These videos show something many hunters don't believe, but Grizzlies CAN and DO climb too when they have a reason.
https://www.youtube.com/watch?v=dPnp3fLOER8

https://www.youtube.com/watch?v=sJFUbjRcr_0

https://www.youtube.com/watch?v=xvm5xlPSko4

I think being in the same tree with any bear could keep my undivided attention, but if it were a grizzly, the "oh-krap-o-meter's" needle would be climbing higher and faster.