The New York Times recently ran an excellent feature on Portland’s efforts to curb emissions while still building highways:

But despite Portland’s efforts, the number of cars and trucks on its roads has kept rising as the city and its suburbs have grown — along with tailpipe pollution that is warming the planet. While Portland has set ambitious climate goals, the city is not on track to meet its targets, largely because emissions from transportation remain stubbornly high.

Now the city faces a fresh challenge: To deal with traffic jams, state officials want to expand several major highways around Portland. Critics say that will only increase pollution from cars and trucks at a time when emissions need to fall, and fast.

The overall contours will be quite familiar to Seattle residents, but the chart comparing Portland and Seattle-area emissions per capita is quite an eye-popper.

32 Replies to “Portland’s driving dilemma”

  1. My armchair observation is that the chart is probably total emissions rather than per capita emissions. The growth rates seem way to high to be per capita data and the comparison to population growth would be a bit nonsensical if it was per capita emissions.

    1. Yes. So why did emissions jump in Seattle in the 90’s and aughts but not Portland, given similar population growth?

      1. I’m guessing that Portland became a lot more dense. Portland itself is just a much bigger part of the metropolitan area than it was in 1990. The same thing happened in Seattle, but our big jump occurred during the economic downturn (since roughly 2010). There is a very strong correlation between density and emissions, so that would explain it. It would be interesting to see a chart comparing the city population to the metropolitan area for all three cities during this period (as a very rough measurement of increasing density).

        What I don’t get is the numbers from the last few years . All three of the cities saw their emissions grow faster than their population. Cheap gas, maybe?

    2. Especially when vehicle miles traveled flattened in the aughts, and downtown car commutes shrank to 30%.

      I don’t understand the difference between total and per-capital emissions. If you divide the total emissions by the population size, it shouldn’t change the curve. Does total emissions include non-transportation uses?

      Seattle’s transit ridership per capita is also higher than Portland’s and has been for decades.

      So if it says Seattle’s emissions grew faster, it sounds like either that’s inaccurate, or Seattle’s cars inexplicably got dirtier.

      1. Hopefully my comment below clarified what is going on. They use 1990 as the baseline. That is why all cities have the same numbers at that point (even though obviously they didn’t have the same population or emissions). For each city, the grey line measures the change in population, while the red line measures the change in emissions. As I wrote below, it is quite possible that Seattle still emits less per capita than Portland, it is just that Portland has improved since then, while we haven’t.

    3. I think the wording was misleading. I believe that the red line is total emissions, while the grey line is population. You really can’t see the emissions per capita, but you see the change in emissions per capita since 1990 by comparing the two lines.

      Since that time, Portland has been on the “right” side of things for a while now, while Seattle and San Antonio have not. It is quite possible that Seattle was better in 1990, and Portland just caught up in the 90s. Either way though, it is clear that Seattle hasn’t been getting better since then, while Portland made great progress during the 90s and into the new century, but has slipped back a bit the last few years. San Antonio has been doing especially bad.

      Looking at emissions per capita would be interesting as well.

  2. The correlation between density and carbon emissions mostly has to do with requiring suburban workers to commute to urban offices to work.

    Eliminate the commute and you eliminate the differential in carbon emissions per sf. Pre pandemic folks like Biden and Inslee saw the EV as the solution, (especially with smart metering and using the EV battery as storage), and in the long term I agree. But why more climate advocates are not DEMANDING WFH options I have no idea. That is zero emissions immediately.

    At the same time we on the Eastside get our electricity from PSE which is mostly coal and gas generated. The situation with Lake Meade suggests hydropower will be very sensitive to climate change, and Ukraine is a cautionary tale about having a single energy source as Germany and Japan look to return to nuclear power.

    Will citizens voluntarily do things they don’t want to like move to a small multi-family unit in an urban center — like Bellevue as jobs move out of Seattle — or can afford to, or take transit instead of driving? No. The best solutions to combat global warming are those like WFH and EV’s that eliminate emissions but require no sacrifice of the user.

    Few issues have been more co-opted than global warming, some for money and some for ideology. But if carbon emissions are going to come down it won’t be because citizens were forced to do what they don’t want to do. In that case they will just elect f different politicians .

