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The Paris Agreement formulates the goal of GHG neutrality in the second half of this century. Given that Nationally Determined Contributions are as yet insufficient, the question is through which policies can this goal be realized? Identifying policy pathways to ratchet up stringency is instrumental, but little guidance is available. We propose a policy sequencing framework and substantiate it using the cases of Germany and California. Its core elements are policy options to overcome barriers to stringency over time. Such sequencing can advance policy design and hopefully reconcile the controversy between first-best and second-best approaches.

Implementation of the European Union Renewable Energy Directive has triggered exponential growth in trading of pelletized wood fibers. Over 18 million tons of wood pellets were traded by EU member countries in 2018 of which a third were imported from the US. Concerns exist about negative impacts on US forests but systematic assessments are currently lacking. We assessed variability in fundamental attributes for timberland structure and carbon stocks within 123 procurement landscapes of wood pellet mills derived from over 38 thousand forest inventory plots in the eastern US from 2005 to 2017. We found more carbon stocks in live trees, but a fewer number of standing-dead trees, associated with the annual operation of large-scale wood pellet mills. In the US coastal southeast—where US pellet exports to the EU originate—there were fewer live and growing-stock trees and less carbon in soils with every year of milling operation than in the rest of the eastern US—which supplies the domestic market. Greater overlap of mills’ procurement areas exhibited discernible increments across selected carbon stocks. These trends likely reflect more intensive land management practices. Localized forest impacts associated with the wood pellet industry should continue to be monitored.

The Inflation Reduction Act (IRA) is regarded as the most prominent piece of federal climate legislation in the U.S. thus far. This paper investigates potential impacts of IRA on the power sector, which is the focus of many core IRA provisions. We summarize a multi-model comparison of IRA to identify robust findings and variation in power sector investments, emissions, and costs across 11 models of the U.S. energy system and electricity sector. Our results project that IRA incentives accelerate the deployment of low-emitting capacity, increasing average annual additions by up to 3.2 times current levels through 2035. CO 2 emissions reductions from electricity generation across models range from 47%–83% below 2005 in 2030 (68% average) and 66%–87% in 2035 (78% average). Our higher clean electricity deployment and lower emissions under IRA, compared with earlier U.S. modeling, change the baseline for future policymaking and analysis. IRA helps to bring projected U.S. power sector and economy-wide emissions closer to near-term climate targets; however, no models indicate that these targets will be met with IRA alone, which suggests that additional policies, incentives, and private sector actions are needed.

Reducing carbon dioxide (CO2) emissions from power plants can have important \"co-benefits\" for public health by reducing emissions of air pollutants. Here, we examine the costs and health co-benefits, in monetary terms, for a policy that resembles the U.S. Environmental Protection Agency's Clean Power Plan. We then examine the spatial distribution of the co-benefits and costs, and the implications of a range of cost assumptions in the implementation year of 2020. Nationwide, the total health co-benefits were $29 billion 2010 USD (95% CI: $2.3 to $68 billion), and net co-benefits under our central cost case were $12 billion (95% CI: -$15 billion to $51 billion). Net co-benefits for this case in the implementation year were positive in 10 of the 14 regions studied. The results for our central case suggest that all but one region should experience positive net benefits within 5 years after implementation.

The development of climate policy in the United States mirrors international developments, with efforts to initiate a coordinated approach giving way to jurisdictions separately taking actions. The centerpiece of US policy is regulation in the electricity sector that identifies a carbon emissions rate standard (intensity standard) for each state but leaves to states the design of policies, including potentially the use of technology policies, emissions rate averaging, or cap and trade. Differences in policies among states within the same power market could promote predatory behavior resulting in a geographic shift in generation and investment in new resources. This paper examines the coordination problem using a detailed partial equilibrium model of operations and investment. We demonstrate that leading jurisdictions have available a rich set of design options including targetted output based allocation that would impose costs on neighbors and may protect against strategic predation.

