It "will set in stone Europe's position as a climate leader on the global stage and will inspire many of our partners." But 17-year-old Swedish eco-warrior Thunberg poured cold water on von der Leyen's enthusiasm and accused Europe of making false claims of leadership on the environment.
The European Union must stop "pretending that you can be a climate leader and still go on building and subsidising new fossil fuel infrastructure," the Swedish activist told a committee hearing at the European Parliament.
Thunberg was in the Belgian capital ahead of a Friday climate action protest, but had also been a guest of Von der Leyen at a meeting of top EU officials that approved the proposal.
The proposed climate text aims to enshrine into law the EU's grand ambition of zero net carbon emissions by mid-century. It would also give the EU executive new powers to impose emission targets on member state governments, a measure welcomed by greens and some activists. But handing more power to the commission, the EU's executive arm, faces almost certain opposition from the national governments and the European Parliament which must ratify the proposal.