# HEEP Discussion Papers

2020
Metcalf, Gilbert, and James H. Stock. “Measuring the Macroeconomic Impact of Carbon Taxes.” Harvard Environmental Economics Program Discussion Paper Series (2020).Abstract
Economists have long argued that a carbon tax is a cost effective way to reduce greenhouse gas emissions. Increasingly, members of Congress agree. In 2019, seven carbon tax bills were filed in Congress (Kaufman et al., 2019). In addition, the Climate Leadership Council has built bipartisan support for a carbon tax and dividend plan (Baker et al., 2017). In contrast, the Trump Administration is retreating from any climate policy and has taken steps to withdraw from the Paris Accord, citing heavy economic costs to the U.S. economy from meeting the U.S. commitments made during the Obama Administration. In his June 1, 2017 statement on the Accord, for example, the President claimed that the cost to the economy would be “close to \$3 trillion in lost GDP and 6.5 million industrial jobs…” (Trump, 2017). What is the basis for claims about the economic impact of a carbon tax? Economic impacts of a carbon tax typically are estimated using computable general equilibrium (CGE) models (as was done for the report on which Trump based his claims). These models, while helpful, make many simplifying assumptions to remain tractable, including optimization, representative agents, and simplified expectations and dynamics, so at a minimum those estimates would ideally be complemented by empirical evidence on the macroeconomic effects of carbon taxes in practice. With carbon taxes in place in twenty-five countries around the world, including some dating to the early 1990s, empirical analysis of historical experience is now possible. This paper considers carbon taxes in Europe to estimate their impact on GDP and employment. Stock, James H.Climate Change, Climate Policy, and Economic Growth.” Harvard Environmental Economics Program Discussion Paper Series (2020). Sunstein, Cass R.Internalities, Externalities, and Fuel Economy.” Harvard Environmental Economics Program Discussion Paper Series (2020).Abstract It is standard to think that corrective taxes, responding to externalities, are generally or always better than regulatory mandates, but in the face of behavioral market failures, that conclusion might not be right. Fuel economy and energy efficiency mandates are possible examples. Because such mandates might produce billions of dollars in annual consumer savings, they might have very high net benefits, complicating the choice between such mandates and externality-correcting taxes (such as carbon taxes). The net benefits of mandates that simultaneously reduce internalities and externalities might exceed the net benefits of taxes that reduce externalities alone, even if mandates turn out to be a highly inefficient way of reducing externalities. An important qualification is that corrective taxes might be designed to reduce both externalities and internalities, in which case they would almost certainly be preferable to a regulatory mandate. Aldy, Joseph E., Maximillian Auffhammer, Maureen Cropper, Arthur Fraas, and Richard Morgenstern. “Looking Back at Fifty Years of the Clean Air Act.” Harvard Environmental Economics Program Discussion Paper Series, 2020.Abstract Since 1970, transportation, power generation, and manufacturing have dramatically transformed as air pollutant emissions have fallen significantly. To evaluate the causal impacts of the Clean Air Act on these changes, we synthesize and review retrospective analyses of air quality regulations. The geographic heterogeneity in regulatory stringency common to many regulations has important implications for emissions, public health, compliance costs, and employment. Cap-and-trade programs have delivered greater emission reductions at lower cost than conventional regulatory mandates, but policy practice has fallen short of the cost-effective ideal. Implementing regulations in imperfectly competitive markets have also influenced the Clean Air Act’s benefits and costs. Stock, James H.Data Gaps and the Policy Response to the Novel Coronavirus.” Harvard Environmental Economics Program Discussion Paper Series (2020).Abstract This note lays out the basic Susceptible-Infected-Recovered (SIR) epidemiological model of contagion, with a target audience of economists who want a framework for understanding the effects of social distancing and containment policies on the evolution of contagion and interactions with the economy. A key parameter, the asymptomatic rate (the fraction of the infected that are not tested under current guidelines), is not well estimated in the literature because tests for the coronavirus have been targeted at the sick and vulnerable, however it could be estimated by random sampling of the population. In this simple model, different policies that yield the same transmission rate β have the same health outcomes but can have very different economic costs. Thus, one way to frame the economics of shutdown policy is as finding the most efficient policies to achieve a given β, then determining the path of β that trades off the economic cost against the cost of excess lives lost by overwhelming the health care system. 