Seattle’s Carbon Footprint: Assessing The Assessment

The City of Seattle just released its 2008 greenhouse gas inventory, and in most of the media reports, the results get distilled down to this headline:  Seattle’s emissions are seven percent below 1990 levels. Or perhaps even further distilled to:  Seattle is meeting the Kyoto protocol. Sure sounds good, but the reality is much more mixed and messy.

The big trend that the bar chart above shows is that greenhouse gas (GHG) emissions dropped significantly from 1990 to 2005, then inched back up slightly in 2008.   (See the table below the jump for the numbers.) What has happened since 1990 that caused the net reduction in emissions even as population grew by 16 percent?  In short, the main reasons are:

  • automobile fleet efficiency rose by nine percent, which offset much of the increase in vehicle miles traveled
  • total energy use in residential buildings decreased, even as the number of households grew
  • energy use in the industrial sector decreased (though the report does not say how much of this may be due to a decline in industrial activity)
  • the GHG emissions factor for Seattle’s electricity is less than half of what it was in 1990

There’s a lot buried in those four bullets, too much for one post. The second point is the most unambiguous  success story for Seattle.

But the last point highlights a key Seattle idiosyncrasy that is critical to honestly assessing our carbon footprint:  89 percent of our electricity is carbon-free hydropower.  And since transportation uses very little electricity, for Seattle the blue pieces of pie become much bigger in the chart below.  For the U.S. as a whole, transportation accounts for only about a third of GHG emissions.

Although Seattle City Light (SCL) is technically carbon-neutral, the Seattle inventory attributes a small amount of GHG emissions to electricity use—for 2008, the report assumes an emissions factor for  Seattle that is a mere three percent of the U.S. average. SCL has reduced their emissions factor over the past decade or so by shifting their fuel mix from fossil fuels to renewable sources such as wind, and by purchasing carbon offsets.  Thus, even if electrical energy use had remained constant since 1990, the inventory would have shown a decrease in emissions.

It’s great that Seattle has access to low-carbon electricity, but unfortunately that fact can also lead to misperceptions about our current status and where we should be focusing future efforts. For one thing, it’s not exactly fair for Seattle to tout its low carbon footprint compared to other cities when the main reason for it is that we happen be located near some big hydropower dams that were built before anyone even knew what a global greenhouse gas was.

Just because electricity consumption in Seattle produces relatively little GHGs, we should be trying to reduce electricity use just as much as any other city for two reasons:  (1) the electricity grid is regional, and every clean kWh that’s not used here in Seattle is a clean kWh that becomes available somewhere else, and (2) our hydropower is maxed out, and global warming is expected to decrease capacity as mountain snowpack is reduced.  Furthermore, if we hope to start using electric cars on any significant scale, all that electricity has to come from somewhere.

The regional nature of electricity underscores the complexities involved with any attempt at a truly comprehensive GHG inventory for a specific area:  the factors that drive GHG emissions cross boundaries—a city gives and takes from a much larger surrounding system—effectively the entire planet, in fact.  And this presents a major challenge to the viability of city-specific goals, such as the recently proposed goal to make Seattle carbon-neutral by 2030.  We don’t yet know how that would even be defined, much less measured accurately.

But the Seattle inventory is a great start at “measuring what matters.”  It captures most of the major sources, and we can build on it.  Below are some random ideas on what it’s missing, the unknowns, possible improvements, etc:

