A photo from the U.S. National Oceanic and Atmospheric Administration shows a coral reef off the Caribbean island of Bonaire. A policy paper to be published in the July 18 issue of the journal Science says saving endangered species like sea corals may have to include relocating them to new habitats. (NOAA/Associated Press)

Consider it the modern equivalent of Noah's Ark: scientists say policy-makers should consider moving species outside their historic ranges to prevent extinction caused by climate change.

A group of Australian and U.S. researchers suggests that if current conservation practices are not enough, more drastic measures may need to be taken.

"Resource managers and policy-makers must contemplate moving species to sites where they do not currently occur or have not been known to occur in recent history," wrote lead author Ove Hoegh-Goldberg, a professor at the University of Queensland's Centre for Marine Studies, in Friday's issue of the journal Science.

Hoegh-Goldberg and his colleagues recognize the proposal is controversial, and "flies in the face" of conventional conservation practices, given that man's history of migrating species into new habitats — intended or unintended — has often had disastrous results on the new environment. The introduction of the cane toad to Australia has had dire consequences for native wildlife, as an example.

But they argue better understanding of habitat requirements could allow low-risk assisted colonization.

"We are not recommending placing rhino herds in Arizona or polar bears in Antarctica. We are, however, advocating serious consideration of moving populations from areas where species are seriously threatened by climate change to other parts of the same broad biogeographic region," the scientists say.

Hoegh-Goldberg, whose work focuses on endangered coral reefs off the coast of Australia, gives the example of populations of staghorn corals, where some genetic strains of the species living at lower latitudes — that is, closer to the equator — have proved more adaptable to higher temperatures than those corals at higher latitudes.

Introducing these more adaptable corals to higher latitudes may hold little risk while preserving the reefs, since the species itself remains intact.

Beware 'law of unintended consequences,' critic says

University of Windsor professor Hugh MacIsaac, the director of the Canadian Aquatic Invasive Species Network, said replacing more thermally adapted strains of species would lead to little disruption, but that moving species to entirely new habitats poses a greater risk.

"These introductions must be done with caution because the law of unintended consequences often applies, and the new species may impact the recipient community in ways that were not anticipated," he wrote in an e-mail.

A good example, he says, is the Caspian kilka, a small fish that's become endangered in its native region in the Caspian Sea but has become an invasive species in the Volga River system in Russia.

He also suggests the cost and planning to initiate a long-term plan like the movement of a species may make any question of the consequences academic.

"This could be a bit of pie-in-the-sky thinking," he said. "Our funding cycles tend to be short, government attention is often short, but what the authors prescribe are (in some cases) long-term solutions."

John Weaver, a Montana-based conservation scientist with the Wildlife Conservation Society, said the paper addresses a subject environmentalists will have to face soon.

"I think raising the question of relocation, as troubling as it may be, is necessary to begin debate," said Weaver.

He said a good example of a species suitable for such relocation in North America would be the pica, an alpine rodent that has been forced to move to higher altitudes as temperatures rise in California. He said a similar subspecies of pica lives in the cooler mountains of British Columbia, making that a possible destination for such a relocation.

But uncertainty over climate change predictions makes such a move tricky. If temperatures warm in California at a quicker pace than they do in B.C., the pica might not find the northern climate suitable, he said.

"The question becomes, when do you make the rescue attempt," he said.

Tackling the thorny issue of assisted colonization opens up other difficult decisions environmental scientists will have to make as regional climates change, he said, including deciding which species to save if resources are limited.