Ms Thunberg said: "It is not a secret that COP26 is a failure. It should be obvious that we cannot solve a crisis with the same methods that got us into it in the first place."
She said: "We need immediate drastic annual emission cuts unlike anything the world has ever seen.
"The people in power can continue to live in their bubble filled with their fantasies, like eternal growth on a finite planet and technological solutions that will suddenly appear seemingly out of nowhere and will erase all of these crises just like that.
"All this while the world is literally burning, on fire, and while the people living on the front lines are still bearing the brunt of the climate crisis."
She described the UN climate change summit as a "two-week long celebration of business as usual and blah, blah, blah" to "maintain business as usual" and "create loopholes to benefit themselves".
Ms Thunberg added: "We know that our emperors are naked."
