No wonder the super-rich don’t tend to stop and smell the roses: The sky is blanketed in smog.

Private jet usage has skyrocketed 20% since the start of the pandemic, and the resulting emissions have jumped over 23%, according to a new report from the left-leaning Institute for Policy Studies (IPS) and the Patriotic Millionaires, who regularly urge the government to raises taxes on them. Often on board: the dynastically wealthy, who benefit from money passed down from one generation to the next, usually through a trust. Think major Succession vibes.

Over a quarter—26%—of the world’s “extremely wealthy” private jet owners either completely or partly inherited their wealth, according to the report, which looked at Wealth-X data regarding the relative net worths of jet owners and Federal Aviation Administration user data, as well as public information. With a wink, Kalena Thomhave, one of the report’s authors, coined a term for the scourge of trust funders in the skies: “heir pollution.”

Many family dynasties rely on private jets for much of their travel; the report references the Mellon family, whose original wealth stems from the founding of Mellon Bank in 1869, as an example.

But flying private is well-known to be just about the worst thing you can do from an environmental standpoint. Private jets emit at least 10 times more pollutants than commercial planes per passenger, per the report, and an estimated 1% of people are responsible for about half of all aviation carbon emissions.

That doesn’t seem to matter to the very wealthiest people. “The ultrarich consider their time to be at a premium […] and the consequential emissions, which are vast, don’t necessarily affect them,” Thomhave and fellow IPS report author Omar Ocampo tell Fortune.

But the reality is that, most often, flying private is just one of the manifold ways ultrarich people pollute the planet. Per a 2022 Oxfam study, the richest of the rich emit, on average, over 1 million times the carbon dioxide each year as 90% of the population. They also tend to invest in companies that produce more emissions, Oxfam found. Every year, the scale of emissions stemming from billionaires’ investments equaled the entirety of carbon emissions from France.

Trust fund babies benefit from lower tax burdens when flying

That private jets come a dime a dozen among the dynastically wealthy “illustrates the unfairness of our current system: Family wealth dynasties form when the rich devote their resources to protecting their wealth and inheritances from taxation,” say Thomhave and Ocampo. “This has resulted in fewer tax obligations for the ultrawealthy, but it results in a heavier tax burden for the rest of us.”

Thanks to many jet owners’ attacks on progressive taxation, a provision was passed in the 2017 tax reform that allowed them to immediately write off the entire cost of a private jet, the researchers said. While that specific provision is set to expire in 2027, it’s “merely a further example of the environmental and economic costs of inequality.”

The report argues for a 10% sales tax on all pre-owned private jets and a 5% tax on new ones, which would have generated $2.2 billion in revenue in 2022. It also advocates for several other reforms, such as levying a tax on private jet fuel and a tax on “ridiculously short flights.”

Even millionaires who come from generational wealth are on board. Abigail Disney, nephew of Walt and a member of the Patriotic Millionaires, once called private jets a “cancer” and says she sometimes flies business class.

Disney, a philanthropist who has long eschewed the vast trappings of her inherited fortune, said she understood that some very wealthy people fly private due to privacy and safety concerns. But she said they could fly business class on commercial flights just as well: “I fail to see what is so hard about that.”

This is hardly a new position of hers. In a 2019 interview, Disney said she’s donated approximately $70 million of her personal wealth since turning 21, and that she would support a law banning private jets, “because they enable you to get around a certain reality.”

While flying economy is significantly better for the earth than even flying first class—the latter generates seven times the emissions of the former—that’s not enough for Disney. This year, she tweeted in January, she’ll cut back on all air travel. “I’m weighing every trip against my personal cost/social benefit measure, from here on out.”

It’s unlikely that Disney’s peers will follow suit anytime soon. Per the IPS report, the private jet sector is smashing industry records: The size of the global fleet has grown 133% since 2000.