I have been blogging on greenhouse gas inventories conducted in the State of Missouri. As far as I can tell, 10 GHG inventories have been conducted, spanning the years from 1990 to 2009 (two more are about to be published). They include the State of Missouri, St. Louis County, and the cities of St. Louis, Kansas City, Columbia, Creve Coeur, Kirkwood, Clayton, Richmond Heights, and Lee’s Summit. At right is a timeline for the series of inventories, and previous posts in this blog summarize the main findings of each.
There are problems in comparing emissions between jurisdictions. Places are very different. For instance, Missouri is a large state with a great deal of rural area, much of it mountainous forest, while Clayton is a small municipality with a dense, high-rise commercial district. Some areas are industrial centers, others have no industry at all. In addition, the inventories have studied baseline years ranging from 1990 to 2009. Emissions depend mostly on energy consumption, and energy consumption varies from year-to-year with economic conditions, with changes in energy efficiency, and with the weather.
Still, human nature begs for comparison, even if the comparisons are somewhat problematic. At the very least, perhaps comparison can bring to light differences between communities that may not be obvious on the surface, and which require explanation. No such study exists, so instead, I will construct a “back-of-the-envelope” comparison here.
To make this comparison, it was first necessary to adjust the results for the State of Missouri and Columbia from short tons to metric tons.
It makes no sense to directly compare the total emissions of states, counties, and municipalities: the differences in scale would make the comparisons ridiculous. However, there are several factors that express the scale of a jurisdiction. Three are land area, population, and economic activity. Comparing GHG emissions on a per square mile basis, on a per capita basis, or on a per unit of economic activity basis may be more appropriate, canceling out differences in scale.
The land area of a state, county, or municipality is easy to find. The population of a given jurisdiction in a given year is also relatively easy to find. GHG emissions per unit of economic activity may be the most relevant of all, however it is not so easy to find. What would be wanted would be the total economic product for the jurisdiction, something equivalent to what Gross Domestic Product represents for the entire USA. Domestic product for the 50 states is available, and I have used that metric to compare Missouri to other states (Comparing GHG Emissions Across States), but I have not been able to find it for counties or municipalities.
In reporting per capita emissions, some of the GHG inventories appear to have used population estimates adjusted from those in tables published by the Census Bureau. Though I accepted the results from each inventory when I reported on it, here I thought it best to minimize this source of change between inventories, using population estimates from the appropriate Census Bureau table as described below. As a result, the per capita emission amounts here may vary from those reported in the posts on the individual GHG inventories.
The first graph at right shows per capita emissions for the nine jurisdictions. The jurisdiction and the baseline year for which the inventory were conducted are shown on the bottom. Except for one jurisdiction, total per capita emissions varied between 20 and 30 metric tons of carbon dioxide equivalent (MTCO2e) for each of the jurisdictions. In these communities, people emitted similar amounts of GHG, irrespective of which community they lived in. The emissions for the community depended to a large extent on the size of the population.
The one exception to this rule was Creve Coeur, where the per capita emissions were much higher. Because this is an outlier, I have double-checked, and the finding seems to be a correct representation of what is contained in the GHG inventory report. The following analysis may help to explain why.
Clayton and Creve Coeur have particularly large per capita commercial emissions. They are probably the two jurisdictions that, compared to their residential population, serve as the largest commercial centers. Their population probably increases the most during the day. If one calculated per capita emissions by using daytime population instead of residential population, their commercial emissions might not seem so large.
Creve Coeur and Richmond Heights have the largest per capita transportation emissions. I think transportation emissions are a function of whether important transportation arteries traverse the jurisdiction, and whether the jurisdiction serves as a transportation destination for workers or shoppers. Creve Coeur and Richmond Heights are both.
Creve Coeur and St. Louis County have the largest per capita residential emissions, and the pattern between jurisdictions is somewhat unexpected. Residential emissions are probably a function of the energy efficiency of buildings, their size, and the amount of electronic equipment used therein. It would be interesting to know what might make residences in Creve Coeur or St. Louis County high on these factors compared to, say, the residences in Clayton or Kirkwood.
Thus, Creve Coeur may have the highest per capita emissions because it is high in all three, while the other jurisdictions are high in only one or two.
The second graph at right shows GHG emissions per square mile of land area for the nine Missouri jurisdictions. These findings vary widely, perhaps suggesting that GHG emissions are only slightly a function of the geographic size of a jurisdiction. One finding worth pointing out, however, is that the State of Missouri’s emissions per square mile were very small compared to the other jurisdictions, an intuitive finding given that Missouri contains vast areas of farmland and forest, while all of the smaller jurisdictions were developed urban and suburban locations.
Clayton and the City of St. Louis have relatively large commercial emissions per square mile. This tells us that, compared to the other jurisdictions, they are relatively small compared to the size of their commercial sectors, something that would be obvious to anybody who had visited either. Richmond Heights has relatively high transportation emissions per square mile. This tells us that, compared to the others, it is small, but a crossroads for several well used transportation routes, again something that would be obvious to anybody who had visited.
Missouri studied its GHG emissions in 1990 and 1996. Since then, however, the inventory does not appear to have been updated. It has been almost 17 years, a great deal has changed, and a new update would be welcome. Until then, the closest I have found is a time series published by the EPA concerning GHG emissions from combustion of fossil fuel. I will do a future post on this time series. The other inventories, or their most recent updates, are all less than 10 years old.
Missouri population is from Part 1. Population of the United States and Each State: 1790-1990, http://www.census.gov/population/www/censusdata/Population_Part1.xls.
County populations are from Table 1. Annual Estimates of the Resident Population for Counties of Missouri: April 1, 2000 to July 1, 2009, http://www.census.gov/popest/data/counties/totals/2009/tables/CO-EST2009-01-01.xls.
Municipal populations are from Table 4. Annual Estimates of the Resident Population for Incorporated Places in Missouri: April 1, 2000 to July 1, 2009, https://www.census.gov/popest/data/cities/totals/2009/SUB-EST2009-4.html.
Geographic areas are from the Wikipedia article for each location.