Thread by @wang_seaver

This study is generating buzz + looked fascinating, so I read the press release, media briefing + full report yesterday.

Key findings are probably approximately correct, but these results were guaranteed given the methodology used. (THREAD)

https://twitter.com/guardian/status/1307830423347752962

The authors use a top-down approach to assign a country’s total emissions (private + govt) to each household based on a monotonic relationship proportional to household income, using the national income distribution and Global Carbon Proj carbon emissions data for each year. (1)

In other words, the study is virtually hard-coded to allocate more emissions to households with higher incomes, irregardless of actual consumption patterns. To be fair, relationship btwn income + emissions is generally borne out by consumer habit surveys, but… (2)

...it’s important to note that this study uses an explicit assumption that emissions are directly proportional to income to find that the global wealthy emit more - which is a guaranteed outcome on any country/planet with high income inequality. (3)

Again, the emissions vs income assumption is probably roughly correct, although there will be differences by country on the elasticity of emissions with increasing income that the Oxfam study largely declined to consider. (4)

(Figure from Appendix A of the report)

But there is a difference between this top-down approach with a guaranteed result and a bottom-up study that directly evaluates the emissions associated with consumption habits of households with different incomes. The latter is of course much, much harder to conduct. (5)

My point is that this study doesn’t tell us anything we didn’t already know, and doesn’t actually provide any additional proof, since the methodology basically assumes the answer to the research question. (6)

Since the per-capita emissions figures are directly tied to income, this study is really in essence a commentary on extreme wealth and income inequality.

Which is an injustice that we absolutely need to solve, for the record. (7)

This study would have been more valuable had it considered varying elasticity of emissions with income by country, and also considered emissions contributions based on real income thresholds rather than percentiles. (8)

As it is, the report has to grapple awkwardly with the fact that the richest 10% and middle 40% globally grow from 533 to 738 million and 2.13 to 2.95 billion respectively over the period from 1990 - 2015. (9)

Similarly from their data spreadsheet, the minimum threshold for entering the middle 40% (50-90th percentile of global annual income) grew from $2097 to $5566 (in 2011 dollars) from 1990 to 2015 if I’m interpreting correctly. (10)

Also worth noting this study considers fossil fuel consumption emissions only. Entirely fair given data limitations, but the 24.5% of global emissions from agriculture, land use, waste, and cement are probably more equitably distributed. (11)

To conclude, is it correct that the world’s richest (keeping in mind that you only need an income of $38000 USD per year to make the top 10%) are the most responsible for emissions? Absolutely. We knew that. (12)

But this report doesn’t really provide new proof of that so much as it conducts a thought experiment based on a hard relationship between income and emissions.

Press release and links to PDF report can be found here:

oxfam.org/en/press-relea…

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