  • How we account for road travel across city limits?  Currently only VMTs within the city are counted.    Consider the example of a bedroom suburb where most commuters work elsewhere.  Such a community should bear some of the responsibility for the emissions produced by residents who have to travel outside community boundaries to meet the daily needs of their lives.
  • Food systems are a major source of GHGs—meat production alone produces and estimated 18 percent of global emissions.  Much of the emissions associated with food systems is captured in the standard sectors, but the bulk of food production and transport occurs outside a typical city’s boundaries.  How would city full of a “locavore” vegetarians get due credit for the associated GHG reductions?
  • The consumer products we devour require raw materials, processing, transport, and disposal, all of which produce emissions.  Again, how do we account for the fact that most of all that happens outside the city?  And how do we divide the responsibility for emissions between those who profit from the manufacture and sale of a product, and the end consumer of that product?
  • The construction of infrastructure and buildings produces GHG emissions—a.k.a. “embodied carbon”—much of which is associated with materials that are typically brought in from far afield.  Also, the existing built environment represents an embodied carbon “bank” that we effectively draw against when we demolish existing structures.  The full embodied carbon impact of development needs to be a part of the inventory.
  • Carbon offsets are a worthwhile strategy, but I believe they should not be included in GHG inventories, because they are analogous to handing the problem to someone else, and they also can mask the data that matter most—actual emissions.
  • And lastly, how do make sure that focusing on GHGs doesn’t cause us to neglect other related impacts, such as how our Pacific Northwest hydropower dams have decimated what were not long ago the largest salmon runs on the planet.

The above points highlight that the establishment of a defensible inventory methodology is as challenge commensurate with the infinitely messiness of human systems.  But it’s about time we got busy understanding our mess.


GHG data table after the jump…

48 Responses to “Seattle’s Carbon Footprint: Assessing The Assessment”

  1. Wells

    The percentages of GHG emissions for ‘air’ and ‘marine/rail’ appeared to be switched either in Table 1 or in the pie chart and graph.

    I’d say reducing VMT is goal #1. That should include increasing mass transit use. Improve and expand the trolleybus system before building more streetcar lines. And as for Link LRT, I still say expansions south and east would be much more productive than the tunnel to UW, but the elite want their rail line built first at any cost, and lesser Seattlers are easily bamboozled by wicked witches cooing “Poppies poppies, sleep, sleep.”

  2. Dr. Density

    Thanks Dan for outlining the missing elements in the equation. I think your right on regarding the deeper issues of embodied energy, habitat loss and our hugely impactful diet.

    We have shown good progress, especially since the cities population has grown in this period. Maybe the metric should be defined per person rather than as a city total. But before we start patting ourselves on the back these deeper issues should be accounted for along with true commute driving patterns…doing all this regionally would tell us more and it would likely not look so pretty.

    It’s also nice to see that the “buildings create over 40%…” myth many eager architects like to proclaim is represented here as 21%. That is still a lot and architects/buildings still have a huge role to play in shaping more compact, transit supported and complete walkable communities. I wonder if our mild climate and our aggressive energy codes helped bring that number down against a national average?

    RE Comment #1 by Wells above regarding Streetcars: Don’t forget ee have a fully funded streetcar for 1st Hill about ready to build. Leveraging that investment a bit further would be a good idea by connecting the new line to the existing SLU line via 1st Avenue and Stewart Street. It could be the salvation of Pioneer Square. Streetcars, LRT, BRT, trolley buses and bike/ped system improvements should all be dancing together as important players with different roles in this unfolding, less car dominant, drama.

  3. Wells

    Well Dr Density, I agree the transit modes should work together, but whoever is pulling Metro’s strings lately wants all the overhead trolleybus wire removed, starting with 1st Ave. The SLU Streetcar should reach near Pike Place Market to improve ridership, but I’ve always figured running one track westbound on Seneca to either 1st or 2nd Ave and then returning on Pike and 6th would best serve the Westlake Mall area.

    What about that oversight, Dan? The figures are screwed up backwards somewhere.

  4. dan cortland

    Given the subtotals, etc. in the table, the pie chart has the error (unless the numbers are really fubar).

  5. Wells

    Me thinks somebody wanted GHG emissions of air travel to look better than it is in reality, like when Fox News reports some scandal involving a republican offical and inserts ‘Dem’ next to their name. I’m sure Boeing will consider the error an oversight, for sure, like, yeah…

  6. dan bertolet

    @3 and @4, yes the pie chart has the error – the air and rail labels are switched. I copied the charts out of the City’s report.

