June 25 (Bloomberg) -- Plants found only in California may need to migrate about a mile (1.6 kilometers) a year into cooler or wetter regions to survive as global warming makes traditional habitats less hospitable, a scientific study found.

As temperatures rise and rain patterns change, many native species will need their seeds blown or carried by animals to the north or toward the coast, according to the investigation by researchers at three U.S. universities, whose results will be published tomorrow in PLoS-ONE, an online scientific journal.

Moving a mile a year would be a faster pace than achieved by flora that survived the changing temperatures during ice age thousands of years ago, said David Ackerly, a professor of integrative biology at University of California, Berkeley.

``I'm sure we will see some extinctions in the next 100 years,'' Ackerly, a co-author of the study, said in an interview. The study is the first to examine how climate change will affect an entire region of vegetation, its authors said.

The United Nations Intergovernmental Panel on Climate Change said last year the Earth will likely warm by 1.1 degree to 6.4 degrees Centigrade (2 degrees to 11.5 degrees Fahrenheit) by 2100, worsening droughts, melting ice caps and raising sea levels, unless greenhouse-gas emissions are slashed.

Introducing trees or flowers to areas where climate models project the Californian species may later thrive is being considered by biologists and botanists, though there are concerns about disease and other drawbacks to transplants, he said.

Native Oaks

California, almost 80 percent the size of France, is home to about 5,500 native plants, including roughly 2,400 that live only in the state. As temperatures warm, redwoods along California's coast may move farther north toward Oregon and native oak trees may no longer be found in the central part of the state, the study said.

A 10-degree Fahrenheit rise in average global temperatures during the next century may cause two-thirds of native species in the state to have their geographical range reduced by more than 80 percent, the scientists said.

Invasive species and fires also are going to increasingly threaten plants as weather warms and rain patterns change, said Harold Mooney, a professor of biological sciences at Stanford University in Palo Alto, California. Population increases in the state make it hard for plants to adjust too, he said.

Ice Age Comparison

``Climate change is happening and is going to have a big effect,'' Mooney said. ``But the population of the state is slated to increase substantially, and that means a lot of changes that will impact biodiversity.''

The study's findings don't reliably predict the fate of individual species, though they highlight the overall challenge plants face if temperatures continue to warm, Ackerly said.

``The magnitude and speed of climate change today is greater than during past glacial periods, and plants are in danger of getting killed off before they can adjust their distributions to keep pace,'' Ackerly said in a statement.

Researchers from the University of California, Duke University and Texas Tech University spent four years examining more than 2,200 native California plants, using models to project how the species would move during particular changes in temperature and precipitation. Earlier research has focused on how specific plants will be affected by climate change.

To contact the reporter on this story: Adam Satariano in San Francisco at asatariano1@bloomberg.net

Last Updated: June 25, 2008 05:10 EDT