Where Do Our Carbon Emissions Come From, Anyway?

What makes up the bulk of Seattle’s carbon footprint? It’s not what you think.
Bonneville Dam, Columbia River Photo by Sam Beebe

The Columbia River in Washington state powers dams for the Bonneville Power Administration. At the end of the 1990s, Seattle's electricity was already virtually carbon free because of its use of hydro-power. 

Photo by Sam Beebe

Richard Conlin is president of Seattle's City Council, which is overseeing the city's effort to become the first carbon neutral city in the United States. He blogs about what reaching that goal really means for YES! Magazine.

Before the City Council can develop a work plan for a carbon (climate) neutral Seattle, we have to determine where our carbon emissions actually come from. This is actually a tough question. It is easy to point at particular sources and agree that they lead to carbon emissions (like coal plants or automobile exhaust pipes). It’s also easy to agree that reducing these sources would be a good thing. 

But if you are aiming at a truly carbon neutral city, it is important to understand how much carbon comes from different sources. Only with that understanding will we be able to both set priorities for action—and know that what we are doing actually addresses the whole spectrum of critical issues. Of course, even if you have correctly identified the carbon sources that you must deal with, there can still be difficult and challenging discussions about what the best strategy is to actually achieve the reduction goal—but that is the topic for future posts. The science of inventorying carbon emissions has made great progress over the last few years. Seattle has been on the cutting edge of that science, and we completed a review of our emissions in 2005 and updated it in 2008. With one major caveat, the issue of embedded carbon in products, this inventory provides excellent guidance for our work.

So, what did we discover? First, that Seattle’s emissions pattern is unique. A huge percentage of carbon emissions around the country and the world come from burning fossil fuels to produce electricity. Thanks to the foresight of previous generations, who built dams for Seattle City Light, our public electric utility, on the Skagit and Pend Oreille Rivers and joined the Bonneville Power Administration in building dams on the Columbia River system, Seattle’s electricity was already virtually carbon free at the end of the 1990s. Seattle did own a share of the Centralia Coal Plant, but we sold that ten years ago as the key step to becoming a completely carbon neutral utility. Seattle still purchases a very small amount of electricity from fossil sources to meet peak demands, but City Light fully mitigates that by purchasing carbon credit.

That means emissions from transportation sources are more significant in Seattle, and present the greatest opportunity for carbon reduction. Transportation accounts for 62 percent of Seattle’s emissions.

People often assume that means cars are the culprit, but cars and light trucks only account for 20 percent of transportation emissions. Trucks and buses are another 20 percent, and air travel another 20 percent, with the remainder being marine and rail. All of these are, of course, critical and major targets for carbon reduction, but a strategy that focuses on the automobile will not get the job done. In fact, automobile emissions increased by only 6 percent between 1990 and 2008, while air travel emissions increased by 7 percent and truck emissions by 16 percent, for an overall increase from transportation sources of 11 percent.

There is still a huge opportunity in the built environment. And we need a more sophisticated approach to industrial emissions if we are going to honestly achieve our carbon goals.

Buildings are the next largest contributor, producing another 21 percent of emissions. We have made great progress in cutting emissions from buildings, reducing them by 9 percent between 1990 and 2008, with the biggest progress in the residential sector, down by 17 percent.

The big surprise is industry. The 17 percent of carbon emissions produced by industry is a much smaller percentage than it was in 1990, as industrial emissions were cut by 30 percent between 1990 and 2008.

And this is where the major caveat comes in. Part of the reason that industry is down from 1990 is because of increased efficiencies and other real progress. But another factor is that industrial production of products that we use has shifted out of the City—and to do a true carbon neutral strategy, we have to count those as well.

So what are the key lessons from this accounting? Transportation is our biggest carbon issue—but that means a lot more than automobiles. There is still a huge opportunity in the built environment. And we need a more sophisticated approach to industrial emissions if we are going to honestly achieve our carbon goals.

Next: How the EPA’s work can inform our approach to including carbon related to the products we buy—and why non-transportation strategies are as important as those related to transportation.


  • It doesn't have to be the end of the world. Buildings, electricity production, transportation, and food and forestry contribute the bulk of greenhouse gases. But climate-friendly options are ready.

  • Meet the Joneses. They are your average U.S. energy consumer. And they decide to do their part. Watch how they go carbon neutral in a decade… and then try it yourself.
  • from Richard Conlin's blog about Seattle's effort to go carbon neutral.
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