    1. Work from home is not necessarily net zero emissions. Not even necessarily a reduction in emissions, I would argue, as most vehicle miles traveled are not work commuting. One might just run more errands during the day that require a car, vs. walking somewhere near the office (or a shorter, quick drive) instead. One might order Uber Eats or drive somewhere to get takeout, instead of packing a lunch or walking to the cafe or cafeteria downstairs to get a bite. (Don’t fall for the accounting trick where you shift your emissions to others and call it Net Zero!) One thing the lockdowns showed us–people by and large won’t simply cook meals at home, even when they have more time to do so. Finally, many people have moved to areas that are more car dependent and require more vehicle miles for the same errands and tasks (and more emissions to provide city services). It’s kind of another form of induced demand. No wonder, traffic congestion is pretty much back to pre-pandemic levels, while many offices are still in a remote or hybrid situation.

      1. On top of all of the above, working from home significantly increases home energy use, as lights are on all day, and the home must be heated or cooled to a more comfortable temperature when somebody is home vs. away in an office. By contrast, unless every single person works from home allowing the office to outright close, the office’s energy use doesn’t go down when fewer people are in it. Even 1/3rs full, the office still has to be heated and cooled, and the lights kept on.

        Anecdotally, my home energy use (particularly air conditioning during summer months) went up dramatically when I was working from home vs. in the office. It’s a lot easier to let your home heat up to 80 degrees during the day when you’re not there.

      2. I wasn’t suggesting WFH makes someone carbon free. Just that WFH eliminates the carbon emissions from the commute, and makes suburban and urban living closer in per capita emissions.

        Urban dwellers have just as many deliveries from Amazon, UPS and door dash, and probably more since suburbanites tend to do their grocery shopping in bulk and cook at home more. I have friends who lived downtown Seattle and Bellevue and they Uber everywhere.

        WFH also avoids duplicating spaces, an office and work space. Even when at an office a house is still heated and lighted, especially if a spouse or kids are at home. Easier to shut down unneeded office space.

        Still, EV’s — including delivery and Uber vehicles — and things like heat pumps help reduce emissions with little sacrifice except perhaps cost, depending on how green the electricity. I have friends who have SFH’s with solar panels and EV’s with smart metering (plus yards that help capture carbon) and they are truly carbon neural. In suburbia.

        Density and zoning are just another group (builders) co-opting global warming, not unlike transit.

    2. The correlation between density and carbon emissions mostly has to do with requiring suburban workers to commute to urban offices to work.

      Citation please!

      I believe there is no basis for your statement. Allow me to quote from this paper, from the University of Texas:

      All studies reviewed for this paper show a strong inverse correlation between the density of a community, energy use and greenhouse gas emissions produced. Common to each study is the understanding that higher density developments result in both the reduction of greenhouse gas emissions and energy use. Of this overall reduction, the studies agree that 45 to 50 percent of this reduction would be the result of energy efficiencies (such as district heating of buildings in both the residential and commercial sectors), another 45 to 50 percent would be the result of the reduction of vehicular travel, and the last 3 to 5 percent would be the result of the reduction of municipal infrastructure support.

      I can go on, but you can read the paper yourself (I recommend it — it is pretty short and easy to read). A few things worth emphasizing:

      1) It isn’t just transportation. Buildings in denser areas are more energy efficient.
      2) It isn’t just that people switch to using public transportation. People walk and ride their bike more.
      3) It isn’t just mode. It is distance as well.
      4) It isn’t just commuting. To quote from the study again: the studies find that shopping trips are most greatly influenced by increased density. In the final conclusion it suggested [reducing] the distances required to travel between work, home and basic services, specifically in suburban areas (Norman et al.).

      In a world where we were overflowing with excess clean electric energy, and there was no environmental cost to operating more vehicles, lack of density would not increase greenhouse emissions (at least not to a significant degree)*. But we don’t live in that world. Increasing energy efficiency is one of the key elements to reducing greenhouse emissions. Increasing density — for several reasons — is a big part of that.

      * There is an environmental cost to sprawl, but that is largely local, not global.


        As I noted WFH is one tool to reduce carbon emissions. Whether on a bus or in a car.

        EV’s, electric buses, heat pumps, solar panels. Smart metering are other tools.

        The key is these tools are achievable because they don’t ask citizens to change their lives. People who prefer an urban multi-family housing arrangement don’t do it for carbon savings. Same with someone who prefers a less dense living experience.

        I read the article, and about a dozen others that all begin to question the linearity between density and carbon emissions.

        But since transitioning folks from cars to transit or from SFH to urban multi-family housing has proven virtually impossible (and look at the posters on this blog who live in SFH: is Pinehust “dense” according to these articles? Of course not) it makes more sense to attack what is actually causing carbon emissions, like combustion engines, generating electricity from coal like PSE, an ability to store electricity, a heat pump, better windows and insulation, and so on.

