Regional Analysis

Impacts of CO2 Mandates for New Cars in the European Union

CO₂ emissions mandates for new light-duty passenger vehicles have recently been adopted in the European Union (EU), which require steady reductions to 95 g CO₂/km in 2021. Using a computable general equilibrium (CGE) model, we analyze the impact of the mandates on oil demand, CO₂ emissions, and economic welfare, and compare the results to an emission trading scenario that achieves identical emissions reductions. We find that the mandates lower oil expenditures by about €6 billion, but at a net added cost of €12 billion in 2020. Emissions from transport are about 50MtCO₂ lower with the vehicle emission standards, but with the economy-wide emission trading, lower emissions in transport allow an equal increase in emissions elsewhere in the economy. We estimate that tightening CO₂ standards further after 2020 would cost the EU economy an additional €24–63 billion in 2025 compared with achieving the same reductions with an economy-wide emission trading system.

Impacts of the Minamata Convention on Mercury Emissions and Global Deposition from Coal-Fired Power Generation in Asia

We explore implications of the United Nations Minamata Convention on Mercury for emissions from Asian coal-fired power generation, and resulting changes to deposition worldwide by 2050. We use engineering analysis, document analysis, and interviews to construct plausible technology scenarios consistent with the Convention. We translate these scenarios into emissions projections for 2050, and use the GEOS-Chem model to calculate global mercury deposition. Where technology requirements in the Convention are flexibly defined, under a global energy and development scenario that relies heavily on coal, we project ∼90 and 150 Mg·y^–1 of avoided power sector emissions for China and India, respectively, in 2050, compared to a scenario in which only current technologies are used. Benefits of this avoided emissions growth are primarily captured regionally, with projected changes in annual average gross deposition over China and India ∼2 and 13 μg·m^–2 lower, respectively, than the current technology case. Stricter, but technologically feasible, mercury control requirements in both countries could lead to a combined additional 170 Mg·y^–1 avoided emissions. Assuming only current technologies but a global transition away from coal avoids 6% and 36% more emissions than this strict technology scenario under heavy coal use for China and India, respectively.

Is Current Irrigation Sustainable in the United States? An Integrated Assessment of Climate Change Impact on Water Resources and Irrigated Crop Yields

While the impact of climate change on crop yields has been extensively studied, the quantification of water shortages on irrigated crop yields has been regarded as more challenging due to the complexity of the water resources management system. To investigate this issue, we integrate a crop yield reduction module and a water resources model into the MIT Integrated Global System Modeling (IGSM) framework, an integrated assessment model that links a model of the global economy to an Earth system model. While accounting for uncertainty in climate change, we assess the effects of climate and socio-economic changes on the competition for water resources between industrial, energy, domestic and irrigation; the implications for water availability for irrigation; and the subsequent impacts on crop yields in the US by 2050. We find that climate and socio-economic changes will increase water shortages and strongly reduce irrigated crop yields in specific regions (mostly in the Southwest), or for specific crops (i.e. cotton and forage). While the most affected regions are usually not major crop growers, the heterogeneous response of crop yield to global change and water stress suggests that some level of adaptation can be expected, such as the relocation of cropland area to regions where irrigation is more sustainable. Finally, GHG mitigation has the potential to alleviate the effect of water stress on irrigated crop yields—enough to offset the reduced CO2 fertilization effect compared to an unconstrained GHG emission scenario.

Land carbon sequestration within the conterminous United States: Regional- and state-level analyses

A 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.

Limited trading of emissions permits as a climate cooperation mechanism? US–China and EU–China examples

Recent multilateral climate negotiations have underlined the importance of international cooperation and the need for support from developed to developing countries to address climate change. This raises the question of whether carbon market linkages could be used as a cooperation mechanism. Policy discussions surrounding such linkages have indicated that, should they operate, a limit would be set on the amount of carbon permits that could be imported by developed regions from developing countries. This paper analyzes the impact of limited carbon trading between an ETS in the EU or the US and a carbon market covering Chinese electricity and energy intensive sectors using a global economy-wide model. We find that the limit results in different carbon prices between China and Europe or the US. Although the impact on low-carbon technologies in China is moderate, global emission reductions are deeper than in the absence of international trading due to reduced carbon leakage. If China captures the rents associated with limited permit trading, we show that it is possible to find a limit threshold that makes both regions better off relative to carbon markets operating in isolation.

