The day may soon come when some of the 19 polar bear populations in Canada, Alaska, Greenland, Norway, and Russia will have to be fed by humans in order to keep them alive during an extended ice-free season or prevent them from roaming into northern communities. Some bears may have to be placed in temporary holding compounds until it is cold enough for them to go back onto the sea ice. In worst-case scenarios, polar bears from southern regions may have to be relocated to more northerly climes that have sufficient sea ice cover.

It is time to begin making detailed plans to save the world’s 20,000 to 25,000 polar bears.

Far-fetched, draconian, and unlikely as some of these scenarios may sound, 12 scientists from Arctic countries are, for the first time, suggesting that the five nations with polar bear populations need to start considering these and other management strategies now that sea ice retreat is posing serious challenges to the bears’ survival. In worst-case scenarios, the scientists say that polar bears with little chance of being rehabilitated or relocated may have to euthanized. Zoos, which are currently having a difficult time acquiring polar bears because of stringent regulations that prevent them from doing so, will at some point likely be offered as many animals as they can handle, according to the scientists.

This crisis management plan for polar bears as Arctic sea ice disappears is laid out this week in an article in Conservation Letters, the journal of the Society for Conservation Biology. Polar bear experts Andrew Derocher, Steve Amstrup, Ian Stirling, and nine others say that with Arctic sea ice disappearing far faster than originally estimated, it’s time for Arctic nations to begin making detailed plans to save as many of the world’s 20,000 to 25,000 polar bears as possible.

“We really never have been here before,” says Amstrup, chief scientist for Polar Bears International and a lead author of a landmark U.S. government-appointed panel that predicted in 2008 that two-thirds of the polar bears in the world could disappear by mid-century.

The University of Alberta’s Derocher added, “We have covered the science side of the issue very well, but the policy and management aspects are locked in the past. We still manage polar bears in Canada like nothing has changed. Other countries are moving on some aspects of future polar bear management, but it is glacial compared to the actual changes we’re seeing in sea ice and the bears themselves.”

The alien-sounding concepts presented in this week’s paper — with names like supplemental feeding, diversionary feeding, translocation, and intentional population reduction — may become increasingly put into practics as Arctic sea ice, continues to disappear in spring, summer, and fall. Forty years ago, when the first International Polar Bear Agreement was ratified, the threats facing polar bears were chiefly hunting and mining and oil development. But the overriding threat now is climate change.

Thousands of seals would have to be killed every summer to meet the needs of hungry bears.

Without adequate sea ice for enough of the year, many bears will not be able to use the ice as a feeding platform to hunt their favored prey, ringed seals. As a consequence, polar bears will be forced to spend more time fasting on land, where they pose a greater risk to human populations in the Arctic. The International Union for the Conservation of Nature’s Polar Bear Specialist Group recently concluded that only one of the 19 polar bear subpopulations is currently increasing. Three are stable and eight are declining. For the remaining seven subpopulations, there is insufficient data to provide an assessment of current trends.

Derocher and some of his colleagues have been thinking about the need for dramatic rescue plans for polar bears for at least five years. The scientists say a record disappearance of Arctic summer sea ice in 2007 increased the urgency for emergency planning, as did research by Peter Molnar — Derocher’s one-time graduate student and now a post-doctoral fellow at Princeton University — suggesting that the collapse of some polar bear populations may occur sooner than climate models predict.

Over the past two years, scientists began considering a specific list of actions to save polar bear populations. A draft paper by Derocher and others was circulated last August just as Arctic summer sea ice hit striking new lows, with sea ice volume dropping 72 percent from the 1979-2010 mean, and ice extent falling by 45 percent from the 1979-2000 mean.

“If you talk to any of the polar bear biologists, you’ll find that the public is already asking us about the issues we cover in the paper,” Derocher said in an interview. “I’ve had well-positioned conservationists waiting to start the fund-raising to feed polar bears.

“I don’t view the options we lay out as a way of not dealing with greenhouse gases,” he added, “because without action on that front, there’s little that could be done in the longer term to save the species, and we’ll see massive range contractions and possibly extinction.”

