Internet-based communication technologies can reduce both carbon emissions and financial costs of academic conferences for individual participants—especially those from non-rich countries. We consider currently available technological solutions and logistic formats. In July 2018, we organized the leading international conference on music cognition (ICMPC15/ESCOM10) as a multiple-location, semi-virtual event with hubs on four continents (Europe, North America, South America, Australia) and 600 active participants. Every talk was live-streamed to YouTube (unlisted with URLs accessible only to registered participants) and seen by two audiences (local, remote). Remote presentations were either real-time or delayed. Discussions were two-way audiovisual (Zoom). Student assistants managed the technology. The 24-hour program ran for five days, with normal working hours at each hub. Most (61%) participants approved of the semi-virtual format. Greenhouse-gas emissions per participant were reduced by 60–70% relative to an equivalent single-location conference. No talk was delayed or canceled for technical reasons. A semi-virtual, multiple-location approach improves the globality, cultural diversity, and accessibility of academic conferences. That in turn improves the relevance and long-term quality of academic content. In future, emissions and international time-difference problems can be further reduced by increasing the number of hubs. Every academic conference, regardless of size, discipline, or country, can benefit from live-streaming some or all presentations. Conference participants and organizers can contribute to global mitigation efforts while at the same time promoting their academic disciplines by taking advantage of modern internet communication technologies. Video recordings of talks contribute to documentation and dissemination.