Roundup #83: I told you so!

Howdy, folks! Today’s roundup is mostly a bunch of follow-ups to posts I wrote before. It’s very hard to decide when to post about a particular topic, and it often happens that some relevant news story or piece of data comes out a little bit later. These roundups are a good way of cleaning up those loose ends.

Today we start with a truly wacky policy proposal by the esteemed Thomas Piketty…

1. What on Earth is Thomas Piketty talking about?

Unlike many people, I never pretended to have read Thomas Piketty’s book, Capital in the Twenty-First Century. I simply didn’t read it. I did read a number of the papers that the book was based on, which is often a better and quicker way of getting the key points of a book like that. I thought those papers were a good and important addition to the economics literature, even if the messy reality of inequality didn’t always fit the simple story Piketty told, and the data he relied on was less reliable than we might want.

Despite the limitations of Piketty’s work, it sparked a long-overdue and generally healthy debate about inequality. And Piketty’s basic policy solution — tax rich people more — was pretty reasonable, even if his proposed numbers were too extreme. I did roll my eyes when Piketty stood on a stage at an academic convention and accused Greg Mankiw of being in the pocket of rich people.¹ But overall his work seemed pretty serious and often reasonable.

However, after years of relative silence, Piketty has burst back onto the scene with some work that seems very unreasonable. He and his team at the World Inequality Lab — which includes his longtime co-authors Emmanuel Saez and Gabriel Zucman — have come out with a grand plan for fixing the world. And for the most part, it’s total nonsense.

Piketty described the new plan in a thread on X. Its main focus, perhaps surprisingly, is not inequality — it’s climate change!

Thomas Piketty @PikettyWIL The key finding of the report is that energy transition alone will not suffice. We need to combine it with "sufficiency" to stay within 2 degrees. This includes labour hour reductions, growth caps in rich countries, less material consumption, and changes in food habits. 5:56 AM · Jun 4, 2026 · 499K Views 151 Replies · 58 Reposts · 250 Likes

First of all, Piketty’s baseline climate change scenarios appear based on a very outdated model — the RCP8.5 scenario, an extreme projection that essentially all serious climate scientists have now rejected. This choice of baseline suggests that Piketty et al. were trying to find ways to justify maximal policy intervention, instead of starting from the science.

Piketty’s preferred solution to climate change is degrowth. He envisions detailed central planning to achieve deliberate impoverishment of large portions of the world’s population — mandated reductions in the consumption of various specific goods, including food.

In addition to the dubious morality of deliberately impoverishing untold millions of human beings based on scientific models that have already been rejected, this kind of scheme is just utterly unworkable. Back in 2021, when I wrote about why degrowth is a political nonstarter, I declared that “implementing the kind of reallocation schemes that degrowthers throw around with abandon would require global economic planning that would put Gosplan to shame.” Piketty knows this, and thinks it’s a good thing.

Even more ridiculously, Piketty envisions a global fiscal authority to carry out this insane plan via global taxation: