全球智库信息集成服务系统(G2TT): Meeting the US Nationally Determined Contribution and Saving Lives

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Meeting the US Nationally Determined Contribution and Saving Lives 智库博客

时间：2022-01-31 作者： Maya Domeshek;Dallas Burtraw 来源：Resources for the Future (United States)

A new analysis shows that significant and widespread health benefits can be anticipated locally and in the near term if the United States meets its nationally determined contribution.

Many observers view the climate change dilemma as this: the benefits of reducing greenhouse gases vary with geography and accrue largely in the future, whereas the costs of emissions reductions are felt locally and in the present. However, this view of benefits and costs is distorted. Mitigating greenhouse gases yields enormous improvements in air quality that accrue locally and are felt immediately.

In a new study we conducted with Jhih-Shyang Shih and Seth Villanueva of Resources for the Future, along with former Harvard researcher Kathy Fallon Lambert, we look at the national health benefits related to air quality that stem from US actions to meet its nationally determined contribution under the Kyoto Protocol. We use a new method for associating changes in carbon dioxide (CO₂) levels with changes in local air pollutants, estimating the health benefits of a representative policy scenario for reaching the Biden administration’s pledge of a 50–52 percent reduction in net greenhouse gases from economy-wide emissions in the United States by 2030. We find that the health benefits would be widespread and significant—totaling $33 billion per year (in 2010 dollars)—and we can draw additional lessons that have relevance for people and communities across the country.

The policy scenario we analyze involves a combination of cap and trade, sectoral regulation, and innovation policies developed by Environmental Defense Fund. Many of the emissions reductions in the scenario come from non-CO₂ greenhouse gases and from actions outside of the energy sector, but we focus only on the health benefits associated with combustion-related changes in CO₂, analyzed using the National Energy Modeling System model. These reductions account for a 35 percent reduction in CO₂ relative to 2005 levels. The majority of CO₂ reductions come from the electricity sector, but reductions also are evident in the transportation, industry, and residential and commercial buildings sectors.

The analysis downscales combustion-related changes in CO₂ from the regional level based on different types of energy consumption at the state level. Within each state, our analysis associates CO₂ with emissions of sulfur dioxide, nitrogen oxides, and ammonia in each sector and county using the National Emissions Inventory. Finally, we apply a reduced complexity air model (a combination of the Estimating Air pollution Social Impact Using Regression model with the Air Pollution Social Cost Accounting model) to determine what reduced CO₂ emissions would mean for changes in PM2.5 concentrations (pollution from particulate matter that measures less than 2.5 microns in diameter) at the county level across the nation, along with the number of premature deaths avoided.

Alena Mozhjer / Shutterstock

3,800

Nearly 3,800 premature deaths could be avoided annually by the year 2030, and these benefits would accumulate over time.

According to our analysis, nearly 3,800 premature deaths can be avoided annually by the year 2030, and these benefits would accumulate over time. The actual health benefits would be higher, because our estimates look only at the mortality associated with secondary PM2.5 from combustion, rather than primary PM2.5, PM10, nitrogen dioxide, or ozone. Our analysis does not consider mortality changes associated with greenhouse gas reductions that occur outside of the energy sector, greenhouse gas reductions that are unrelated to CO₂ from combustion, the morbidity effects of reduced air pollution, nor other environmental benefits.

In addition, most of the health benefits come from changes in emissions that occur in the electricity sector (sulfur dioxide and nitrogen oxides) and from the transportation sector (mostly nitrogen oxides). This result is unsurprising, given that the electricity and transportation sectors are the sources of the greatest CO₂ reductions. Interestingly, the industrial sector sees some of the biggest health benefits per unit of reduced CO₂. This result in the industrial sector serves as a reminder that simply pursuing the largest CO₂ reductions may not be enough to achieve the biggest health or economic benefits overall—we also need policies that directly target the biggest sources of health-harming pollutants.

These health benefits arise across the United States and are relatively concentrated in population centers. Health benefits per capita, however, are largest in the Midwest (Figure 1), where we expect to see the largest changes in pollution from the electricity sector. These per capita health benefits are broadly consistent with other studies that measure health benefits from emissions reductions in the electricity sector. For example, the Clean Energy Futures study that we participated in last year shows that the largest health benefits from the electricity sector, arising due to climate policy interventions, occur in the Midwest due to reductions in coal-burning power generation.

Figure 1. Monetized Value of Health Benefits from PM2.5 Reductions in 2030 ($ Per Capita)

By distributing the average health benefits in each county to residents of each income level and demographic group within a county, we can estimate the national average of changes in health benefits per group. The national distribution of increased health benefits across income quintiles is relatively even (Figure 2). Distribution across racial and ethnic groups varies across region of residence. For example, Asian and Hispanic populations experience slightly lower health benefits, because their populations are more concentrated in the western United States, where the electricity sector is already cleaner—hence, reductions in pollution will not be as large. All groups realize more than a 15 percent reduction in PM2.5-related mortality. Our analysis cannot speak to the racial and economic disparities in environmental health that often occur at the sub-county level based on household distance from an industrial plant, port, or highway. Our analysis also does not address any racial and economic disparities stemming from differences in the underlying mortality rates and responses to pollution. Nonetheless, an analysis like ours can show broad patterns of changes in pollution and the subsequent effects on people, on average, at the regional and state levels.

Figure 2. Percent Reduction in Premature Deaths

This figure displays the distribution of impacts across households in each group. Boxes describe inter-quartile range around the median. Whiskers describe range to 10th and 90th percentile.

Our new study offers one of the first looks at the health benefits related to air quality from an economy-wide perspective that can be expected if the United States reaches its nationally determined contribution. This investigation provides only a lower bound of the benefits, because we assess the mortality benefits from PM2.5 alone. The study assumes a constant relationship between CO₂ and local air pollutants—an association that might change over time with the growth of carbon capture technology, and a correlation which may be less reliable in the industrial sector. Our analysis also distributes geographic changes in pollution proportionally, based on historical patterns of pollution, which likely will change over time. Nonetheless, in the context of the climate policy dilemma, we demonstrate that significant and widespread health benefits can be anticipated locally and in the near term if the United States manages to meet its nationally determined contribution.