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It’s the Denominator, Stupid

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Today’s piece Empire of Carbon by Paul Krugman of the NY Times deals with China, greenhouse gas (GHG) emissions, carbon, etc.

According to the article, China is the largest carbon dioxide emitter on the planet. But fair is fair: they got a lot more bodies over there producing all that gas. On a per-capita basis that attempts to measure emission per-person, China’s level is far below that of the US, according to the atrticle.

But then Krugman goes on to mention something that has long been a point of my own. It’s not just the number of people that matters; it’s the amount of economic activity that matters. After all, commercial and industrial profit-making activities also consume and emit. And since the US does much more of that on a per-capita basis, that is, it has higher per-capita GDP, it turns out that the US-level of emissions, on a per-GDP basis, is actually half of China’s.

It’s the denominator, stupid.

Now we can argue about which one is the fair measure of who is a “worse” emitter. [ Personally, I think total emissions per GDP is the right measure as it reflects not the just the numbers of people, but what the people are producing. ]

In fact, we should be arguing about it. People that are interested in gaming the system for their own interests - economic, nationalistic, etc - will invariably cite the measure that supports their interest. Unfortunately, most people are not sufficiently numerate to question whether the measure selected is the metric that matters, so too often it goes unchallenged.

Which metric matters? That’s gotta be part of the discussion.