    @2: 40% is no myth — that’s the typical average for the U.S. The main reason it is lower in Seattle is because of our low-carbon electricity, not because our buildings are that much more efficient than any other city’s. The same effect makes the relative size of industrial pie slice smaller too.

  7. Wells

    This link is to Greg Nickels ridiculously disappointing op/ed in the Times about reducing CO2 emissions. He just doesn’t get it or something. Who knows what he’s really up to? – no good if you ask me.

  8. Joshua Daniel Franklin

    All the interconnectedness makes my head come close to exploding, but I can’t help notice that the flip side of the bedroom suburb is the lack of residential development in urban centers. Taking the long view, Blume and Clise with their “Easy access to I-5″ are looking nearly as bad as BIAW.

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  11. Pete Erickson

    Dan mentions how Seattle’s inventory doesn’t include the embodied emissions associated with food, consumer products, and buildings. These are indeed big sources of emissions that Seattle residents are partly (if not entirely) responsible for — at least as big as the “official” inventory of 4 million tons CO2e. As a first order approximation of some of these categories, I ran some numbers based on consumer spending data for the region (from the federal BLS), life-cycle emissions studies (from Carnegie Mellon’s, and Seattle’s population, and came up with about 2.7 million tons CO2e for producing and transporting food to us, 1.2 million tons for household furnishings, 0.8 tons for apparel, and 0.4 million tons for new motor vehicles.* Together these add to 4.1 million tons, nearly as big as Seattle’s official GHG inventory, and nearly all of these emissions occur outside of Seattle’s city limits, most of them outside the state, and a good bit outside the country.

    As to Dan’s point about “locavore vegetarians” — meat is indeed a big source of food-related emissions (the biggest single category in the 2.7 million ton estimate above), but transportation — a source of emissions often cited as a reason to eat local — is only about 10% of food’s life-cycle emissions. (The exception is food that is air-freighted here – air freight is very emissions intensive) By contrast, the big sources of food’s life-cycle emissions are in producing it (e.g., emissions from fertilizers, energy used in growing or processing), and so, for example, highly emissions intensive local food (e.g., that grown in heated greenhouses in winter or highly processed) may be more emissions intensive than, say, vegetables from California.

    *The numbers I quote here are from a study I worked on last year for the City Council.

  12. Pete Erickson

    Oops, in my previous comment I referenced total official emissions of 4 million tons CO2e. I was thinking too early in the morning! That was only the transportation emissions total inventory (as in the table above) is more like 7 million tons CO2e.

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    Because we run our city on hydroelectricity and live in a mild climate, Seattle’s biggest problem is cars. Cars and trucks are the largest source of our greenhouse gas emissions. Our city’s auto-dependence is often treated as a fact of nature by older commentators, and when they acknowledge the problem of auto emissions at all, they tend to claim electric cars will fix the problem.

    Unfortunately, electric cars won’t solve auto emissions, and won’t even come close to solving the massive non-tailpipe auto-related emissions that come from road building and other auto infrastructure, air- and water-pollution, increased health care costs and so on.

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  30. Derik Andreoli

    Here’s a thought on assigning carbon and other GHG emissions to transportation. 30% of all cement produced was used to construct roads. Yet, cement production falls into the industry category.

    And all those diesel and diesel electric pieces of equipment that are used to build and maintain roads also fall in to the industry category.

    I believe that these categories are very misleading and under-represent the transportation impact.

    Consider this: if we reduce VMT, we will reduce the need for new roads and road maintenance. This is a multiplier effect that good transportation policy could have.

    Now a bigger critique. We should be measuring the phenomenon from both a supply and demand perspective. If we offshore the production of steel, our carbon footprint goes down. If we consume that steel locally, though, we should account for the embodied carbon and energy, etc. in our impacts.

    How unfair is it for us to offshore production of energy intensive manufacturing while we move to an ‘information economy’ (which, BTW, is more energy intensive than most think) and then turn around and accuse China of polluting the commons while serving our consumption patterns.

    carbon footprints should be measured by consumption not production.

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