June 1, 2006 — Despite the difficulties inherent in predicting climate changes over decades and centuries, Earth's longer term forecast is simple: Same as the last million years.
That means plenty of meteor impacts, supervolcanic eruptions, megaquakes and worse, says a geologist who is taking a novel look at Earth's last million years to forecast the next.
Although a million years is 100 times the age of human civilization, it's just a small hop on the geological timescale, says Steven Dutch of the University of Wisconsin, Green Bay.
Dutch used geological knowledge of the Earth to explore one thousand, ten thousand, one hundred thousand, and finally a million years into the future, reporting his results in the current issue of the journal Geosphere.
"A million years is a little while (geologically), but that’s ten ice ages in the future," said Dutch. "Events that are rare or unknown in recorded history become almost inevitable, even frequent, in the near geologic future."
Even without major catastrophes, gradual geological change will dramatically alter many landscapes. Some examples Dutch cited are Niagara Falls, San Francisco, Hawaii and New Orleans.
At Niagara Falls, the water drops over relatively hard dolomite cliffs, which are eroding at a rapid clip. Once worn away, the softer rock upstream will erode even faster until it encounters another layer of hard rock at Tonawanda, NY, and creates another set of falls there in about 14,000 years.
In California the temperamental San Andreas fault will set off about 7,000 earthquakes of magnitude eight in the next million years, offsetting the geography of San Francisco more than 15 miles. That will split the San Francisco Peninsula into a fork.
Over the same million years the Hawaiian Islands will have moved about 60 miles northwest, Dutch said. The deep undersea volcano called Loihi, to the southwest of the island of Hawaii, will have grown into a new island rivaling today’s Mauna Loa volcano.
On the Gulf Coast, the Mississippi River outlet will shift in location many times, leaving today's New Orleans far from the river, but still sinking.
Over a million years there will have been hundreds of meteor impacts causing regional effects and a good chance of a really big one with global effects, Dutch reported. It’s "virtually certain" there will be major supervolcanic eruptions in the next million years, he said.
Even the stars will show obvious signs of change in as few as 10,000 years, said Dutch. Our solar system will have moved 7.5 light years in its orbit around the center of the Milky Way, altering the shapes of familiar constellations.
"There is such a gulf between geologic time and human time," said seismologist George Keller of the University of Texas and a Geosphere editor.
It’s been a major hurdle in helping people understand what geologists do and what they are learning about the planet, Keller said, adding, "I think scientists in my field have been thinking about how to communicate that to the public."
Dutch’s work is a good way to make geologic time more real, Keller said.
