This paper presents a multicast routing mechanism supporting the classical IP multicast service model that can dynamically use redundant forwarding in the parts of the network affected by a high rate of topology changes, while converging to regular multicast distribution trees where or when the network becomes relatively stable. The rationale is that intermittent connectivity directly affects the ability of routers to synchronize on their view of the network, thus making it difficult to converge on efficient distribution trees, while network wide broadcast may be prohibitively expensive for relatively sparse groups. We describe a hybrid approach, called Elastic Multicast, which dynamically expands to limited scope broadcast when needed, and converges single path forwarding if the network is stable, through independent routing decisions made at each node.