2019 Stavins, Robert. “The Future of U.S. Carbon-Pricing Policy.” Harvard Environmental Economics Program Discussion Paper (2019).Abstract There is widespread agreement among economists – and a diverse set of other policy analysts – that at least in the long run, an economy-wide carbon pricing system will be an essential element of any national policy that can achieve meaningful reductions of CO2 emissions cost-effectively in the United States. There is less agreement, however, among economists and others in the policy community regarding the choice of specific carbon-pricing policy instrument, with some supporting carbon taxes and others favoring cap-and-trade mechanisms. This prompts two important questions. Which – if either – of the two major approaches to carbon pricing is superior in terms of relevant criteria, including but not limited to efficiency, cost-effectiveness, and distributional equity? And which of the two approaches is more likely to be adopted in the future in the United States? This paper addresses these questions by drawing on both normative and positive theories of policy instrument choice as they apply to U.S. climate change policy, and draws extensively on relevant empirical evidence. The paper concludes with a look at the path ahead, including an assessment of how the two carbon-pricing instruments can be made more politically acceptable. Stavins, Robert, Todd Schatzki, and Rebecca Scott. “Transitioning To Long-Run Effective and Efficient Climate Policies.” Harvard Environmental Economics Program, 2019. 2018 Richard, Schmalensee, and Robert Stavins. “Policy Evolution Under the Clean Air Act.” Harvard Environmental Economics Program, 2018.Abstract The U.S. Clean Air Act, passed in 1970 with strong bipartisan support, was the first environmental law to give the Federal government a serious regulatory role, established the architecture of the U.S. air pollution control system, and became a model for subsequent environmental laws in the United States and globally. We outline the Act’s key provisions, as well as the main changes Congress has made to it over time. We assess the evolution of air pollution control policy under the Clean Air Act, with particular attention to the types of policy instruments used. We provide a generic assessment of the major types of policy instruments, and we trace and assess the historical evolution of EPA’s policy instrument use, with particular focus on the increased use of market-based policy instruments, beginning in the 1970s and culminating in the 1990s. Over the past fifty years, air pollution regulation has gradually become much more complex, and over the past twenty years, policy debates have become increasingly partisan and polarized, to the point that it has become impossible to amend the Act or pass other legislation to address the new threat of climate change. Schatzki, Todd, and R. N. Stavins. “Key Issues Facing California's GHG Cap-and-Trade System for 2021-2030.” Cambridge, MA: Harvard Environmental Economics Program, 2018.Abstract California’s Greenhouse Gas (GHG) cap-and-trade program is a key element of the suite of policies the State has adopted to achieve its climate policy goals. The passage of AB 398 (California Global Warming Solutions Act of 2006: market-based compliance mechanisms) extended the use of the cap-and-trade program for the 2021-2030 period, while also specifying modifications of the program’s “cost containment” structure and directing CARB to “[e]valuate and address concerns related to overallocation in [ARB’s] determination of the allowances available for years 2021 to 2030.” The changes being considered by CARB will not only affect the program’s stringency, but also its performance by affecting the ability of the “cost containment” structure to mitigate allowance price volatility and the risk of suddenly escalating allowance prices. Gerarden, Todd D.Demanding Innovation: The Impact of Consumer Subsidies on Solar Panel Production Costs.” Cambridge, MA: Harvard Environmental Economics Program, 2018.Abstract This paper analyzes the impacts of consumer subsidies in the global market for solar panels. Consumer subsidies can have at least two effects. First, subsidies shift out demand and increase equilibrium quantities, holding production costs fixed. Second, subsidies may encourage firms to innovate to reduce their costs over time. I quantify these impacts by estimating a dynamic structural model of competition among solar panel manufacturers. The model produces two key insights. First, ignoring long-run supply responses can generate biased estimates of the effects of government policy. Without accounting for induced innovation, subsidies increased global solar adoption 49 percent over the period 2010-2015, leading to over \$15 billion in external social benefits. Accounting for induced innovation increases the external benefits by at least 22 percent. Second, decentralized government intervention in a global market is inefficient. A subsidy in one country increases long-run solar adoption elsewhere because it increases investment in innovation by international firms. This spillover underscores the need for international coordination to address climate change.
