The teenage Swedish climate activist is in London to take part in protests demanding the financial system stops funding fossil fuel projects. She told the BBC's Andrew Marr that "change is possible" at the summit, if pressure on politicians is maintained.
Elsewhere in her interview, Ms Thunberg said poorer countries most affected by climate change should have a bigger presence at COP26. She added it was "not fair" that some nations would send "lots and lots" of delegates, while nations from the so-called Global South would be "under-represented".