天然气价格下跌对美国制造业就业的影响The Impacts of Lower Natural Gas Prices on Jobs in the US Manufacturing Sector i

尽管就业和产出的相对比重长期下降，但美国制造业已从2008-9年的衰退中大幅反弹。事实上，这是自20世纪80年代初以来该行业首次完全恢复其产出份额的衰退（Celasun等人。2014年）。在国际上，美国约占全球制造业的20%，与中国大致相同。尽管国内制造业的就业还没有完全恢复到衰退前的水平，但该行业仍然占到该国高工资蓝领工作岗位的一半以上（麦肯锡全球研究所，2012年）。制造业复苏的同时，天然气价格也大幅下跌（EIA2013A）。不断下降的生产成本，特别是来自页岩地层的生产成本，极大地增加了产量和估计储量，降低了消费者的天然气价格。2007年至2012年间，实际天然气价格下降了约50%。2005年以来，国内天然气产量增长50%，2016年达到2.8万亿立方英尺（tcf）。仅在2011年的一年时间里，美国能源信息署（EIA）就将其技术上可开采页岩气的估计值翻了一番多，达到827tcf。随后，对估算值进行了多次上调，最近的估算表明，美国可能拥有超过1100 tcf的技术可采页岩气资源（EIA 2013b）。结合其对非页岩气资源的估计，EIA预计美国的技术可采天然气储量总体超过100年（EIA 2017）。很少有专家质疑美国经济正从天然气产量增加和价格下降中受益。国内生产总值增长、天然气生产部门扩大就业、降低电力和天然气价格、改善贸易平衡以及增加税收，这些都是共同体现的收益。制造业直接将天然气作为燃料，并通过发电间接消耗天然气。电力和制造业都大幅增加了天然气消费，住宅和商业部门几乎没有增长。根据标准的微观经济学理论，天然气等投入品价格的下降会降低边际生产成本，增加产出，降低产出价格。产量的增加增加了就业，而天然气价格相对于工资的下降可以增加或减少就业，这取决于天然气和就业在生产中是互补的还是替代的。就业增长的规模、地点和时机尚不清楚，是政策界争论不休的话题。这一点尤其适用于对个别行业或国家特定地区的微观考察。天然气价格走低也引发了有关未来天然气出口的政策辩论。与其他国家相比，美国的低价格增加了天然气出口的盈利能力，无论是通过管道还是通过液化形式的船舶。与此同时，天然气出口增加将提振美国价格，有利于天然气生产商，但损害消费者，特别是天然气密集型行业。这些相反的影响是就应允许出口快速增长还是应限制增长展开激烈政策辩论的基础。最近的几项研究试图估计最近天然气价格下跌对制造业就业的影响。这些估计表明，天然气价格下跌带来的制造业就业增长可能相当大，如www.rff.org | 1 Resources for the Future | Gray，Linn，在能源密集度最高的十分之一的行业中，摩根斯坦恩高达9.1%，在能源密集度最高的行业（化肥制造业）中，摩根斯坦恩高达30%。1，然而，这些论文依赖于聚集的数据，并几乎没有注意到其他因素可能与天然气价格，也影响就业，如熟练的劳动力可用性，接近中间输入，或其他位置特定的变量。为了评估天然气价格对制造业复苏的影响，并描述扩大天然气出口的潜在影响，我们试图在本文的最新文献基础上取得一些进展。首先，我们分析了天然气价格对地方（县级）就业的影响，定义在高度细分的工业层面。这一细节有助于分析天然气价格下跌的总体和地理影响，而其他研究则依赖于国家一级的数据。县级数据的使用允许我们进行第二个前进，即考虑其他位置特定的因素，例如接近关键输入。这种方法建立在集聚和产业动态的文献基础上（例如，Ellison和Glaeser 1997）。使用汇总数据无法解释这些因素，这些因素最终与天然气价格相关。因此，对特定地点因素的控制大大减少了观察到的天然气价格下降对就业的估计影响。我们使用机密的工厂级普查信息来开发一个简化的面板数据模型，将制造业就业与天然气和电价联系起来，控制1这些计算不包括与提供直接用于石油和天然气生产的材料的行业相关的间接影响，比如增加了钢厂的产量，以生产钻机上使用的套管。对于其他可能影响增长的因素，并估计长期（五年）影响。我们发现，天然气价格对县级就业的影响在统计学上是显著的，其影响通常随着天然气强度的增加而增加。与卡恩和曼苏尔（2013）等先前研究的结果一致，电价也影响就业，这表明天然气价格直接和间接影响制造业就业。与其他研究类似，我们的估计包括天然气价格变化引起的天然气和劳动力之间的生产扩张和替代的影响。相应地，所得到的模型估计值被用来模拟2007年至2012年间50%的天然气价格下降所带来的就业增长。我们发现，天然气价格的下跌使制造业的整体就业率上升了0.6%。这些对天然气价格引起的收益的估计比最近其他研究报告的要小，这至少部分是由我们对聚集因素的控制所解释的。相对于观察到的制造业就业总量的波动，我们估计的就业影响也很小：2007年至2012年间，制造业就业总量下降了17.8%，2010年至2012年后衰退期间，制造业就业总量增长了6.1%。尽管天然气价格对制造业就业总量的影响不大，但对天然气密集型行业的就业确实产生了实质性影响。2007年至2012年期间，天然气价格的下降使相对天然气密集型行业（即，位于www.rff.org | 2未来资源| Gray、Linn和Morgenstern天然气密度分布前四分之一的行业）的就业率增加了1.8%，这比整个行业的估计值高出三倍制造业，反映了天然气作为天然气密集型产业投入的重要性。与总体估计一样，这一估计值小于其他近期研究报告中的估计值。2在2007-12年和2010-12年期间，天然气密集型行业的就业增长率始终高于制造业平均水平。总的来说，天然气价格的下降解释了天然气密集型行业就业增长速度加快一半以上的原因。因此，天然气价格只解释了这一时期就业总量变化的一小部分，但在就业增长中跨行业变化的很大一部分。预计天然气出口的增长对天然气价格的影响相对较小，将在3%至9%之间提高（EIA 2014）。因此，对我们模型的模拟表明，出口增加对整个制造业就业的影响相对较小，所有行业的就业减少0.1%至0.3%，这取决于出口引起的价格变化的幅度。对于天然气密集型行业，就业率将下降0.2%至0.5%。本文第2节回顾了国内天然气价格与制造业就业之间联系的最新文献。第3节和第4节描述了建模设置和工厂级数据。模型估计和仿真结果见第5节和

Despite long-term declines in its relative share of employment and output, US manufacturing has rebounded sharply from the 2008–9 recession. In fact, this is the first recession where the sector has fully recovered its share of output since the early 1980s (Celasun et al. 2014). Internationally, the United States represents about 20 percent of global manufacturing—roughly the same share as China. Even though employment in domestic manufacturing has not fully returned to prerecession levels, the sector still accounts for more than half of the high-wage blue-collar jobs in the country (McKinsey Global Institute 2012).  The recovery of the manufacturing sector has coincided with a sharp drop in natural gas prices (EIA 2013a). Declining production costs, particularly from shale formations, have dramatically increased output and estimated reserves and reduced gas prices for consumers. Between 2007 and 2012, real natural gas prices declined by about 50 percent. Since 2005, domestic natural gas production has increased by 50 percent, reaching 2.8 trillion cubic feet (tcf) in 2016. In one year alone, 2011, the US Energy Information Administration (EIA) more than doubled its estimates of technically recoverable shale gas to 827 tcf. Subsequently, estimates have been revised upward several times, with recent estimates suggesting the United States may have more than 1,100 tcf of technically recoverable shale gas resources (EIA 2013b). Combined with its estimates of non–shale gas resources, EIA projects that the United States has more than 100 years of technically recoverable natural gas reserves overall (EIA 2017).  