Modeling Regional Transportation Demand in China and the Impacts of a National Carbon Policy

China's climate and energy policy commitments are stated at the national level, but they may have uneven impacts on the country's regionally heterogeneous transport system. This work quantifies the expected provincial-level response of freight transport to an economywide policy targeting reductions in carbon emissions intensity. The analysis applies the China Regional Energy Model, a multisector, static, global, computable general equilibrium (CGE) model representing 30 individual provinces with physical accounts of energy and greenhouse gas emissions. The structure of road and nonroad freight (and passenger) sectors, the preparation of transport activity data, and a policy similar to announced goals that specify a 17% reduction in the carbon dioxide emissions intensity of gross domestic product are described. In the national aggregate and in most provinces, the road freight sector is most affected by the emissions intensity cap. The road freight sector contributes 24%—versus 18% from nonroad freight and 51% from nontransport sectors—of a 5.1% reduction in national refined oil demand. Significant regional differences are found in the impacts of a national-level, economywide policy. Steep reductions in freight activity occur in some of the poorest provinces, partly because they offer low-cost abatement opportunities, and the resulting adjustments across the economy affect transport demand. This research contributes a new tool capable of capturing the transport impact of sector- and province-specific policies in detail and providing a rigorous foundation for future dynamic CGE analyses. Potential impacts of energy and climate policy on regional transport systems are important inputs to policy and infrastructure investment decisions at the central and local levels.

Modelling the potential for wind energy integration on China's coal-heavy electricity grid

Expanding the use of wind energy for electricity generation forms an integral part of China’s efforts to address degraded air quality and climate change. However, the integration of wind energy into China’s coal-heavy electricity system presents significant challenges owing to wind’s variability and the grid’s system-wide inflexibilities. Here we develop a model to predict how much wind energy can be generated and integrated into China’s electricity mix, and estimate a potential production of 2.6 petawatt-hours (PWh) per year in 2030. Although this represents 26% of total projected electricity demand, it is only 10% of the total estimated physical potential of wind resources in the country. Increasing the operational flexibility of China’s coal fleet would allow wind to deliver nearly three-quarters of China’s target of producing 20% of primary energy from non-fossil sources by 2030.

China, the world’s largest energy consumer and greenhouse gas emitter, has made deploying wind-generated electricity a cornerstone of long-term plans to mitigate climate change, air pollution and other energy-related environmental impacts. Following rapid expansion in recent years, especially in remote, less populous areas, wind has faced significant challenges integrating into the coal-heavy power grid owing to its fundamental operational differences compared to conventional energy sources. We present the first assessment of China’s wind energy potential and its regional distribution that incorporates an operational model of the grid and undertakes systematic exploration of key uncertainties.

Natural Gas Pricing Reform in China: Getting Closer to a Market System?

Recent policy in China targets an increase in the contribution of natural gas to the nation’s energy supply. Historically, China’s natural gas prices have been highly regulated with a goal to protect consumers. The old pricing regime failed to provide enough incentives for natural gas suppliers, which often resulted in natural gas shortages. A new gas pricing reform was tested in Guangdong and Guangxi provinces in 2011 and was introduced nationwide in 2013. The reform is aimed at creating a more market based pricing mechanism. We show that substantial progress toward better predictability and transparency of prices has been made. China’s prices are now more connected with international fuel oil and liquid petroleum gas prices. The government’s approach for temporary two tier pricing when some volumes are still traded at old prices reduced potential opposition during the new regime implementation. Some limitations created by the natural gas pricing remain: it created biased incentives for producers and favors large natural gas suppliers. The pricing reform at its current stage falls short of establishing a complete market mechanism driven by an interaction of supply and demand of natural gas in China.

