climate policy. Tropospheric ozone effects on terrestrial ecosystems thus produce a surprisingly large feedback in estimating climate policy costs that, heretofore, has not been included in cost estimates.
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ArticleFood benefit and climate warming potential of nitrogen fertilizer uses in China(IOP Publishing, 2012-10-31) Tian, Hanqin ; Lu, Chaoqun ; Melillo, Jerry M. ; Ren, Wei ; Huang, Yao ; Xu, Xiaofeng ; Liu, Mingliang ; Zhang, Chi ; Chen, Guangsheng ; Pan, Shufen ; Liu, Jiyuan ; Reilly, John M.Chemical nitrogen (N) fertilizer has long been used to help meet the increasing food demands in China, the top N fertilizer consumer in the world. Growing concerns have been raised on the impacts of N fertilizer uses on food security and climate change, which is lack of quantification. Here we use a carbon–nitrogen (C–N) coupled ecosystem model, to quantify the food benefit and climate consequence of agronomic N addition in China over the six decades from 1949 to 2008. Results show that N fertilizer-induced crop yield and soil C sequestration had reached their peaks, while nitrous oxide (N2O) emission continued rising as N was added. Since the early 2000s, stimulation of excessive N fertilizer uses to global climate warming through N2O emission was estimated to outweigh their climate benefit in increasing CO2 uptake. The net warming effect of N fertilizer uses, mainly centered in the North China Plain and the middle and lower reaches of Yangtze River Basin, with N2O emission completely counteracting or even exceeding, by more than a factor of 2, the CO2 sink. If we reduced the current N fertilizer level by 60% in 'over-fertilized' areas, N2O emission would substantially decrease without significantly influencing crop yield and soil C sequestration.
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PreprintGlobal economic effects of changes in crops, pasture, and forests due to changing climate, carbon dioxide, and ozone( 2006-01) Reilly, John M. ; Paltsev, Sergey ; Felzer, Benjamin S. ; Wang, X. ; Kicklighter, David W. ; Melillo, Jerry M. ; Prinn, Ronald G. ; Sarofim, Marcus C. ; Sokolov, Andrei P. ; Wang, C.Multiple environmental changes will have consequences for global vegetation. To the extent that crop yields and pasture and forest productivity are affected there can be important economic consequences. We examine the combined effects of changes in climate, increases in carbon dioxide, and changes in tropospheric ozone on crop, pasture, and forest lands and the consequences for the global and regional economies. We examine scenarios where there is limited or little effort to control these substances, and policy scenarios that limit emissions of CO2 and ozone precursors. We find the effects of climate and CO2 to be generally positive, and the effects of ozone to be very detrimental. Unless ozone is strongly controlled damage could offset CO2 and climate benefits. We find that resource allocation among sectors in the economy, and trade among countries, can strongly affect the estimate of economic effect in a country.