Chen, Cuicui. “Slow Focus: Belief Evolution in the U.S. Acid Rain Program.” Cambridge, MA: Harvard Environmental Economics Program, 2018.Abstract
I study ﬁrm behavior in new markets by examining coal-dependent private electric utili-ties’ beliefs about the sulfur dioxide allowance price following the implementation of the U.S. Acid Rain Program. The program is the ﬁrst large-scale cap-and-trade program, exposing the electric utility industry to a wholly novel market for pollution allowances. I estimate ﬁrms’ beliefs about the allowance price from 1995 to 2003 using a ﬁrm-level dynamic model of allowance trades, coal quality, and emission reduction investment. I ﬁnd that ﬁrms ini-tially underestimate the role of market fundamentals as a driver of allowance prices, but over time their beliefs appear to converge toward the stochastic process of allowance prices. Such beliefs in the ﬁrst ﬁve years of the program cost ﬁrms around 10% of their proﬁts. Beliefs also change the relative eﬃciency of cap-and-trade programs and emission taxes.
2017
Schmalensee, Richard, and Robert N. Stavins. “The Design of Environmental Markets: What Have We Learned From Experience With Cap and Trade?Oxford Review of Economic Policy 33, no. 4 (2017): 572–588.Abstract
Abstract: This article reviews the design of environmental markets for pollution control over the past 30 years, and identifies key market-design lessons for future applications. The focus is on a subset of the cap-and-trade systems that have been implemented, planned, or proposed around the world. Three criteria led us to the selection of systems for review. First, among the broader class of tradable permit systems, our focus is exclusively on cap-and-trade mechanisms, thereby excluding emission-reductioncredit or offset programmes. Second, among cap-and-trade mechanisms, we examine only those that target pollution abatement, and so we do not include applications to natural resource management, such as individual transferable quota systems used to regulate fisheries. Third, we focus on the most prominent applications—those that are particularly important environmentally, economically, or both. Keywords: environmental markets, cap-and-trade system, air pollution, global climate change JEL classification: Q58, Q28, Q53, Q54
Coglianese, John, Todd D. Gerarden, and James Stock. “The Effects of Fuel Prices, Regulations, and Other Factors on U.S. Coal Production, 2008-2016.” Cambridge, Massachusetts, USA: Harvard Project on Climate Agreements, 2017.
Greenstone, Michael, Cass R. Sunstein, and Sam Ori. “The Next Generation of Transportation Policy.” Cambridge, Massachusetts, USA: Harvard Project on Climate Agreements, 2017.Abstract
Motor vehicle fuel-economy standards have long been a cornerstone of U.S. policy to reduce fuel consumption in the light-duty vehicle fleet. In 2011 and 2012 these standards were significantly expanded in an effort to achieve steep reductions in oil demand and greenhouse gas emissions through 2025, consistent with long-term U.S. policy goals. As a policy approach, however, standards that focus on efficiency alone, as opposed to lifetime consumption, impose unnecessarily high costs and do not deliver guaranteed petroleum savings. On the basis of a commitment to cost-benefit analysis, defining U.S. regulatory policy for more than 30 years, we propose a novel policy solution that would implement a cap-and-trade system in transportation. Acknowledging that the very idea of cap and trade has become controversial, we show that this approach would increase the certainty of reductions in fuel consumption in transportation and do so at a far lower cost per gallon avoided. Such an approach is consistent with the regulatory authority existing at key federal agencies.
Baker, Jonathan. “Subsidies for Succulents: Evaluating the Las Vegas Cash-for-Grass Rebate Program.” Cambridge, Massachusetts, USA: Harvard Environmental Economics Program, 2017.Abstract
I estimate the water savings and property value effects of a Las Vegas area water conservation program that subsidizes conversions of lawn to desert landscape. Using event studies and panel fixed-effects models, I find that the average conversion reduces baseline water consumption by 21 percent and increases property values by about 1 percent. In addition, my results show that water savings remain relatively stable over time; that water savings are inversely proportional to annual program take-up; that participants with high pre-conversion water demand save more water than participants with lower pre-conversion water demand; and that a 6 percent price increase would have achieved equivalent savings. I find little evidence of property value spillovers to neighboring properties. The program saves water at an annual rate of \$4.84/kgal and if I include an estimate of the scarcity value of water, generates net benefits of \$2.00 per square foot of desert landscape converted.
Park, Jisung. “Will We Adapt? Labor Productivity and Adaptation to Climate Change.” Cambridge, Massachusetts, USA: Harvard Environmental Economics Program, 2017.Abstract

