Highways stacked in Dallas. Credit: Adobe Stock

At COP27, a prominent climate change conference held in Egypt last November, former Vice President Al Gore showed off a new tool that can identify the climate miscreants most responsible for the planet’s warming. 

In the transportation sector, the Los Angeles and New York metropolitan areas, unsurprisingly, ranked first and second. But the Dallas metro area came in third, ahead of smog-choked Guangzhou in China and traffic-clogged Houston.

The tool, called Climate TRACE, uses satellites and artificial intelligence to calculate greenhouse gas emissions. It estimates that cars, trucks and other vehicles in the Dallas metro — which covers parts of Collin, Dallas, Denton, Rockwall and Tarrant counties — produced about 23.8 million metric tons of greenhouse gas emissions (or carbon dioxide equivalent) in 2021. Transportation in the Houston metro area, by comparison, yielded an estimated 20.4 million metric tons.

The Dallas area has about 11,500 miles of traffic lanes, with vehicles logging nearly 77.5 million miles each day, according to data from the Texas Department of Transportation. In some parts of the region, highways can stretch to 10 lanes and interchanges can stack up to three levels. The city estimates that only 3.8 percent of Dallas commuters use public transportation; the percentage is even lower for commuters in nearby suburbs.

The Climate TRACE data adds to research showing a persistent air-quality problem that endangers public health in the fast-growing North Texas region. Urban sprawl encourages the use of more and more automobiles. Clean-air advocates say stronger measures are needed to promote urban density, which would lead to shorter commutes and facilitate a more robust public transportation system.

Although the Climate TRACE findings have yet to receive the peer-review stamp of approval from the scientific community, the results echo similar analyses, the authors say.

“It did surprise me how high of a ranking we are,” said Chris Klaus, a senior program manager for the transportation department of the North Central Texas Council of Governments, which coordinates regional projects in Dallas and 15 nearby counties. The council, he said, would “look into it and see the assumptions [Climate Trace is] based on.”

Climate TRACE is different from other data sources in that it doesn’t rely on industries to report their own emissions; doesn’t have the two- to five-year lag that official reports often do; names names instead of presenting aggregated data and shows how specific sources around the world compare to one another.

A team of more than 100 people — mostly academic researchers and workers at nonprofits including the Johns Hopkins University Applied Physics Laboratory and RMI, formerly the Rocky Mountain Institute — has been building Climate TRACE since 2019. 

Scientists have used the tool to analyze emissions from the world’s largest oil and gas fields, power plants, cars and trucks in major cities and more — some 80,000 sources across 10 sectors. Transportation from the Dallas area alone ranks 59th in the world for all these sources combined.

Climate change driven by greenhouse gases already has acted as a disruptor, exacerbating everything from heat waves in Texas to wildfires in Canada and floods in Pakistan. Research shows that the destruction will become much worse if the world doesn’t reduce emissions significantly and fast.

“Our central theory of change is that if you want impact, you need to have data to support it,” said Lekha Sridhar, a policy analyst for the environmental nonprofit WattTime who worked on Climate TRACE. “The benefit of this dataset for people, not just in Dallas but anywhere, is that we now have a foundation of data to base interventions on.” 

Calculating emissions

The Climate TRACE researchers calculated their estimate for the Dallas-area transportation sector by multiplying the amount of traffic on the roads by the country’s average greenhouse-gas emission for each type of vehicle  – from motorcycles to trucks. The former is estimated using a deep-learning algorithm that is fed satellite imagery, maps and population data. The tool differentiates between gasoline and electric-powered vehicles.

It’s not an exact science. But members of the Climate TRACE team say their estimate for the Dallas area lines up well with emissions inventories that use different methods, like EDGAR, Carbon Monitor and the Energy Information Administration

Climate TRACE continues to add data, including emissions from buildings, smaller industrial sources and transportation from 10,000 more cities, which the team plans to release before COP28, this year’s climate conference, which will be held in Dubai in November.

