This is excellent news:

Seattle is one of the first major U.S. cities to claim it has cut greenhouse-gas emissions enough to meet the targets of the international Kyoto treaty aimed at combating global warming.

The achievement, at a time when the city has enjoyed a boom in population and jobs, sets Seattle apart both from the nation as a whole and other cities that have seen greenhouse gases soar in recent years.

Well, good on Seattle. But at risk of sounding like a stick in the mud, there’s still a question mark in my mind about how much progress the city’s really made.

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  • The big problem is that this kind of greenhouse accounting isn’t just tough, it’s mind-bogglingly tough. (And in the spirit of full disclosure, our own Eric de Place is married to one of the authors of Seattle’s GHG inventory.)

    The difficulties are myriad. First off, there are no consistent accounting standards for how a city should run a greenhouse inventory—which means that the exercise requires dozens or even hundreds of judgment calls. How does Seattle account for flights taken by city residents to and from SeaTac (which, after all, is outside of Seattle city limits)? How does a city track electricity generated in some other part of the state, or even in another state altogether? What about gasoline that’s purchased outside the city, but used in city limits (or vice versa). Should the city count heating emissions related to a particularly cold or warm winter as evidence of lasting changes? The decisions are virtually endless. And while I have no reason to doubt that the Seattle inventory’s choices were made in good faith, there’s no question that an equally defensible set of accounting choices might have yielded different results.

    One of the biggest challenges in a city inventory is accounting for materials flows—especially, the things Seattle residents buy that were manufactured or grown elsewhere.

    Take food; a fair chunk of Seattle’s emissions, broadly defined, come from the food we eat. Yet trends in agricultural inputs, and long-distance food transport, simply aren’t reflected in a GHG inventory that focuses on the city itself. We could be eating higher up on the food chain, and our food could be traveling farther and farther farm fields to our plates; but a greenhouse inventory focused within the city boundaries wouldn’t detect that. The same thing goes for manufactured goods that were once produced close to home, but now are shipped from distant shores. Same, too, for Seattle’s energy-intensive cement plants that have cut back on their production in recent years; Seattle’s inventory notches those cutbacks as a GHG decline, but what really matters is how much cement we consume, not how much we produce. But tracking the flow of cement into and out of the city, over the course of 15 years, would be an exercise in frustration.

    Perhaps the city would have liked to included the greenhouse impacts of materials flows in its inventory. But it’s a moot point. The data are simply unavailable—they couldn’t include it, even if they’d wanted to.

    I don’t mean to downplay the city’s accomplishment: Seattle deserves hearty congratulations for taking the time to assess itself—and for bucking the national trend towards rising emissions. Yet I have to remain a wee bit skeptical: without better measures, we can’t know if the city’s truly made the progress it’s been hoping for.