Origin of oxidized mercury in the summertime free troposphere over the southeastern U.S.

We collected mercury observations as part of the Nitrogen, Oxidants, Mercury, and Aerosol Distributions, Sources, and Sinks (NOMADSS) aircraft campaign over the southeastern US between 1 June and 15 July 2013. We use the GEOS-Chem chemical transport model to interpret these observations and place new constraints on bromine radical initiated mercury oxidation chemistry in the free troposphere. We find that the model reproduces the observed mean concentration of total atmospheric mercury (THg) (observations: 1.49 ± 0.16"¯ng m⁻³, model: 1.51 ± 0.08"¯ng m⁻³), as well as the vertical profile of THg. The majority (65"¯%) of observations of oxidized mercury (Hg(II)) were below the instrument's detection limit (detection limit per flight: 58–228"¯pg m⁻³), consistent with model-calculated Hg(II) concentrations of 0–196"¯pg m⁻³. However, for observations above the detection limit we find that modeled Hg(II) concentrations are a factor of 3 too low (observations: 212 ± 112"¯pg m⁻³, model: 67 ± 44"¯pg m⁻³). The highest Hg(II) concentrations, 300–680"¯pg m⁻³, were observed in dry (RH"¯ < "¯35"¯%) and clean air masses during two flights over Texas at 5–7"¯km altitude and off the North Carolina coast at 1–3"¯km. The GEOS-Chem model, back trajectories and observed chemical tracers for these air masses indicate subsidence and transport from the upper and middle troposphere of the subtropical anticyclones, where fast oxidation of elemental mercury (Hg(0)) to Hg(II) and lack of Hg(II) removal lead to efficient accumulation of Hg(II). We hypothesize that the most likely explanation for the model bias is a systematic underestimate of the Hg(0) + Br reaction rate. We find that sensitivity simulations with tripled bromine radical concentrations or a faster oxidation rate constant for Hg(0) + Br, result in 1.5–2 times higher modeled Hg(II) concentrations and improved agreement with the observations. The modeled tropospheric lifetime of Hg(0) against oxidation to Hg(II) decreases from 5"¯months in the base simulation to 2.8–1.2"¯months in our sensitivity simulations. In order to maintain the modeled global burden of THg, we need to increase the in-cloud reduction of Hg(II), thus leading to faster chemical cycling between Hg(0) and Hg(II). Observations and model results for the NOMADSS campaign suggest that the subtropical anticyclones are significant global sources of Hg(II).

Pathways to Mexico's climate change mitigation targets: A multi-model analysis

Mexico’s climate policy sets ambitious national greenhouse gas (GHG) emission reduction targets—30% versus a business-as-usual baseline by 2020, 50% versus 2000 by 2050. However, these goals are at odds with recent energy and emission trends in the country. Both energy use and GHG emissions in Mexico have grown substantially over the last two decades. We investigate how Mexico might reverse current trends and reach its mitigation targets by exploring results from energy system and economic models involved in the CLIMACAP-LAMP project. To meet Mexico’s emission reduction targets, all modeling groups agree that decarbonization of electricity is needed, along with changes in the transport sector, either to more efficient vehicles or a combination of more efficient vehicles and lower carbon fuels. These measures reduce GHG emissions as well as emissions of other air pollutants. The models find different energy supply pathways, with some solutions based on renewable energy and others relying on biomass or fossil fuels with carbon capture and storage. The economy-wide costs of deep mitigation could range from 2% to 4% of GDP in 2030, and from 7% to 15% of GDP in 2050. Our results suggest that Mexico has some flexibility in designing deep mitigation strategies, and that technological options could allow Mexico to achieve its emission reduction targets, albeit at a cost to the country.

MIT Global Change

Regional Analysis

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