Two key ideas in the current paper are supplemental feeding, to make up for the loss of ringed seals that polar bears can kill on ice, and diversionary feeding to draw hungry polar bears on shore away from human settlements. Supplemental feeding is nothing new; it is done for numerous species, from elk in the United States to brown bears in Eastern Europe. But feeding polar bears poses major challenges.

Cubs could be flown to more northerly regions and placed with females that would rear them as “foster” cubs.

Derocher said in an email that the goal would be to distribute food, such as seals, in sufficient quantities over large distances so that hungry bears, forced ashore by lack of ice, would not come into conflict by vying for the same food. The goal would be to keep bear populations widely scattered, as attracting too many bears to central locations could increase the risk of disease transmission. Helicopters could be used to deliver the seals, but the logistics and expense of such a plan would be daunting. Thousands of seals would have to be killed by wildlife officials every summer to meet the needs of hungry bears, who each consume up to five seals a week.

“There is not a lot of experience with any of these issues, so it would take coordination and learning from the east Europeans, who already feed brown bears,” said Derocher. Still, he is convinced that we will someday be feeding polar bears in the wild. “The public pressure will be intense to do so,” he says, “and the public influences policy.”

Another possible measure would be to relocate bears from more southerly regions, such as Hudson Bay, to more northerly regions, such as M’Clintock Channel in Nunavut in the high Canadian Arctic. The number of bears in the icier M’Clintock Channel area has been significantly reduced by overhunting, so there is room to relocate bears from Hudson Bay and James Bay without creating territorial conflicts, scientists say. Cubs from one population could also be flown to more northerly regions and placed with females that would rear them as “foster” cubs, Derocher said.

In Derocher’s view, feeding and relocation will only work for polar bears so long as they have some habitat remaining, which is unlikely in the next century if greenhouse gas emissions are not curbed dramatically. “Keeping hundreds of semi-wild bears on a diet of bear chow doesn’t fit my personal philosophy, but perhaps centuries from now, it will be viewed as visionary, if we eventually control those greenhouse gases,” Derocher says.

The paper notes that another option is holding polar bears temporarily in the Arctic in enclosures during low sea ice periods. A similar thing is now done with problem bears around Churchill, Manitoba on western Hudson Bay.

The report acknowledges that in a worst-case scenario, where the primary goal is to preserve the genetic structure of the species, zoos around the world could play an important role. Amstrup, the U.S. zoologist, says there are signs that the U.S. is at least considering the idea of easing restrictions on the importation of orphan cubs found in the wild.

“Regardless of whether reintroducing polar bears or their genes ever is practical, we cannot overlook other ways zoos may contribute,” he says. “Dozens of species are healthier and more abundant in the wild today because of captive breeding and other zoo programs.”

As a last resort, the paper mentions “intentional population reduction’” — the killing of starving bears. “Controlled reduction of population size through harvest might be necessary to ensure both human safety and a viable but smaller polar bear population as a result of declining habitat,” the paper said. “Euthanasia may be the most humane option for individual bears in very poor condition that are unlikely to survive. Under these circumstances, it will be important to develop clear guidelines for identification of starving animals.”

Amstrup emphasizes that the purpose of the article is not to promote one management strategy over another or to suggest that they will all work. “The purpose is to remind the readers, and hopefully policy people, that the long-term future of polar bears is in jeopardy,” he says. “It makes managers and policy people aware of the various kinds of on-the-ground actions that may be applied and makes them begin to think of the varying levels of cost that may be involved in the different options they may choose.”

Stirling, a biologist at the University of Alberta, said in an e-mail that the paper is “a starting point that clarifies the need to be developing some preliminary plans for dealing with such problems.” The scientists realize that it will be difficult to sell these controversial management strategies to the public and to policy makers. One impetus for action will likely be an increasing threat to humans in the Arctic from hungry bears being forced off the ice and onto land. “The sooner we consider the options, the sooner we’ll have a plan,” said Derocher. “The worst-case scenario is a catastrophically early sea ice break-up with hundreds of starving bears, followed by inappropriate management actions.

“It has always seemed that we’ve been behind the curve on climate change and polar bears,” he said, noting that conservation planning for polar bears has typically extended several decades into the future. “That time frame leads one to think you’ve got time. But the science is clear that this is a fallacy.”