This story is a lot more complex and nuanced than the headline would lead you to believe.
It may come as no surprise to anyone who has spent time on Houston’s roads at rush hour that just over half of all the city’s reported greenhouse gas emissions come directly from traffic. This is the greatest share among the largest U.S. cities that volunteered emissions information to the Carbon Disclosure Project (CDP).
The data was collected by survey in partnership with CDP and ICLEI – Local Governments for Sustainability, and contains self-reported amounts of methane, nitrous oxide and carbon dioxide as well as other notable greenhouse gasses and carcinogens. The data is broken out by 51 categories submitted by more than 1,100 cities, states and municipalities around the world.
Data like this is considered primarily a preparedness tool according to Katie Walsh, head of cities, states, regions and public authorities for CDP’s North America division. By compiling and submitting this data and by answering questions about climate change mitigation policies, Walsh says cities get a chance to assess where they stand and where they need to go to effectively reduce greenhouse gas emissions.
In a city reporting vehicle-oriented emissions as high as Houston’s, local governments and nonprofits can use that data to design initiatives that target specific needs. One example, Evolve Houston, which grew out of the city’s climate action plan, is working to reduce carbon emissions from personal vehicles by pushing electric vehicle adoption and infrastructure.
The 2022 CDP submission marks the 11th year Houston has reported data to the CDP.
Stationary emitters like homes and businesses, as well as power plants, typically make up the lion’s share of emissions in cities, according to CDP city-level data. But despite a large oil and gas industry and booming housing developments, this is not true for Houston – traffic is king.
Although traffic is undoubtedly a top greenhouse gas emitter across the nation, its spot at No. 1 in Houston may have more to do with how well it’s tracked and how poorly other sources are monitored. For example, emissions from the Port of Houston – one of the largest ports in the US, mover of 55 million tons of annual cargo and representative of 20.6 percent of Texas’ total gross domestic product – are not accounted for in the city’s reporting. The city hopes to include emissions from “waterborne navigation” in future reports.
Looking at a city’s share of emissions by “sub-sectors,” which are the smallest buckets that emissions can be categorized by in the CDP data, reveals unique inventories for each city. These inventories can help city officials identify the most problematic sources of pollution as well as where they have deficiencies in emissions reporting.
There’s more, so read the rest. The main thing I took away from it is that categorizing the data can be helpful in telling cities where to prioritize efforts, but there’s a lot of subjectiveness in it, which limits the usefulness of those categories. Cities only have control over so much of the emissions in their vicinity as well. Having good data is helpful, but getting good data is easier said than done, and there’s a lot of room for improvement now. But it’s better than nothing.
