In Glacier National Park the melting glaciers that will, within a few decades, rob the park of its namesake feature, are a pretty easily predictable consequence of global warming. But I don’t think many of us thought the same thing could happen to Yellowstone’s geysers.

Old Faithful may not be so faithful anymore.

A long-term study of Yellowstone National Park’s iconic geysers suggests that dry spells caused by climate change are slowing—and may even stop—the geysers’ clockwork-regular eruptions.

Between 1998 and 2006, researchers monitored the schedule of five of the park’s geysers using temperature sensors.

The two best known geysers showed the most changes: The time between Old Faithful’s eruptions shifted from an hour 15 minutes to an hour 31 minutes, while Daisy Geyser’s interval shifted from an hour 40 minutes to two hours 50 minutes.

It would be a sad day if Old Faithful stopped erupting.