The complex science behind viral images of starving polar bears

A recent viral video positioned polar bears as the face of climate change, but the full impact of climate change on Arctic ecosystems goes beyond just one species.

Just as panda bears were once the face of the endangered species crisis, the polar bear has long been considered the poster child for the impact of climate change. This status as an environmental icon was demonstrated in National Geographic's top-shared post of 2017, a viral video featuring an emaciated polar bear staggering across iceless land in northern Canada.

The video was viewed over 30 million times and opened with the line, "This is what climate change looks like." However, many people – including some of the world's leading Arctic researchers – found some of the claims in the video to be misleading.

Dozens of researchers have documented dramatic declines in polar bear populations in the past several years due to disappearing sea ice. Todd Atwood, lead biologist on the United States Geological Survey (USGS) polar bear research program, has been studying the Beaufort Sea polar bear population for six years.

"The science is pretty clear," Atwood said. "The primary threat to the long-term persistence of polar bears – regardless of the particular part of the Arctic – is the loss of sea ice habitat, which is obviously being driven by warming air and sea-surface temperatures [from climate change]."

However, a study by Climate Feedback, a nonpartisan, nonprofit science fact-checking site, found that some of the claims made in National Geographic's video weren't entirely accurate. The study labeled the video "Neutral," on a scale of "Very Low" to "Very High" scientific credibility.

Climate Feedback's reason for this score was that the video implied that climate change was responsible for this particular polar bear's condition, rather than for a general decline in all polar bear populations.

As Atwood explained, "It's tough to take a single image and say, 'This bear is dying from climate change and this is the fate of all bears,' because what the science tells us is there are some sub-populations that are doing well, some are even increasing, and some are doing poorly. From a science perspective, that's exactly what we expect to see. The public sometimes doesn't appreciate the nuances because in a lot of messaging the nuances get lost."

Ecosystem health – especially in Arctic regions under the effects of climate change – is a complex science that, according to Paul Wassmann, a marine Arctic researcher in Norway, would "need a textbook" to explain thoroughly.

"[Arctic marine ecosystems] are impacted by far too many ways and by all means: warming, stratification, wind impact and storm tracks, river discharge, pollutants. The short answer is: [they have been impacted] severely."

With all of this complexity, it can be impossible to accurately portray the nuanced science behind something like polar bear declines in a two-minute viral video.

Ecosystems are made up of complicated, delicate food webs. If an important organism, called a keystone species, is removed from this food web, the ecosystem becomes significantly unbalanced and the whole web can fall apart. Keystone species can be as small as microscopic phytoplankton or as large as whales and polar bears.

Polar bears prey almost exclusively on seals. In an increasingly warm planet, the sea ice that polar bears rely on to hunt seals is disappearing, and as it does, polar bears have started coming to land in search of food.

"Beginning in the late 1990s, in summer and fall, ice was retreating further and further beyond that continental shelf, separating bears from their food," Atwood said. "Now we're seeing upwards of 25 percent come to shore…[and] they're not only coming to shore in greater proportions, they're also staying longer."

Polar bears normally hunt by waiting for seals to return to holes in the sea ice to breathe, but on land, bears are forced to hunt in open water or on the rocky shores, which is more difficult and often less successful. As this sea ice recedes, polar bears are losing access to food. This is what most scientists believe is the leading cause of polar bear population decline throughout most of the Arctic.

Though researchers are confident about broad trends like these being a result of climate change, ecosystems are so complicated and interconnected that it's very difficult to know with certainty what causes specific impacts – such as starvation – to occur to certain individual animals, like the polar bear in National Geographic's video.

Another more nuanced aspect of the science behind this video stems from the fact that, unlike other ecosystems that have suffered from declines in predatory keystone species, the decline of polar bears isn't the only decline happening in the Arctic. The entire ecosystem's home – the sea ice – is also disappearing.

"The marine Arctic ecology is complicated and diverse. While all major organism groups are connected to each other," Wassmann explained, "They are [mostly] all connected to ice."

This interconnectivity has made it increasingly difficult for scientists to understand where the effects of ice melt end and the effects of specific species like polar bears begin. Yet as difficult as this is for scientists, it's even more difficult for journalists and activists trying to explain this complexity to a general audience, especially since, to many people, polar bears are the most recognizable species in the Arctic. All arctic species – from microscopic phytoplankton to massive orca whales – are increasingly endangered by melting sea ice, but polar bears are still considered the face of climate change.

Wassmann believes this could be due to the fact that stopping climate change to save bears is more galvanizing to the public than the idea of saving something like krill or arctic cod.

"All arctic species are vulnerable due to warming, by definition," Wassmann said. "[But] ice algae, copepods, capelin? Would you care about those?"

When journalists use the condition of iconic species like polar bears to explain global issues like climate change, the complexities of ecosystems and climate science are often lost and miscommunication can snowball into broader misinformation.

"I understand why it happens," Atwood said. "[Journalists] want to communicate a message in a concise way that people remember, but I think the nuances are important."

People like Becky Hazen,  associate director of SciLine, an organization that connects journalists to scientific experts around the world, strive to get these nuances to appear in the news as often as clear messages about issues like declines in polar bear populations do.

"That's the mission," Hazen said. "Working with reporters to get the [science in] the story right…The public should have access to information that is evidence-based, and I think where that can come from is better connections between reporters and scientists."