Polar Bears Face Higher Risk of Starvation Due to Climate Change

A new study suggests that polar bears may have much higher food needs than previously thought, spelling an uncertain future for these already at-risk animals.

The study, published this month in “Science,” examines the metabolic balance of polar bears. This term refers to the amount of energy the animals must exert to catch food, as well as the energy they require from their food.

The University of California Santa Cruz research team captured nine female polar bears from the Beaufort Sea region and used blood and urine samples to assess metabolic rates. That number gives scientists an estimate the bears’ energy use, which can then be used as a baseline for other insights.

From this data, the researchers determined that the bears would need to capture one adult ringed seal — their primary food source — or three juvenile ringed seals every 10 days to meet their energy requirements.

The scientists also fitted the bears with special GPS-enabled camera collars to track and record the bears’ activity.

Hungry polar bears

The researchers noted that the bears’ metabolic rates were higher than expected — 50 percent higher than other studies had predicted. That means that the animals need to consume more food than had previously been thought.

Given what we already know about the polar bear population’s declining numbers – 40 percent in the Beaufort Sea region — it’s no surprise that many of the bears in this study struggled to meet their food requirements.

Five of the nine bears in the study didn’t get enough food during the study period, and this resulted in weight loss – as much as 20kg across just 10 days. The researchers were quick to point out that in so-called “feast” months, it’s not uncommon for polar bears to catch more prey, as this is the season when juvenile seals are most easily accessible. However, as those seals grow older, and as the sea ice retreats, it becomes more difficult to prey on the seals. During some months, bears lose weight as they struggle to find food, and that’s to be expected.

What’s alarming about these findings, though, is how much the polar bears struggled to meet their basic food requirements — even in the months of April, May and June. These months are usually associated with good hunting, but according to this study, clearly even these so-called plentiful months don’t produce the “feast” that these bears need.

Melting sea ice puts more pressure on polar bears

Doctoral candidate Anthony Pagano of UC Santa Cruz explained:

We’ve been documenting declines in polar bear survival rates, body condition, and population numbers over the past decade. This study identifies the mechanisms that are driving those declines by looking at the actual energy needs of polar bears and how often they’re able to catch seals.

One of the big factors? Climate change.

The evidence for Arctic sea ice decline is overwhelming, and while the actual rate depends on which metrics we use, the results are not open to debate: reduced sea ice makes it harder for polar bears to catch food.

In the Beaufort Sea ice region, the ice coverage is already less robust than it once was. And that means that the bears must cover greater distances just to access the seals they need. In other cases, the bears have been forced to forage for sea bird eggs, an adaptation that doesn’t provide the energy they need.

This research, like studies before it, clearly demonstrates that polar bears’ futures are inextricably linked to melting sea ice. Esteemed polar bear researcher Dr. Steven Amstrup told the Guardian:

Every piece of evidence shows that polar bears are dependent on sea ice and if we don’t change the trajectory of sea ice decline, polar bears will ultimately disappear. They face the choice of coming on to land or floating off with the ice as it recedes, out to the deep ocean where there is little food. We will see more bears starving and more of them on land, where they will get into trouble by interacting with humans.

While President Trump  claims that sea ice is setting new levels, the latest scientific research demonstrates that sea ice is declining quicker than ever before. The Arctic, in particular, faces global warming at double the pace of the rest of the world.

In a very real way, this study offers a glimpse into the possibly devastating impacts climate change could have on our planet’s biodiversity.

Photo credit: Thinkstock.

77 comments

John W
John W3 months ago

This is what I despise about Liberals, you act as if you're on the side of science and are the morally enlightened ones. It's nauseating

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John W
John W3 months ago

President Trump might be wrong about climate change and video games causing violence. However, your side is against GMO and nuclear technologies, believe in homeopathic remedies and organic farming nonsense.

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HEIKKI R
HEIKKI R3 months ago

thank you

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David C
David C4 months ago

how sad

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Angela K
Angela K4 months ago

Thank you for sharing

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KimJ M
KimJ M4 months ago

:( tfs

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KimJ M
KimJ M4 months ago

Tfs

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KimJ M
KimJ M4 months ago

Tfs

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Dan Blossfeld
Dan Blossfeld4 months ago

Mark Donner,
Actually, I suspect that I have a much better understanding than you. In the overall schemes of things, yes, this has been a slight increase.

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Mark Donner
Mark Donner4 months ago

Steve F: This isn't "natural selection" It's a massive artificial assault on the planet by an unnatural force.. humans are not part of an ecosystem, and it's idiocy to state that they are. And Earth's biosphere is not some kind of god that will absorb your insanely massive chemical and physical attacks. The cancer called humans CAN destroy that biosphere with their unnatural crap so that it never recovers

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