Few experts dispute that the US economy is benefiting from higher natural gas production and lower prices. GDP growth, employment expansion in the natural gas production sector, lower electricity and natural    gas prices, improvements in trade balance, and increases in tax revenues are all among the commonly articulated gains. The manufacturing sector consumes natural gas directly as a fuel and indirectly through its use in electricity generation. Both the electricity and manufacturing sectors have increased their gas consumption substantively, with few gains in the residential and commercial sectors.  Based on standard microeconomic theory, a decline in the price of an input, such as natural gas, reduces marginal production costs, increases output, and reduces output prices. The output increase raises employment, and the decrease in natural gas price relative to wages can increase or decrease employment depending on whether natural gas and employment are complements or substitutes in production. The size, location, and timing of the job gains are unclear and are the subject of considerable debate in policy circles. This is particularly true when looking granularly at individual industries or at particular regions of the country.  Lower natural gas prices have also generated a policy debate about future natural gas exports. Low prices in the United States relative to other countries have increased the profitability of exporting natural gas, either by pipeline or by ship in liquefied form. At the same time, an increase in gas exports would boost US prices, benefiting natural gas producers but harming consumers, particularly gas-intensive industries. These opposing effects are the basis for a vigorous policy debate over whether exports should be allowed to grow rapidly or growth should be restrained.  Several recent studies have attempted to estimate the effects of the recent decline in natural gas prices on manufacturing employment. These estimates suggest that the manufacturing employment gains from the gas price declines are potentially quite large—as     www.rff.org  |  1  Resources for the Future  |  Gray, Linn, and Morgenstern    much as 9.1 percent for industries in the top decile of energy intensity and up to 30 percent for the most energy-intensive industry (fertilizer manufacturing). 1 However, these papers rely on aggregated data and pay virtually no attention to other factors that may be correlated with natural gas prices and also affect employment, such as skilled labor availability, proximity to intermediate inputs, or other location-specific variables.  To assess the effects of natural gas prices on the recovery of the manufacturing sector and to characterize the potential effects of expanding natural gas exports, we attempt to make several advances over the recent literature in this paper. First, we analyze the effects of natural gas prices on local (county-level) employment, defined at a highly disaggregated industrial level. This detail enables an analysis of the aggregate and geographic effects of natural gas price declines, in contrast to the other studies, which have relied on national-level data. The use of county-level data allows us to make a second advance—namely, the consideration of other location-specific factors, such as proximity to key inputs. This approach builds on the literature on agglomeration and industry dynamics (e.g., Ellison and Glaeser 1997). Accounting for these factors is not possible using aggregated data, and these factors turn out to be correlated with natural gas prices. Consequently, controlling for the location-specific factors substantially reduces the estimated effects of the observed natural gas price declines on employment.  