It is an alert system mostly used for child abduction emergenencies: "An AMBER Alert or a Child Abduction Emergency (SAME code: CAE) is a child abduction alert system. Originating in the United States in 1996, there are now similar systems in a number of other countries." (source: en.wikipedia.org/wiki/AMBER_Alert)
Why not using the nofollow attribute[1]? It exists for this specific use-case.
[1] https://en.wikipedia.org/wiki/Nofollow