La curva de Kuznets ambiental, en acción

En los últimos días se ha hablado en EEUU (en medios generalistas como Vox) de cómo la industria de allá está siendo capaz de reducir sus emisiones sin que esto suponga siempre una deslocalización. El paper de Levinson, utilizando una metodología de números índices, separa el efecto estructural del efecto "eficiencia", y concluye que la emisiones han bajado mucho por el segundo efecto, pero sin determinar las causas.

From 1990 to 2008, the real value of US manufacturing output grew by one-third while the pollution emitted from US factories fell by two-thirds. What accounts for this cleanup? Prior studies have documented that a relatively small share can be explained by changes in the composition of US manufacturing - a shift towards producing relatively more goods whose production processes involve less pollution. Those studies attribute the unexplained majority to "technique", a mix of input substitution, process changes, and end-of-pipe controls. But because that technique effect is a residual left over after other explanations, any errors or interactions in the original calculation could inflate the estimated technique. In this paper I provide the first direct estimate of the technique effect. I combine the National Emissions Inventories with the NBER-CES Manufacturing Industry Database for each of over 400 manufacturing industries. I aggregate across industries using analogs to the Laspeyres and Paasche price indexes for each of six major air pollutants. The calculations using this direct estimation of the technique effect support the research findings using indirect measures. From 1990 to 2008, production technique changes account for more than 90 percent of the overall cleanup of US manufacturing.

Bueno, pues ese hueco lo tratan de llenar Shapiro y Walker, que en su paper dicen que la causa fundamental es la regulación.

Between 1990 and 2008, emissions of the most common air pollutants from U.S. manufacturing fell by 60 percent, even as real U.S. manufacturing output grew substantially. This paper develops a quantitative model to explain how changes in trade, environmental regulation, productivity, and consumer preferences have contributed to these reductions in pollution emissions. We estimate the model's key parameters using administrative data on plant-level production and pollution decisions. We then combine these estimates with detailed historical data to provide a model-driven decomposition of the causes of the observed pollution changes. Finally, we compare the model-driven decomposition to a statistical decomposition. The model and data suggest three findings. First, the fall in pollution emissions is due to decreasing pollution per unit output within narrowly defined products, rather than to changes in the types of products produced or changes to the total quantity of manufacturing output. Second, the implicit pollution tax that rationalizes firm production and abatement behavior more than doubled between 1990 and 2008. Third, environmental regulation explains 75 percent or more of the observed reduction in pollution emissions from manufacturing.

En el fondo, una señal optimista de que es posible reducir la contaminación ambiental sin reducir el consumo. Imaginad si además redujéramos el consumo...

Eso sí, cuidado, porque en ningún caso hablan de CO2, sino de contaminantes "convencionales": SO2, partículas, NOx, etc. Y, como era de esperar, los NOx han sido los que menos han bajado.