This study explores the for labor-related production impacts of temperature stress both for its own interest and to understand the scope for adaptation to climate change. Focusing on non-agricultural output, I find that hot temperature exerts a significant causal impact on local labor product, with substantially larger effects in highly ex-posed industries such as construction, manufacturing, and transportation. Places that experience more extreme heat exposure in expectation (e.g. Houston, Orlando) exhibit lower impacts per hot day than cooler regions (e.g. Boston, San Francisco). A year with 10 additional 90°F days would reduce output per capita in highly exposed sectors by -3.5% in counties in the coldest quintile and -1.3%, roughly a third, in the warmest quintile. County-level air-conditioning penetration explains a large proportion of these differences. While these estimates suggest adaptation to heat stress in the long-run, they also imply realistic limits, at least given current technologies.

2016
Weitzman, Martin L.On a World Climate Assembly and the Social Cost of Carbon.” Cambridge, Massachusetts, USA: Harvard Environmental Economics Program, 2016.Abstract

This paper postulates the conceptually useful allegory of a futuristic "World Climate Assembly" (WCA) that votes for a single worldwide price on carbon emissions via the basic democratic principle of one-person one-vote majority rule. If this WCA framework can be accepted in the first place, then voting on a single internationally-binding minimum carbon price (the proceeds from which are domestically retained) tends to counter self-interest by incentivizing countries or agents to internalize the externality. I attempt to sketch out the sense in which each WCA-agent's extra cost from a higher emissions price is counter-balanced by that agent's extra benefit from inducing all other WCA-agents to simultaneously lower their emissions in response to the higher price. The first proposition of this paper derives a relatively simple formula relating each emitter's single-peaked most-preferred world price of carbon emissions to the world "Social Cost of Carbon" (SCC). The second and third propositions relate the WCA-voted world price of carbon to the world SCC. I argue that the WCA-voted price and the SCC are unlikely to differ sharply. Some implications are discussed. The overall methodology of the paper is a mixture of mostly classical with some behavioral economics.

Haefele, Michelle, John Loomis, and Linda J. Bilmes. “Total Economic Valuation of the National Park Service Lands and Programs: Results of a Survey of the American Public.” Cambridge, Massachusetts, USA: Harvard Environmental Economics Program, 2016.
Sullivan, Daniel M.The True Cost of Air Pollution: Evidence from House Prices and Migration.” Cambridge, Massachusetts, USA: Harvard Environmental Economics Program, 2016.Abstract

In this paper, I present evidence that current economics research significantly underestimates the effects of air pollution, regardless of the outcome of interest. This bias exists even in quasi-experimental estimates and arises from the way researchers define individual-level pollution exposure. A polluter’s effect on nearby residents changes dramatically with the direction of the wind, and most popular methods, including geographic diff-in-diffs and monitor-based interpolations, are unable to account for such sharp changes in exposure over short distances. To solve this problem, I use an atmospheric dispersion model, which explicitly accounts for meteorological conditions, to determine the effect of every polluting firm on every house in greater Los Angeles. I then estimate the effect of NOx emissions on house prices and neighborhood composition using the exogenous variation in emissions caused by the California Electricity Crisis of 2000 and a cap-and-trade program in greater Los Angeles. The estimated price response is much larger than past estimates and implies that the social value of the cap-and-trade program is roughly \\$502 million per year, 15 times larger than the associated abatement costs. However, when based on conventional measures of pollution exposure, this estimated valuation is small and statistically indistinguishable from zero. The estimated neighborhood sorting response suggests that, despite the high aggregate value, low-income households may not have benefited much from the improvement in air quality.

Stolper, Samuel. “Who Bears the Burden of Energy Taxes? The Critical Role of Pass-Through.” Cambridge, Massachusetts, USA: Harvard Environmental Economics Program, 2016.Abstract

Existing estimates of energy tax incidence assume that the pass-through of taxes to final consumer prices is uniform across the affected population. I show that, in fact, variation in local market conditions drives significant heterogeneity in pass-through, and ignoring this can lead to mistaken conclusions about the distributional impacts of energy taxes. I use data from the Spanish retail automotive fuel market to estimate station-specific pass-through, focusing on the effects of competition and wealth. A novel informational mandate provides access to a national, station-daily panel of retail diesel prices and characteristics and allows me to investigate market composition at a fine level. Event study and difference-in-differences regression reveal that, while retail prices rise nearly one-for-one (100%) with taxes on average, station-specific pass-through rates range from at least 70% to 115%. Greater market power – measured by brand concentration and spatial isolation – is strongly associated with higher pass-through, even after conditioning on detailed demand-side characteristics. Furthermore, pass-through rises monotonically in area-average house prices. While a conventional estimate of the Spanish diesel tax burden suggests roughly equivalent incidence across the wealth distribution, overlaying the effect of heterogeneous pass-through reveals the tax to be unambiguously progressive.