The present invention relates to dynamic spectrum refarming with multiple carriers. At a first communication system of a first radio access technology, a request is received in a first signaling message from a second communication system of a second radio access technology, the request including information on availability of spectrum blocks shared between the first and second communication systems. The availability of the spectrum blocks may have been determined based on a load of the second communication system. The first communication system performs carrier aggregation mechanisms based on the information with respect to the spectrum blocks, and may transmit a response to the request in a second signaling message to the second communication system, the response including an acknowledgment of an activation/deactivation of at least one additional carrier and/or a corresponding carrier aggregation.