Washington: In a pointer to the gravity of the situation, scientists have called for a last-resort conservation measure like the relocation to safer habitats of species endangered by climate change.

Many species are today endangered because of climate change, but they are unable to respond as they would historically by moving to safer habitats because they are hemmed in by human settlements.

Hence relocation, or translocation, of species may be necessary to ensure colonisation of new geographic regions.

"When I first brought up this idea some 10 years ago in conservation meetings, most people were horrified," said Camille Parmesan of the University of Texas, an advocate of translocation.

"But now, as the reality of global warming sinks in, and species are becoming endangered, I'm seeing a new willingness in the conservation community to at least talk about the possibility of helping out species by moving them around."

Parmesan and her colleagues point out that assisted migration can never be a major solution for wildlife, but could be used to help a few species that biologists and the public deem to be important enough for the effort and could otherwise go extinct.

The species would need to be easy to collect, raise or move. Its habitat requirements would need to be well understood, and there would need to be viable habitat options outside the species' current range.

In a paper published in the latest edition of the journal Science, she and her colleagues present a conceptual framework that includes fundamental questions that must be addressed before translocation - such as risk of extinction if nothing is done, versus risk of harm to the new community if the species is moved there.

In addition to biological considerations, their framework includes social dimensions of the issue, such as cost and inherent value people place on the target species.

The authors argue that the most suitable scenario is when the risk of extinction of the target species is high in its historic range, but the risk to the community into which the species will be imported is low.

"Passively assisting coral reef migration may be acceptable, but transplanting polar bears to Antarctica, where they would likely drive native penguins to extinction, would not be acceptable," Parmesan said.

It might also be appropriate when the likelihood of successful colonisation is high, but the time and cost to perform transplantation is low.

"Conservation has never been an exact science, but preserving biodiversity in the face of climate change is likely to require a fundamental rethinking of what it means to 'preserve biodiversity'." IANS