Last month, I wrote about the well-intentioned but short-sighted green building ordinance under consideration by the city that would have required costly upgrades for energy efficiency in the renovation of older homes. In the article, I wrote that while older homes indeed use more energy, these emissions pale in comparison to automobile emissions from newer areas where driving is required. Rather than saddle potential homeowners with more costs, it makes more sense to encourage more people to live in older neighborhoods.
Last week, research released by UC Berkeley’s ClimateCool Network reaffirmed this view, showing that most of Stockton’s 2013 emissions come from the outskirts, and mostly because of driving. I have reproduced the data from the paper below (click on each area to see the data), where you can see the amount of emissions the average household is responsible for by Stockton’s various zip codes, and how these emissions break down by origin (note: the zip code boundaries are approximate, as reported by the researchers. I also shortened the area of the zip codes whose area includes large swaths of land away from Stockton i.e. 95219).
As you can see, emissions rise farther out from the city’s core. In fact, homes around Downtown Stockton (95202) have the lowest emissions by far—24.6 metric tons CO2 equivalent on average. As you venture further out, Stockton’s older zip codes exhibit slightly higher emissions, and the areas on the outskirts turn out to be the city’s biggest polluters overall. Stockton’s highest polluting zip code is 95209, with homes accounting for an average of 51.2 metric tons of CO2 (the national average is 48). This shouldn’t come as a surprise, as residents of outlying areas have to drive more, thereby emitting more pollution.
As it turns out, the data from the Berkeley report confirms that driving is the main culprit for Stockton’s pollution woes. The report breaks down household emissions by the source— transportation, housing, foods, goods, and services— and the differences between Stockton zip codes are stark. Referring back to the map above, you’ll notice that transportation takes up the largest share of emissions for each zip code, with the exception of downtown. As you move further from the core, transportation emissions rise.
The information presented by the Berkeley report tells us two things. First, emissions are worst at the periphery, and largely because of transportation patterns. As I have written before, the real problem with Stockton’s air quality is linked to excessive sprawl and the driving habits it encourages. While older homes are leaky, they are close to amenities and therefore do not require as much driving, which is ultimately the main driver (pun intended) of pollution in the Central Valley. The data from Berkeley proves this point, as Stockton’s greenest zip codes are the ones closest to the city’s core. The greenest policy the city could undertake would be to focus new growth inward.
Second, if Stockton wants to get serious about cleaning the air, infill alone won’t get us there. The report’s authors conclude that even though there is a positive correlation between density and air quality, these gains vanish once you take into account the corresponding increase of suburbanization. This is of particular concern here in Stockton. Even if the city were to reach its goal of 4,000 new downtown housing units by 2020, there are still around 30,000 “paper lots” already approved by the city for development on the city’s outskirts. That doesn’t even take into account other proposed developments that developers are trying to sneak in, such as the Bear Creek East development proposed last month (though thankfully, it was voted down by the planning commission).
While we may very well see downtown housing start to take hold in the coming years, allowing sprawl to continue would easily negate any real air quality progress. Will Stockton’s city leaders show the resolve to resist new suburban homes, even in the face of a housing market recovery? I certainly hope so, because if not, its bad news for anyone breathing Central Valley air.