The Italian glassblowers of Murano have survived plagues and pandemics. They transitioned to highly prized artistic creations to outrun low-priced competition from Asia. But surging energy prices are shattering their economic model.

The dozens of furnaces that remain on the lagoon island where Venetian rulers transferred glassblowing 700 years ago must burn around the clock, otherwise the costly crucible inside the ovens will break. But the price for the methane that powers the ovens has skyrocketed fivefold on the global market since Oct. 1, meaning the glass-blowers face certain losses on orders they are working to fill, at least for the foreseeable future.