It would need to be many, many orders of magnitude bigger. Chicxulub was approximately 10E6 more energetic than Tsar Bomba, and it didn't even manage to kill of

It would need to be many, many orders of magnitude bigger. Chicxulub was approximately 10E6 more energetic than Tsar Bomba, and it didn't even manage to kill off all life. And that barely left a dent in the surface of the planet. Also worth noting is that bigger bombs don't scale particularly well in terms of damage. Double a bomb's size, and much of it immediately just goes to outer space. Another large part of it is reflected from the surface of the planet to go, again, to outer space. Damage at radius r ~ E^(1/5).