However, at this year’s crucial COP26 climate conference in Glasgow, one of the loudest voices sounding off against the trend was that of Thunberg herself.

At a carbon-offset panel session on Wednesday, Thunberg and other activists stormed out, with the Swedish teenager decrying “greenwashing.” She reiterated that criticism in a series of tweets targeting fossil-fuel firms and banks for “trying to scale up offsetting and give polluters a free pass to keep polluting.”

“Offsetting is often a dangerous climate lie,” she wrote. “Offsetting risks human rights transgressions and to harm already vulnerable communities. Offsetting is often hypocrisy and it is swirling around at #COP26.”

Specifically, Thunberg accused offsetting proponents of land-focused, nature-based offsetting—which usually involves planting trees—of allowing countries from the rich Global North to shift responsibility for their emissions onto the Global South, where people who weren’t responsible for the worst emissions are nonetheless suffering their effects.

The world’s most recognizable climate activist, who was filmed joining in a mildly profane protester sing-along on Monday, also cracked a joke that riffed on the offsetting concept, tweeting: “I am pleased to announce that I’ve decided to go net-zero on swear words and bad language. In the event that I should say something inappropriate I pledge to compensate that by saying something nice.”

Carbon offsetting is a crucial part of many companies’ plans to achieve a net-zero carbon impact, partly because it can be more convenient than actually reducing emissions. However, there remains little in the way of standardization or oversight.

The Taskforce on Scaling Voluntary Carbon Markets, an initiative led by former Bank of England governor Mark Carney, last week announced a governance board that aims to “bring greater quality and integrity to the voluntary carbon markets.” The board said it is reserving three seats for “representatives from Indigenous peoples and local communities,” addressing the issue raised by Thunberg and many others.

Thunberg clearly wasn’t impressed, tweeting Wednesday that “it is time to take down the Taskforce on Corporate Scams.”

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