Metrics matter, a Formal comment on Ward et al Plos-One 2016 paper : Is decoupling GDP growth from environmental impact possible?

TL;DR

This paper critically re-evaluates Ward et al. (2016), correcting data errors and finding that the original claim of relative decoupling between economic growth and environmental impact is less supported, reinforcing the unlikelihood of absolute decoupling.

Contribution

It identifies and corrects key data errors in Ward et al. (2016), providing revised analysis that challenges their conclusions on decoupling.

Findings

Lower levels of energy-GDP decoupling after correction

No evidence of materials-GDP decoupling at global level

Reinforces the implausibility of future absolute decoupling

Abstract

The Ward et al. (2016) Plos-One paper is an important, heavily-cited paper in the decoupling literature. The authors present evidence of 1990-2015 growth in material and energy consumption and GDP at a world level, and for selected countries. They find only relative decoupling has occurred, leading to their central claim that future absolute decoupling is implausible. However, the authors have made two key errors in their collected data: GDP data is in current prices which includes inflation, and their global material use data is the total mass of fossil energy materials. Strictly, GDP data should be in constant prices to allow for its comparison over time, and material inputs to an economy should be the sum of mineral raw materials. Amending for these errors, we find much smaller levels of energy-GDP relative decoupling, and no materials-GDP decoupling at all at a global level. We check these new results by adding data for 1900-1990 to provide a longer time series, and find consistently low (and even no) levels of global relative decoupling of material use. The central claim for materials over the implausibility of future absolute decoupling therefore not only remains valid but is reinforced by the corrected datasets.