Climate TRACE database undercounts urban vehicle CO2 by 70 percent across 260 US cities, Northern Arizona University study
US cities setting climate targets may be working from numbers that are far too low. A Northern Arizona University study finds the Climate TRACE database undercounts urban car and truck CO2 by an average of 70% across 260 cities, with Indianapolis and Nashville off by over 90%.
US cities setting climate targets may be working from emissions figures that are far too low. A new study from Northern Arizona University, published in Environmental Research Letters, finds that the Climate TRACE database undercounts carbon dioxide from cars and trucks in American cities by an average of 70 percent across 260 cities. In Indianapolis and Nashville the gap exceeded 90 percent. Climate TRACE, a global emissions-tracking consortium co-founded by Al Gore, has been promoted as a way to give cities independent, near real time data on where their emissions come from. Researcher Kevin Gurney and his team checked its urban vehicle numbers against Vulcan, a database built in Gurney's own lab that is calibrated to official traffic counts and energy consumption and carries an uncertainty of about 14 percent. The differences between the two were far larger than that margin. The reason it matters: many local governments use inventories like these to set baselines, allocate budgets, and measure whether their climate policies are working. If on road emissions in a city are recorded at a fraction of their real level, decisions built on those numbers start from a flawed baseline. Gurney notes that when the vehicle findings are combined with an earlier study of Climate TRACE power plant data, the database appears to underestimate more than half of US urban fossil fuel CO2. The study does not claim the gaps are deliberate, and independent emissions tracking remains useful. What it points to is the need to validate these tools against calibrated ground truth data before cities rely on them for policy.