(The Hill) – The wealthiest tenth of U.S. households are the source of 40 percent of national greenhouse gas emissions, according to research published in the journal PLOS Climate. 

Researchers, led by Jared Starr of the University of Massachusetts, Amherst, analyzed three decades of household income data from 1990 to 2019.

They found that during this period, the bottom 90 percent of households’ share of emissions has fallen, while the top 10 percent’s share has increased. The wealthiest 1 percent of households were responsible for between 15 percent and 17 percent of emissions. 

Starr and colleagues analyzed emissions associated with businesses owned by the households they analyzed, but also factored in revenues relating to their investments. For the top 10 percent, investment income makes up a large share of those households’ emissions — between 38 percent and 42 percent in the case of the wealthiest 10 percent. 

“The investment piece makes up an increasing share of the emissions responsibility as we look further up the income ladder,” Starr told The Hill in an interview. 

Just over 43,000 of the wealthiest 0.1 percent of households — 34 percent — were what the researchers dubbed “super emitters,” or those responsible for more than 3,000 tons of carbon dioxide-equivalent emissions per year. They also found wide racial disparities in responsibility for emissions, with non-Hispanic white households comprising the highest income-linked emissions and Black households comprising the lowest.

Emissions also varied by age cohort, peaking between the ages of 45 and 64 and then declining. 

The results indicate that policymakers may have been looking at potential carbon taxes and their structure from the wrong angle. “While consumer-facing carbon taxes have struggled to move from proposal to law in the U.S., an investment-based carbon tax may be more equitable, politically palatable, and equally justifiable,” they wrote, while acknowledging that this would likely face pushback from the disproportionate amount of the wealthiest Americans in politics.

“By thinking of carbon as an outcome of income generation rather than just an outcome of consumption, such alternative policy solutions become possible,” they wrote. 

Simply measuring according to consumption gives a misleading picture of who is responsible for the bulk of emissions, Starr said, and any tax on carbon that is consumption based would reflect that.

“Consumer-facing carbon taxes would hit poor Americans hardest because the emissions intensity of their purchases tends to be higher than higher-income groups because they’re buying things related to necessities,” whereas upper-income groups tend to be based around services, he said. 

“These low-income groups basically spend all that comes in, whereas as you move up the income ladder, the higher-income groups have really high savings rates, [and] money that they save or re-invest are not reflected in consumer-facing carbon taxes,” he added.