Photo: Yellowstone Geysers May Stop Erupting, Study Suggests

Matt Kaplan
for National Geographic News

July 9, 2008

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.
His team found that over their study period, geyser intervals got longer as the park went into a prolonged dry spell.
The two trends appear to be linked, but only over considerable periods of time.
"As the region went into a drier climate, all intervals got longer," Hurwitz said.
Surprisingly, on a monthly basis not all analyzed geysers responded similarly to precipitation patterns in the park, yet over years the geysers underwent the same trends, he added.
The scientists say that if climate change continues to dry the area out, the intervals between geyser eruptions could get longer and longer. Under extreme conditions, the displays could even cease completely.
Hot and Bothered
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.
"Geysers are different from steam vents, mud pots, and hot springs—they have eruptions," said study leader Shaul Hurwitz at the U.S. Geological Survey in Menlo Park, California.
"We wanted to know if we could learn something about Yellowstone's hydrothermal system by analyzing the intervals between these eruptions."
While much remains unknown about how geysers respond to small changes in the environment, clear long-term trends are emerging, the researchers say.
The study appeared in the June issue of the journal Geology.
Steamy Situation
Yellowstone's most famous geysers, especially Old Faithful, are known for the regularity of their eruptions—it's a pattern solid enough for tourists to make plans around.
But geysers depend upon a unique combination of water supply, heat, and rock fractures, Hurwitz pointed out.
Even small earthquakes, slight variations in underground temperature, and tiny alterations in water availability can dramatically change the size and appearance of an eruption, and no one is exactly sure how. So Yellowstone's geysers are very susceptible to environmental changes like the increasing dry periods affecting Wyoming, Montana, and Idaho, Hurwitz said.
Michael Manga, a geologist at the University of California, Berkeley, said the new study may help solve the longstanding puzzle of how earthquakes affect geysers.
"This study shows that changing the ability of water to recharge the geyser affects eruptions," said Manga, who was not involved in the research. "Perhaps this too is how distant earthquakes affect eruptions—by changing the ability of surrounding water to recharge the geyser."
Ken Verosub, a geophysicist at the University of California, Davis, also was not involved with the study.
"While the effects of short-term climate fluctuations do not appear to be too significant, longer-term climate change looks like it can have a big effect on geysers," he said. "This could be bad news for tourism."