Piketty: Tax the Rich to Fight Climate Change and Inequality

French economist Thomas Piketty has called for taxing the wealthiest individuals to simultaneously tackle climate change and social inequality, arguing that the green transition will fail if it is perceived as burdening workers while sparing the rich. In an interview broadcast on RTBF on June 26, 2026, the co-director of the World Inequality Lab outlined a vision for restructuring the global economy by 2100.

The Global Justice Report

Piketty’s proposals are grounded in the “Global Justice Report,” published on June 4, 2026, by the World Inequality Lab. Co-authored with Lucas Chancel and 45 international researchers, the report presents what its authors describe as a “scientific fiction” — a rigorously modeled utopian plan for global economic transformation. As RTBF reported, the plan envisions a world where average income converges to approximately €5,000 per month globally by 2100, and the bottom 50% of the population would hold roughly one-third of global wealth, up from just 2% today.

The report rests on three pillars: accelerated decarbonization of the global economy, with investments of 3-4% of global GDP per year; a shift toward “sufficiency” or sobriety, including reducing average working hours to around 1,000 per year by 2100; and drastic reduction of inequality through progressive taxation.

Taxing the Wealthiest

Central to Piketty’s argument is a system of progressive wealth taxation, including a global wealth tax of up to 20% for billionaires and top income tax rates reaching 90%. “90% was what Franklin Roosevelt used, and it corresponded to the period of maximum prosperity for the United States,” Piketty said in the interview, pointing to the period from 1930 to 1980 when the top marginal rate in the US remained at that level.

Piketty argued that historical data shows the US economy did not collapse under high taxation. “All the historical data we have shows that not only did American capitalism not collapse, but in fact it corresponded to the period of maximum prosperity for the United States in terms of productivity and growth,” he said. The revenues would be channeled into a global sovereign wealth fund, which would finance decarbonization, education, and healthcare worldwide.

The Belgian Context

The interview arrives amid a European heatwave and a heated political debate in Belgium over wealth taxation. On June 23, 2026, the centrist party Les Engagés, led by Yvan Verougstraete, proposed a tax on financial assets exceeding €500,000, aiming to raise €2 billion toward Belgium’s budget effort. The proposal was fiercely rejected by the liberal MR party, whose president Georges-Louis Bouchez called it “tax rage” and “economic madness.” As RTBF reported, the two parties are both coalition partners and electoral rivals, now neck-and-neck in opinion polls.

Piketty endorsed such wealth taxation measures. “From the moment we don’t want to burden the poorest and the middle classes, we must make the richest contribute,” he said.

Lessons from the Yellow Vests

Piketty cited the French “Gilets Jaunes” (Yellow Vests) movement as a cautionary tale. The French carbon tax, he argued, failed because it disproportionately burdened car-dependent workers while the revenue was used to abolish the wealth tax for the wealthiest 1%. “When you have this type of approach to the ecological question, inevitably, at some point people are not happy and feel like they’re being taken advantage of,” Piketty said. “The term ‘social class’ is terribly missing from the current climate debate, and that explains the unpopularity of many environmental policies.”

Philosophical Support

The report has drawn support from philosophers and commentators. Florent Guénard, writing in Philosophie magazine, described the report as a “realistic utopia” that demonstrates economic inequalities are “the product of our political decisions. They are not natural.”

What’s Next

Piketty acknowledged the political challenges of implementing such a global tax system, including the risk of capital flight. The report proposes starting with a coalition of willing countries and imposing tariffs on non-participants. “What makes me optimistic,” Piketty concluded, “is that there is a demand for climate justice, for economic justice, coming especially from the Global South, which is going to create a very strong movement. I think Europe will have to listen.”

As Belgium grapples with its budget crisis and a heatwave that has pushed temperatures above 40°C, the debate over wealth taxation and climate justice is likely to intensify in the weeks ahead.