Carbon taxes efficiently reduce greenhouse gas emissions, but are criticized as regressive. This paper links dynamic overlapping-generation and micro-simulation models of the United States to estimate the initial incidence of carbon taxes. We find that while carbon taxes are regressive, incidence depends much more on how carbon tax revenue is used. Recycling revenues to cut capital taxes is efficient but exacerbates regressivity. Lump sum rebates are less efficient, but much more progressive, benefitting the three lower income quintiles even when ignoring environmental benefits. A labor tax swap represents an intermediate option, as it is more progressive than a capital tax swap and more efficient than a rebate.

The Affordable Clean Energy (ACE) rule, the US Environmental Protection Agency's (EPA) proposed replacement of the Clean Power Plan (CPP), targets heat rate improvements (HRIs) at individual coal plants in the US. Due to greater plant efficiency, such HRIs could lead to increased generation and emissions, known as an emissions rebound effect. The EPA Regulatory Impact Analysis for the ACE and other analyses to date have not quantified the magnitude and extent of an emissions rebound. We analyze the estimated emissions rebound of carbon dioxide (CO2) and criteria pollutants sulfur dioxide (SO2) and nitrogen oxides (NOX), using results from the EPA's power sector model, under the ACE in 2030 at model coal plants and at the state and national levels compared to both no policy and the CPP. We decompose emissions changes under a central illustrative ACE scenario and find evidence of a state-level rebound effect. Although the ACE reduces the emissions intensity of coal plants, it is expected to increase the number of operating coal plants and amount of coal-fired electricity generation, with 28% of model plants showing higher CO2 emissions in 2030 compared to no policy. As a result, the ACE only modestly reduces national power sector CO2 emissions and increases CO2 emissions by up to 8.7% in 18 states plus the District of Columbia in 2030 compared to no policy. We also find that the ACE increases SO2 and NOX emissions in 19 states and 20 states plus DC, respectively, in 2030 compared to no policy, with implications for air quality and public health. We compare our findings to other model years, additional EPA ACE scenarios, and other modeling results for similar policies, finding similar outcomes. Our results demonstrate the importance of considering the emissions rebound effect and its effect on sub-national emissions outcomes in evaluating the ACE and similar policies targeting HRIs.

In this work, we compare the air quality benefits of a variety of future policy scenarios geared towards controlling EGU (electricity generating units) emissions between the present-day conditions and 2050. While these policies are motivated by reducing CO2 emissions, they also yield significant co-benefits for criteria pollutants, such as ozone and PM2.5. An integrated set of clean energy policies were examined to assess the time-varying costs and benefits of a range of decarbonization strategies, including business as usual and the Affordable Clean Energy plan, with a primary focus on others that look to achieve very low, if not zero, CO2 emissions from the EGU sector by 2050. Benefits assessed include mitigation of greenhouse gas emissions as well as air quality co-benefits. In this introductory work, we describe the potential air quality changes from various clean air policies, to set the stage for upcoming work looking at health and monetized benefits. Emission changes for key pollutants are forecast using the Integrated Planning Model (IPM), which are then transformed into emission inputs for the Community Multiscale Air Quality Model (CMAQ). For all primary scenarios considered that achieve large greenhouse gas decreases, significant reductions in ozone and PM are realized, mainly in the eastern US, and all policies produce air quality benefits.

This paper evaluates the costs to households of a carbon dioxide (CO₂ cap-and-trade program. We find important variation in the distribution of costs of the policy across 11 regions of the country and across income deciles. The introduction of a price on CO₂ emissions is regressive, but this may be outweighed by the distributional effects of CO₂ emissions allowances. We evaluate five alternatives for returning any revenues from auctioning emissions allowances—three are progressive (expansion of the Earned Income Tax Credit and two cap-and-dividend approaches), while the others are either neutral (a reduction in payroll taxes) or amplify regressivity (a reduction in the income tax). Regional differences are most substantial for low-income households.

[This corrects the article DOI: 10.1371/journal.pone.0156308.].