Earlier this month, the World Inequality Lab, founded by Thomas Piketty, among others, released its annual data on inequalities of wealth, income, gender, and ecology. As usual, the report is expansive and worth reading in full. A particular highlight, however, comes in the section on global carbon inequality, which extensively details the disproportionate share of carbon emissions produced by the superrich. While people in wealthy countries do tend to emit more as a group, the very richest people worldwide are truly in a category of their own: taken as a whole, in fact, those in the global top 1 percent of income account for some 15 percent of emissions — more than double the share of those in the bottom half.

The reasons for this are straightforward enough. The lifestyles of the ultra-wealthy, almost by definition, involve consumption habits and patterns of behavior that carry a much bigger carbon footprint. As the Financial Times’ Stefan Wagstyl succinctly put it this summer: “Almost everything the wealthy do involves higher emissions, from living in bigger houses to running larger cars and flying more often, especially by private jet. Eating meat comes into it, as does owning a swimming pool. Not to mention a holiday home. Or homes.”

It’s hard to imagine a starker illustration of carbon inequality than the recent phenomenon of recreational space flights, like those undertaken by Jeff Bezos’s Blue Origin, Richard Branson’s Virgin Galactic, or Elon Musk’s SpaceX earlier this year — flights whose ambition was clearly to mainstream the whole idea of commercial space travel so that it can eventually become a more common (and perhaps profitable) enterprise.

So, just how much carbon do such flights emit?

Dig into this year’s World Inequality Report and you’ll find the astonishing estimate that a single, eleven-minute space flight emits at least seventy-five metric tons of carbon per passenger (according to researchers, this is actually an extremely conservative estimate, and the figure may well be in the range of two hundred fifty to a thousand metric tons per passenger). For comparison, the report’s data shows that as many as 1 billion people emit less than a single metric ton per year — meaning that a single passenger on a short space flight produces more carbon pollution in a few minutes than people belonging to roughly one-eighth of the global population will throughout their entire lifetimes.

Were commercial space travel to successfully expand beyond brief, suborbital flights, to lengthier trips or even prolonged orbital stays, it’s both easy — and terrifying — to imagine how much more significant the carbon footprint would quickly become. As it stands, at least one company is currently boasting of its plans to build and launch a luxury space hotel before the decade’s end. If those plans succeed as currently written on paper, the so-named Voyager Station will house nearly three hundred guests and more than a hundred crew members, putting the pollution produced by private space travel on an entirely new scale.

It’s as yet unclear, of course, whether commercial space flight can actually represent a viable or profitable business model in the decades ahead. What is clear is that the ever-rising consumption habits of the extremely wealthy are already placing an unsustainable burden on the global climate — and that private space travel undertaken on a larger scale could effectively represent a death sentence for the planet.