We use confidential plant-level Census information to develop a reduced -form panel data model linking manufacturing employment to natural gas and electricity prices, controlling    1These calculations exclude indirect effects associated with industries providing materials directly used in oil and gas production, such as the increased output of steel mills to produce the casing used on drilling rigs.    for other factors that may affect growth, and estimate long-term (five-year) effects. We find that natural gas prices have a statistically significant effect on county-level employment, with effects typically increasing with natural gas intensity. Consistent with the findings of previous studies such as Kahn and Mansur (2013), electricity prices also affect employment, which suggests that natural gas prices affect manufacturing employment both directly and indirectly. Similarly to other studies, our estimates include the effects of both expanding production and substitution between natural gas and labor induced by changes in natural gas prices.  The resulting model estimates, in turn, are used to simulate the employment gains arising from the 50 percent natural gas price decline that occurred between 2007 and 2012. We find that the drop in natural gas prices raised overall manufacturing employment by 0.6 percent. These estimates of the gas price–induced gains are smaller than those reported in other recent studies, which is at least partly explained by our controlling for the agglomeration factors. Our estimated employment impacts are also small relative to the observed swings in aggregate manufacturing employment over the period: either the aggregate decline of 17.8 percent between 2007 and 2012 or the aggregate increase of 6.1 percent in the post-recession period between 2010 and 2012.  Although natural gas prices had modest effects on aggregate manufacturing employment, they did have substantial effects on employment in gas -intensive industries. The decline in natural gas prices between 2007 and 2012 increased employment by 1.8 percent in the relatively gas -intensive industries (i.e., those in the top quartile of the     www.rff.org  |  2  Resources for the Future  |  Gray, Linn, and Morgenstern    gas intensity distribution), which is three times greater than the estimate for the entire manufacturing sector, reflecting the importance of natural gas as an input for the gas-intensive industries. Like the aggregate estimate, this estimate is smaller than that reported in other recent studies.2 In both the 2007–12 and 2010–12 periods, the gas-intensive industries experienced consistently higher employment growth than the manufacturing average. Overall, the decline in natural gas prices explains more than half the faster employment growth rates observed in the gas-intensive industries. Thus natural gas prices explain only a small portion of the aggregate employment changes but large shares of cross-industry variation in employment growth during these time periods.  Increases in natural gas exports are expected to have relatively small impacts on natural gas prices, raising them somewhere between 3 and 9 percent (EIA 2014). Consequently, simulations of our model suggest that higher exports would have relatively small impacts on overall manufacturing employment, reducing employment by 0.1 to 0.3 percent across all industries, depending on the magnitude of the export-induced price change. For the gas-intensive industries, the employment reductions would be 0.2 to 0.5 percent.  Section 2 of the paper reviews the recent literature on the link between domestic natural gas prices and manufacturing employment. Sections 3 and 4 describe the modeling setup and plant-level data. The model estimates and simulation results are presented in sections 5 and