Polar bears

Seal Study Reveals Why Polar Bears Are All so Emaciated Now

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In December 2017, video footage of an extremely emaciated polar bear went viral. Louder voices claimed the bear was a victim of climate change, while some experts questioned whether his tragic state was actually the result of illness. While we still don’t know what drove the dying bear to that state, the video’s release reignited a conversation about conservation: Polar bear populations have declined by 40 percent over the past decade, and we’re now at serious risk of losing them entirely.

The declining populations have largely been linked to changing sea ice conditions, but until now, scientists have been unable to identify exactly what mechanisms are causing stressful conditions and higher mortality rates in polar bears.

In a paper published Thursday in Science, a team led by University of Santa Cruz scientists offer a new theory: When it comes down to it, polar bears have high energy demands, and historically they have met those demands by eating fat-rich, calorie-dense seals. But with sea ice decreasing across the Arctic at a rate of 14 percent per decade, the number of seals available has dropped dramatically, and this has taken its toll on polar bears.

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Female polar bears without cubs were monitored as they hunted for prey.

In the study, the researchers observed female polar bears living near the Beaufort Sea during the spring in 2014, 2015, and 2016. Over periods of eight to 11 days, the scientists measured the bears’ behavior, hunting success, and metabolic rates, returning annually to repeat the process. Their analysis clarified a crucial characteristic about the bears: Their field metabolic rates — the measure of how quickly they spent their energy — were actually 50 percent higher than previous studies had predicted. Five of the nine bears lost a notable amount of body mass, suggesting that they weren’t meeting their energy demands with enough prey.

 Polar bears need a huge amount of energy to thrive. For these bears, simply walking expends more energy than it does for similarly sized mammals. They occupy expansive home ranges and swim for extended distances to hunt for marine prey, and the effect climate change has had on the Arctic sea ice has forced polar bears to search even further than usual for seals.
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An adult female polar bear wearing a GPS satellite video-camera collar used for this study.

“Because metabolism determines the rate at which organisms require energy from their environment, measures of polar bear metabolic rates provide an important metric for linking declines in Arctic sea ice to polar bear survival,” the researchers write.

“Changes in energy balance resulting from increased energy expenditure or reduction in foraging opportunities could lead to declines in body condition, survival, and reproductive success.”

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This is a polar bear still-hunting at a seal hole on the sea ice of the southern Beaufort Sea.

In short, the bears aren’t just suffering from a lack of food; they also need a lot more food to survive than we first thought. The effect of low seal populations was especially pronounced because bears typically catch most of the prey they need to stay alive throughout the year between April and July. This study was conducted in April, and by then more than half of the bears had lost the body mass crucial to their survival.

Arctic warming creates “an issue of how much fat they can put on before the ice starts to break up, and then how much energy are they having to expend,” said study co-author, University of Santa Cruz Ph.D. candidate, and United States Geological Survey wildlife biologist A.M. Pagano in a statement on Thursday.

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Manhattan Project-sized effort is needed to create artificial Arctic ice ‘to prevent climate catastrophe’

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Polar bears are struggling because they use sea ice to hunt seals and other prey

Wind turbines could be used to create more sea ice in the Arctic in a massive geoengineering scheme on the scale of the Manhattan Project, scientists have said.

The increasing loss of ice, which reflects much of the heat from the sun, and the release of currently frozen stores of potent greenhouse gas methane threaten to create runaway global warming that would affect the entire planet.

Experts believe the Arctic could be essentially free of sea ice for the first time in about 100,000 years within the next few decades. The famously impassable North West Passage is already open to shipping and fossil fuel companies are considering drilling in the region.

A team of scientists from Arizona State University has now suggested trying to counteract the loss of sea caused by rising temperatures in the Arctic, which has seen increases well above the global average. In Svalbard, winter temperatures have been up to 11C higher than the late 20th century.

They said this could be done by using wind power to pump water from below the existing sea ice to the surface, where it would freeze more readily.

It would, however, be a massive undertaking on the scale of the Manhattan Project, which saw the US develop the first nuclear bomb.

Climate scientist Dr Peter Gleick, president of the Pacific Institute in California, has warned that the rapid warming of the Arctic is “unprecedented” and could have a “catastrophic” effect on the climate of much of the world.

The jet stream, the usually steady flow of air circling the globe near the Arctic, has already changed, developing large loops which carry warm air towards the North Pole and freezing air south.

Arctic and Antarctic sea ice reaches record lows

The researchers estimated covering more than 10 per cent of the Arctic with the wind-powered pumps would cost about $500bn (£404bn) over 10 years.

However, writing in Earth’s Future, a journal of the American Geophysical Union, they said doing this “could more than reverse current trends of ice loss in the Arctic”.

They warned that even if humans stopped producing carbon dioxide emissions it would still be “too late to prevent loss of summer sea ice in the 2030s”.

 “Restoring Arctic sea ice thus probably requires a local solution tailored to that part of the climate system,” the scientists wrote.

“Happily, though, any prevention of Arctic sea ice loss has the advantage of arresting the most powerful feedback in the climate system and making global climate change easier to deal with.”

The pumps could also potentially be used to increase the amount of sea ice cover to beyond historic levels.

“Could this approach be used to help the Arctic cool the Earth more effectively than it did in the 1980s and before?” the researchers wondered.

Fresh snow reflects up to 90 per cent of sunlight, while sea ice reflects up to 70 per cent. Open water, however, absorbs about 94 per cent of the energy from the sun.

“[The] loss of sea ice represents one of the most severe positive feedbacks in the climate system, as sunlight that would otherwise be reflected by sea ice is absorbed by open ocean,” the researchers wrote.

“We propose that winter ice thickening by wind-powered pumps be considered and assessed as part of a multi-pronged strategy for restoring sea ice.

“Deployment over only 10 per cent of the Arctic… would require consumption of only about 13 per cent of the US steel production, and roughly five per cent of worldwide container ship capacity.

“These are expensive propositions, but within the means of governments to carry out on a scale comparable to the Manhattan Project.”

Other suggestions for geoengineering to reduce the effects of climate change include creating clouds by pumping seawater into the air, reflecting light from the sun in space, planting massive forests to absorb carbon dioxide and adding fertiliser to the sea in select areas to increase the numbers of organisms that absorb carbon dioxide.

Such projects have been criticised in the past for tinkering with the planet, but the researchers argued it was time to accept humans were already altering the climate artificially and needed to do something about it.

The researchers said: “The term ‘geoengineering’ is used pejoratively by those who feel it is morally irresponsible to try to alter the climate system in an attempt to prevent ecological disasters, mass extinctions, and human misery brought on by displacement, famine and war.

“It is argued that: our knowledge of the climate system is imperfect; that lessening the effects of climate change in one area (eg temperature increases) does not fix the problem in other areas (eg precipitation patterns, ocean acidification); that the only solution to all of these problems is a rapid reduction in carbon dioxide and other greenhouse gas emissions; that actively working to improve the climate presents a moral hazard, as producers of carbon dioxide emissions will feel less pressure to work toward a solution; and that assuming an active role in the climate commits us morally and practically to a permanent role in the climate.

“All of these arguments are valid, and perhaps stewardship of the Earth’s climate is not a responsibility to be desired; but again, the alternative is to continue altering the climate without any purpose or plan.

“We prefer the term ‘geodesign’ in recognition of the fact that the climate is a highly integrated system that may be impossible to ‘fix’ simply through application of a technology, yet which might be improved by viewing the climate as a planetary system, accepting the role of humans in the climate, and designing a new role for humans in the climate.”