But yes, I would say it is somewhere within similar order of magnitude
I am glad. It is important to understand this fact. I haven't seen it mentioned yet, anywhere.
People should update, not follow Carl Sagan blindly. He had "good intentions" when (probably) misinformed the world.
Important for what exactly? Why is it more important than 'total yield << sunlight in a day' fact? edit: Because forest fires and nukes are both nasty?
Just a reminder that some of the old threats are still around (and hence that AI is not only something that can go hideously badly, but also some thing that could help us with the other existential risks as well):
http://blog.practicalethics.ox.ac.uk/2012/03/old-threats-never-die-they-fade-away-from-our-minds-nuclear-winter/
EDIT: as should have been made clear in that post (but wasn't!), the existential risks doesn't come from the full fledged nuclear winter directly, but from the collapse of human society and fragmentation of the species into small, vulnerable subgroups, with no guarantee that they'd survive or ever climb back to a technological society.