Study Finds Major Errors in Climate TRACE Emissions Database

A new study from Northern Arizona University (NAU) indicates significant undercounting of urban vehicle carbon dioxide emissions in the Climate TRACE database. This database is a global greenhouse gas emissions consortium co-founded by former Vice President Al Gore. Researchers found that the database underestimates urban vehicle CO2 emissions by an average of 70 percent across 260 United States cities.

The findings, published in *Environmental Research Letters*, highlight discrepancies that raise concerns about the reliability of emissions data. Kevin Gurney, a professor at NAU's School of Informatics, Computing, and Cyber Systems, led the study. The research focused on carbon dioxide emissions from cars and trucks.

To assess the Climate TRACE estimates, Gurney and his team compared them with data from Vulcan. Vulcan is an independent emissions database developed by Gurney's laboratory. It uses official traffic records and energy consumption data for calibration. The comparison revealed that Climate TRACE CO2 emissions were, on average, 70 percent lower than those in the Vulcan database. Some individual cities, such as Indianapolis and Nashville, showed discrepancies exceeding 90 percent.

This study follows an earlier investigation that identified similar issues in Climate TRACE estimates for power plants. The researchers suggest that the underestimation may extend beyond the United States and could affect Climate TRACE data globally. They also expressed concerns about other aspects of the database that may require further scrutiny.

The researchers acknowledge the potential of artificial intelligence (AI) for monitoring environmental conditions and generating emissions estimates. However, they emphasize the importance of strong scientific standards. Transparency, expert review, and rigorous scientific methods are essential to ensure accurate and trustworthy emissions data. Reliable greenhouse gas measurements are fundamental for effective climate policies.

Professor Gurney has dedicated over two decades to developing standardized methods for measuring greenhouse gas emissions. His Vulcan and Hestia projects quantify and visualize emissions across the United States. These systems help identify emissions hotspots and support targeted pollution reduction strategies. Gurney's work has contributed to the United Nations Climate Change Framework Convention and the Kyoto Protocol process.