The Changbai (or Baitoushan, Paektu) volcano on the China/North Korea border is best known for its climactic caldera-forming eruption of 100km3 of comendite materials 1000years (1ka) ago. The polygenetic Changbai volcano also erupted moderate-volume pre-caldera comendite lava at ~4ka and small-volume post-caldera trachyte ignimbrite at ~0.3ka. Here we report 238U–230Th disequilibrium ages of zircons from lavas and ignimbrites of the pre-caldera (~4ka), syn-caldera (1ka), and post-caldera (~0.3ka) events. The zircon isochron ages are 12.2±1.1ka (2σ) for the 4-ka comendite lava and 12.2±1.7ka for the 1-ka comendite ignimbrite. Zircons from the 0.3-ka trachyte ignimbrite exhibit 3 respective peaks at 2.6±1.8ka, 130±10ka and >230ka. The indistinguishable zircon ages for the 4-ka pre-caldera eruption of comendite lava and the 1-ka caldera-forming eruption of comendite pumice and ignimbrite suggest that the 4-ka lava provides an early sampling of a much larger magma body at depth and thus serves as a kind of petrologic early-warning signal. In addition, the 4-ka lava may represent the lowest-temperature magma in the roof zone of a thermally zoned magma chamber that usually escapes first. The distinctive multi-modal zircon age distributions of the 0.3-ka trachytic eruption, however, reveal that this post-caldera eruption tapped a different magma body and indicate that Changbai's magmatic plumbing system had changed after the 1-ka caldera-forming climactic eruption. Our results suggest very short zircon and magma residence times for the Changbai volcano (8kyr for the 4-ka eruption, 11–12kyr for the 1-ka eruption and 2.3kyr for the 0.3-ka eruption). Display omitted •Pre-caldera 4-ka eruption and syn-caldera 1-ka eruption have zircon ages of 12ka.•4-ka lava provides an early sampling of a larger magma body and an early-warning.•Zircon ages from post-caldera 0.3-ka eruption are different from earlier eruptions.•Magma plumbing system changed after the 1-ka caldera-forming explosive eruption.•Magma residence times are short (2–11thousandyears) for all 3 eruptions.