The team decided to publish its research before it underwent peer review. Kevin Gurney, a professor at Northern Arizona University who served as an adviser on the transportation calculations, said that any data that hasn’t undergone such scrutiny should be taken with a grain of salt, though its consistency with other emissions inventories suggests it’s generally accurate. 

Jim Schermbeck, director of Downwinders at Risk
Credit: Downwinders At Risk

Researchers “pressed on getting results first, and then doing things like the peer-review process, which is lengthy,” Gurney said. “I think it’s a promising technique, and the initial results look broadly correct. But I think for more specifics, we need to do analysis of the results that have been produced.”

The city of Dallas developed its own emissions inventory and found that transportation produced about 7.1 million tons of greenhouse gases in 2019 – about 38% of emissions from all sectors, including buildings, homes and landfills. The North Central Texas Council of Governments will release an inventory this year.

A key difference between the city’s report, which estimates about two-thirds less pollution than Climate TRACE, is that its measurements were limited to Dallas proper, whereas Climate TRACE measures emissions from the entire metro area. The city’s data has Dallas as the seventh-biggest emitter of greenhouse gases in North America, behind New York City, Mexico City, Chicago, Los Angeles, Houston and Guadalajara. 

Dallas’ population is about 1.3 million, census data shows, significantly lower than, say, New York’s 8.3 million and Los Angeles’ 3.8 million.

Ozone and fine-particle pollution

In the transportation sector, greenhouse gases are only part of the problem. Tailpipe emissions also contribute to the formation of ozone, created when two pollutants, nitrogen oxides (NOx) and volatile organic compounds (VOCs), interact with sunlight and heat. Ozone can aggravate lung diseases such as asthma, emphysema and chronic bronchitis.

The American Lung Association gave Dallas County an “F” for its ozone problem this year and ranked the metro area as the 18th most polluted in the country, though air quality has improved significantly in the past two decades. More than 41,000 children and 161,000 adults have asthma in the county, a condition that makes them more vulnerable to ozone’s effects, according to the group.

The Clean Air Act amendments of 1990 tightened standards for how much ozone is legally allowed. Since then, the U.S. Environmental Protection Agency has determined that Dallas-Fort Worth is over the limit of 70 parts per billion (ppb).

Klaus, of the council of governments, said the metro area’s air quality has improved since 1990, but hasn’t kept up with EPA standards, which were updated in 1997, 2008 and 2015. 

The Dallas-Fort Worth ozone average exceeds both the 2008 and 2015 standards. Last year, the region became a “severe” violator of the 2008 standard. Industries most responsible for the pollution, such as power plants and cement manufacturers, may have to pay $45 million in fines if ozone levels don’t meet standards by the end of 2026, according to the Fort Worth Report. 

Ozone also contains harmful particulate matter, the most dangerous form of which, known as PM2.5, can go deep into the lungs and enter the bloodstream, causing health problems ranging from throat irritation to heart attacks. Dallas-Fort Worth meets the federal PM2.5 standard, but data from Dallas County shows that spikes in the pollutant align with more emergency-room visits by asthmatics. The EPA has proposed a tightening of the standard by up to 25 percent, from 12 micrograms per cubic meter to between 9 and 10 micrograms per cubic meter.

Dr. Cesar Termulo, a pediatrician at Parkland Health in Dallas, said studies have shown that people who live closer to highways experience more asthma symptoms than those who live farther away. But air quality “is usually not part of a medical history,” Termulo said. “Providers, unless they’re living in an area surrounded by factories … might not really be aware of particulate matter.”

Klaus said the council of governments has taken steps to reduce ozone, like launching anti-idling campaigns to try to get vehicles to stop running when parked and securing more than $81 million in transit-related grants from the federal government over the past five years. 

“The program is specifically for ozone, but reducing tailpipe emissions also helps with particulate matter and greenhouse gases,” he said.

‘All just rhetoric’

Misti O’Quinn began organizing for clean air in the Dallas-Fort Worth area after she discovered the link between PM2.5 and the severe asthma two of her children experience. O’Quinn, who works for the Texas chapter of the Sierra Club and Downwinders at Risk, a local environmental group, said that addressing this form of pollution may have the side benefit of combating the climate crisis, which can seem abstract.