        There can be a million urban planning papers claiming there is a direct linearity between “population density” and carbon emissions but so what? Is the plan to upzone the Sammamish Plateau to reduce emissions? Or condemn the Eastside and force residents to move to Seattle and live in apartments. Or like the developers claimed upzone downtown Bellevue to 660’? How much carbon is that development saving? None, although it is likely the densest living by far in the entire region.

        Find out the cause of the emissions and find ways to eliminate them without asking citizens to do what they don’t want to do. We can address carbon emissions without changing housing desires.

      2. IDaniel, there are lots of reasons people live in suburban areas that are structural and not related to “housing desires,” of which the familiar topic of zoning is but one consideration.

        Also, I find your implication that no one makes their life decisions for the environment to be both cynical and untrue. Who are you to generalize about others’ motives?

      3. Actually Andrew, I would think the top two reasons folks live in the suburbs are public safety and public schools. There are plenty of SFH neighborhoods in Seattle, and plenty of multi-family housing on the Eastside. IMO the zoning has little to do with carbon emissions.

        I don’t know your situation and what sacrifices you have made to curb emissions. If you are served by PSE the electricity you receive is mostly carbon based. Unless you live off the grid.

        Washington State as a whole hasn’t come close to its carbon goals since the height of the recession in 2012. This suggests to me the best way to curb emissions is at the source, and there are some ways to do that without asking citizens to change behaviors.

        For example, solar panels, EV’s, LED lights, heat pumps are good steps, depending on how the electricity is generated. I have previously posted that I have friends who have solar panels on their SFH and use their EV to store and sell electricity back into the system through smart metering. Plus they have a yard that captures carbon. So despite living in suburbia their carbon footprint is less than your footprint.

        Virtue signaling won’t reduce carbon emissions. Neither will some kind of urban ideology, because zoning doesn’t cause emissions. Burning fossil fuels does.

        The idea pouring millions of tons of concrete and emitting millions of tons of carbon to build Link will help us meet our carbon goals is another fantasy.

        But transit’s goal is not to solve global warming. It is to provide transportation at a price all citizens can afford.

      4. IMO, the reason most people live in the suburbs is the same reason they live in any neighborhood – cost of housing balanced with access to jobs. Suburbs are consistently more affordable than cities on per sq foot basis, particularly when the cost of transportation is a wash.

      5. My primary problem with the premise of a lot of your posts is that EVs are not carbon-free. I don’t have a problem with photovoltaic panels. They’re great and I applaud your friend for doing so. I have an uncle with the same situation. Maybe we’re talking about the same person.

        But the idea that we can tackle global warming without asking people to change their behavior *at all* is just as much a fantasy as the idea that virtue signaling will do it (or Link for that matter, which, in alignment with most posters on this forum, I am well aware will not meet Seattle’s transportation needs, despite its large cost).

        EVs are not carbon free. That’s the key. It takes years of zero-carbon driving for an EV to pay off the debt it has of carbon *relative to a conventional automobile.* In general, any thought that consumerism is the way to solve our environmental problems ought to set off alarm bells. The solution is not, “buy a bunch of new stuff.” The solution is, do more with what we have. Dense living is more efficient. We have the land; use it! Allow people to live in apartments close to downtown or to where they need to go. Buses transport so many people relative to cars on a pound-for-pound basis. That’s doing more with less.

        And yes, re. Link, building a new elevated rail line to Fife is a kind of consumerism. It’s a big shiny that, all estimates point to, will only carry a minor proportion of trips. The problem with the US is we get big shinies instead of real, transformational change. Transformational change can happen, but we have to align big policy with what people want to do.

        The reason “housing desires” set me off, yesterday, is *many people want to live in density,* but there are structural reasons that push people towards single family homes. These are reasons like zoning, like the mortgage-interest deduction, like how roads and sewers are built and paid for in the US. If we changed these things, I fully believe we would see denser cities, rapidly.

      6. Very few things are carbon free Andrew. Even walking on pavement in a city with painted crosswalks, lighting, and crossing lights. In fact since a city is built on impervious surfaces just about nothing in it is carbon free. Even maintaining parks takes carbon.

        Mortgage interest deduction applies to any zone. We do have dense cities. Cities are where all the carbon is emitted. If the citizens wanted it we would have denser cities.

        The reality is this region was platted long ago, and private property can be developed. If suburbia inherently results in greater per capita carbon emissions does it make sense to mildly upzone these far flung areas and move more people there?

