This answer is merely a supplement to the two very good answers extant when I started to write.
First, let me assume that your question is based on the subset of risks that increase work; that you're trying to estimate the additional work/rework that would be the consequence.
I think the "standard" answer is to add management ...
Trying to hand-off piecemeal tasks across time zones is not a good idea
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What you have is not a tool limitation!
If you have multiple teams in multiple time zones, try to keep whole projects at each location with fully self-contained teams (it is possible some of the team members may be remote). This is important because teams ...