“You’re not going to get people on board for something that they don’t see or understand how it tangibly affects their life,” she said. “People are just trying to pay bills, buy groceries and live, generally speaking.” 

Jim Schermbeck, the director of Downwinders at Risk, said the council of governments isn’t doing enough. “It’s all just rhetoric,” he said. The anti-idling campaign, for example, is voluntary and therefore unenforceable. “What is needed is to integrate this kind of thinking into actual policy — not just try to clean up the mess after you make it but to actually restructure the place so that you’re not dependent on car culture.”

Dallas released a climate plan in 2020 after holding hundreds of community meetings and receiving more than 9,000 suggestions from residents. It aims to achieve net-zero emissions by 2050, in line with the Paris Climate Agreement, meaning that for every unit of greenhouse gas the city puts into the atmosphere, it pledges to remove the same amount by, for example, planting trees or creating green spaces, both of which absorb carbon. By the city’s own estimate, however, the plan will only reduce emissions by 66% by 2050.

Transportation is responsible for about a third of Dallas’ greenhouse-gas emissions, most of which come from motor vehicles. More than three-quarters of Dallas workers commute alone, according to the city’s climate plan. About 11% carpool, 4% use public transportation and 2% walk. Less than half a percent cycle. Two percent are also “super commuters,” meaning their drive to work takes more than 90 minutes.

Dallas’ sprawl has been a major contributor to the problem. “Despite having the longest light rail system in the nation, unsustainable land development patterns continue to promote the use of private vehicles,” the city’s climate plan reads. “Solutions are aimed at shifting the dominant commuting mode away from single-occupancy, gasoline-powered vehicles. These actions have high potential to reduce overall emissions, reduce rush hour congestion, and improve air quality.”

Activists have criticized the plan for its lack of concrete deadlines and what they describe as vague goals. “Most are without imagination or timelines, meaning that even the most milquetoast-like recommendations being made will have to be fought for tooth and nail to be done in a timely manner,” Schermbeck wrote in a blog post

Hope Endrenyi, an organizer for the Dallas chapter of the Sunrise Movement, a youth-led climate advocacy group, said the plan has some positive elements — emphasizing the need for more affordable housing near public-transit hubs, for example, and more charging stations for electric vehicles. 

But she and other activists say it could go further by encouraging density in development through zoning. Increased density is one of the most important factors in making communities more walkable, boosting the use of public transportation and cutting transit times by car. 

A coalition of eleven local groups has created its own plan, called the Dallas People’s Climate Action Plan. It recommends building sidewalks and bike lanes throughout the city, discouraging the city from selling land to the Texas Department of Transportation for additional highway construction and creating a public utility that uses 100% renewable energy by 2030, among other things.

“Having a climate action plan is great, so kudos to the city for pursuing it,” Endrenyi said. But “it’s not ambitious enough, it’s not fast enough, and a lot of the things in the plan are not enforceable.” She and other activists are pushing for wider use of public transportation instead of focusing only on electric vehicles – city planners’ preferred solution. Even with government subsidies, Endrenyi said, the battery-powered vehicles are expensive and require the environmentally destructive mining of scarce minerals like lithium and cobalt.

Dallas Area Rapid Transit has seen flat or declining ridership over the past decade.
Credit: Adobe Stock

Dallas Area Rapid Transit (DART), a private company that operates buses, light rail, streetcars and a ride-hailing service in Dallas and 12 surrounding cities, has seen flat or declining ridership over the past decade. In 2012, the system recorded 66.3 million rides. In 2019, the last year before the COVID-19 pandemic, it logged 66.7 million. Ridership fell off substantially from 2020 through 2022 but has shown signs of improvement this year.

Schermbeck dismissed the idea that public transportation is a hard sell in North Texas. He points to the popularity of the electric Texas Interurban Railway system that operated from the 1910s to 1940s and carried riders from Sherman to Waco and Dallas to Fort Worth.

“We have a history of appreciating and using public transportation,” he said. “It’s because that’s been denigrated over time in favor of the car that we don’t have that kind of infrastructure anymore.”