        Everyone wants less carbon (or should). But so far history suggests most are not willing to make major changes to reduce carbon, eg SUV’s.

        You can’t downzone suburbia to rural without paying FMV. These folks moved out of the city to get away from it. You can’t force them back. They don’t want to rent an apartment. You can’t ban cars, make them take a failing transit system, go to a city they think is dangerous or has bad public schools, or ban furnaces or air conditioners or appliances or flying.

        Just look at Biden scrambling to produce more oil to lower gas prices because gas prices are going to wipe out D’s in 2022. Do these sound like citizens who are willing to make major sacrifices to reduce carbon? It is why corporations and politicians like carbon goals in 2050, when they are out of office.

        America is built on the premise you build a better mousetrap. Refrigerators today use around half the electricity refrigerators used in 1970, and no one notices or wants an older refrigerator. Good thing Pres. Carter didn’t suggest reverting to the ice box, although he did recommend lowering the thermostat to 68, and look how that turned out.

        You think your urban life is more moral. Everyone thinks their life is more moral. If the goal is to reduce carbon emissions take Carter’s lesson on refrigerators, not a return to the ice box or returning to a city (Seattle) many think is failing and won’t save any carbon anyway.

      7. When we’re saying that density = lower CO2 emissions, it’s really:
        (1) square footage per person
        (2) transportation

        So density is a double whammy for top two sources of CO2 emissions — buildings and transportation. You can’t possibly believe that anyone pushing for CO2 reductions via density is co-opting climate change. It’s one of the easiest wins that we can have — and it improves so many other problems besides climate change.

        I wouldn’t even think of it as the CO2 footprint of various activities, it’s really more of the energy requirement of materials to build bigger stuff, transporting people/goods farther distances, heating/cooling bigger spaces, etc. etc. It hurts the benefits you get from green energy because you still need more energy to live in a lower density area. That’s unavoidable.

        If Tiger Mountain wasn’t a state forest it would be one of the juiciest bits of real estate in Puget Sound. Imagine how many utopian suburban homes with views could be built on that chunk of land. Maybe we should develop it in order to ease the housing crisis? We could make it a requirement that every single house be constructed with solar panels and EVs with smart metering and heat pumps. It could be the first fully carbon neutral suburban development in the United States. What could be more green than that?

      8. Daniel:
        Net carbon emissions doesn’t just have to do with production, but also absorption.

        Typical suburban development is what has happened just north of I-5 in Lacy. Several thousand acres of mixed forest and farm are turned into single family houses. There is little vegetation left, and what little is left is stuff like tiny lawns that emit more CO2 than they absorb. Driveways and rooftops don’t absorb any, but the landscape that was there was vastly better at absorbing CO2.

        Sure, some people want to live in a vacant concrete nothingness of suburbia, but if given an economic alternative, many would prefer to live where there actually is stuff near where they live.

        Gravity doesn’t magically change in Europe or Japan or Canada vs the USA. It’s only our policies that insist on only building single family housing that creates this unbalanced situation.

      9. Hmm, who to believe…the academic paper cited by RossB, or the Alliance for Virtual Offices, with over 1,200 virtual offices to boost your brand!

    3. Will citizens voluntarily do things they don’t want to like move to a small multi-family unit in an urban center — like Bellevue as jobs move out of Seattle — or can afford to, or take transit instead of driving? No.

      European cities tend to have a much higher percentage of multi-unit housing.

      Maybe if something other than single family housing were available, more people would be living in something else? Right now the current situation means single family housing is the only thing practically available.

      Seattle has done a much better job than Portland of building alternatives to single family houses.

  3. The simplest explanation for the early 1990s divergence is that the early data is junk. Note how similar the pattern is from 1995 onwards. These are modelled emissions – nobody’s directly estimating what comes out of your tailpipe – some product of estimated VMT with assumptions about emissions per mile, and there’s a wild inconsistency in inputs between 1990 and 1995.

    I’m not sure either city’s data passes the sniff test – 1995 is mostly the same people driving the same cars as 1990 in both cities, but the intensity of Seattle emissions per capita certainly didn’t double in five years vs Portland.

  4. Im wondering snout the effects of hybrids and all-battery vehicles. Their increased popularity seems to jot have Amy countering effect at all.

    Either that or VMT is greatly increased to the point that is huge! I don’t think it has ballooned that much but I could be wrong.

    1. Anecdotally, looking at cars on the road, there’s just not enough battery powered vehicles yet to make much of a dent in carbon emissions. You can see this for yourself by standing at a busy intersection for 10 minutes and counting the cars. At least 95% of them are still burning gas. What impact EVs are making is being more than offset by the trend of consumers switching away from compact cars in favor of gas guzzling pickup trucks and SUVs.

      In time, I do expect EV adoption to increase. Once we reach the point where the average everyday person knows someone who has been driving an EV for at least a few years, it will become a lot easier convincing others to switch too. Today, of course, we’re nowhere near there yet.

      (While the WA law banning sales of new gas vehicles after 2030 is laudable, I’ll believe it when I see it; I think it’s far more likely that in 2030, it gets pushed back to 2035, in 2035 to 2040, etc. Maybe by 2070, it will finally happen).

    2. Most of the major carmakers are phasing out gas cars in the 2030s or 2040s, so new ones may be gone by the time the state gets around to banning them. Automakers build for the whole world, and many other countries are ahead of the US in phasing out gas cars and their subsidies. They’re feeling the impacts of climate change and/or their oil comes from unstable dictators they want independence from.

      1. Best place to start with EV’s is delivery vehicles like Amazon, and fleet cars like rental cars that will show drivers EV’s require no sacrifice for the average non-rural driver. Plus rental fleets turn over frequently and are sold to the general public.

        The issue right now is the materials for batteries and EV parts, which I assume is impacting Metro’s efforts to go green. There just are not enough EV’s available for sale to meet demand right now.

        Between EV’s and solar panels (with smart metering that creates massive battery storage that can be sold back into the system during peak usage) we can significantly reduce emissions with little sacrifice or change for citizens, with or without WFH.

        But we need to be careful that electricity generation can meet future increased demand, because when it doesn’t utilities tend to fall back on coal.

  5. Our region has set various goals to reduce carbon and get neutral, but major projects such as Eastlink and WSB have been delayed. May be that’s actually good for our environment as the construction of another tunnel would take literally a ton of carbon, another reason to rethink that approach. Construction of the West Seattle portion may take up to 614,461 tons of carbon. Until it connects downtown directly, Sound Transit does not expect any car trip reductions. Once it does, it may only reduce carbon by about 3000 tons annually. That means this project will increase carbon, not help us meet our climate change goals.
    What else can we do? Run more buses? KCMetro already has trouble finding drivers. Can we increase ridership on our existing light rail network? How about more automated carbon free alternatives to get more people to onto light rail such as funiculars, APMs, or gondolas to connect Harborview, Belltown, West Seattle, South Seattle College, Southcenter, Bellevue College or Kent to our light rail network?

    1. When looking at the carbon impact of any large mass transit project, you have to look at where the vehicle technology will be by the time it opens, not where it is today. If a line is not scheduled to open for another 20-30 years and the cars it takes off the road are 60% electric, rather than 3%, all of a sudden, its carbon impact doesn’t seem so much anymore, especially after considering the huge amount of carbon emitting up front, constructing the line in the first place.

      That’s not to say that mass transit should not be built, only that the purpose used to justify it needs to be something other than carbon emissions. For example, providing a congestion-free option to move large numbers of people quickly, reducing financial barriers to be able to move around the region, or supporting walkable neighborhoods by allowing them to function without providing so much car capacity as to make the neighborhoods no longer walkable anymore.

      This is especially true with inter-city rail projects, where the up-front costs and carbon emissions are even higher, the eventual opening, even further out into the future, and the annual ridership much lower (because people travel between cities much less often – by any means – than they travel within them). By the time a high speed rail line finally opens between Los Angeles and San Francisco, for example, even airplanes between the two cities might be electric.

      1. Certainly many parts of ST3 won’t be open in 2035, when new cars will likely only be sold with electric power. The CO2 argument won’t be very powerful. Also electric cars are quieter so road noise will be softer too.

        The cause for rail transit will be to offer convenience, avoidance of congestion and maybe cost saving (as electric cars likely will sell at higher prices and will not lose value as used cars will last longer than those with gasoline power).

        That’s not to say that global warming issues wont exist. It’s going to dominate the world discussion as extreme weather and sea level rise increasingly threaten many. I just think that a more likely outcome will be for other actions to emerge as more important.

  6. In every U.S. metropolitan area, single family houses (usually detached) are the dominant form of housing. There are many millions of them. Nobody’s being forced to live in apartments. In fact, people often feel forced to buy single family houses because there aren’t good alternatives. The question, especially in a quickly growing region like Seattle, is whether new housing will focus on density or sprawl.

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