Sir David Attenborough recently lent his voice to a new Netflix series, “Our Planet,” that documents human impacts on the planet, with a particular focus on climate change. Unsurprisingly, climate change contrarians were unhappy about this series and seized any opportunity to criticize it. The criticism that has gained the most traction revolves around a scene of walruses falling off of cliffs. According to the documentary, they were forced onto those cliffs because of a lack of sea ice and their deaths are, therefore, a result of climate change (i.e., a lack of sea ice forced them onto land, where there was little space, resulting in some climbing the cliff and ultimately falling to their deaths [walruses are not well adapted to cliffs]). Climate change deniers took issue with this and insisted that the documentary was fraudulent and it was actually polar bears that killed the walruses. I was tempted to leave this situation alone (and I’m admittedly late to this controversy), but it perfectly displays so many different flawed lines of reasoning and deceptive tactics that I think dissecting it will be instructive (also, no one impugns the honor of Sit Attenborough without me having something to say about it).
The person behind the controversy
To begin with, we should meet the person who started this fuss: Dr. Susan Crockford. She (as far as I can tell) started this on her blog “Polar Bear Science.” Crockford is a self-proclaimed polar bear expert. She is also a climate change denier who has stated that temperatures are not rising significantly and frequently argues that polar bears are doing just fine and will adapt to any decrease in arctic ice. As a result, she is a favorite source for those who deny climate change, and she is frequently cited as an expert who disagrees with the consensus. She also frequently writes articles for the Global Warming Policy Foundation (a pseudoscientific think tank) about how well polar bears are doing. Additionally, she was on the payroll of the Heartland Institute (another climate change denying group).
Here’s the thing though, she’s not a polar bear expert. Indeed, she isn’t an expert on anything even remotely related to climate change. She is an adjunct professor of anthropology (not someone who holds a research position), and, as of this writing, she has published exactly zero peer-reviewed research articles on polar bears. She is not a polar bear researcher. She doesn’t work with them.
On her blog, she states, “I am a different kind of polar bear expert than those that study bears in the field but having a different background means I know things they do not and this makes my contribution valuable and valid.” That is, however, utter nonsense. You can’t just decide that you are an expert on something. That’s not how expertise works. By way of example, I do a lot of research on turtles. I have years of research experience and multiple publications on them. As a result, I get to call myself a turtle expert. In contrast, someone who has never studied turtles and never published research on turtles does not get to call themselves a turtle expert, and they don’t get to assert that not doing actual research has somehow allowed them to know things that I (and other actual experts) missed while doing all of our actual research. You can’t just decide that you are an expert on something. That’s not how this works. Think about it this way, every fact we know about polar bears was found by someone actually studying polar bears. Thus, she cannot magically know things that those people don’t, because they are the ones who discovered everything we know.
Indeed, an actual polar bear expert, Ian Stirling (who, amusingly, she compares herself to) said that she has “zero” authority on polar bears.
I’m taking the time to explain all of this for three reasons. First, this strategy of claiming that a non-expert is an actual expert is an extremely common tactic among climate change deniers and science deniers more generally. They present people like Crockford as bonafide experts so that you will take them seriously when they say something like, (paraphrasing) “polar bears aren’t declining,” but Crockford is not a polar bear expert and claiming that she is one is a lie. She is a quack and a fraud who is mascaraing as an expert.
Second, this arrogant notion that not doing actual research actually makes someone more knowledgeable/qualified is pervasive among pseudoscientists, and it is absurd for all of the reasons I have just explained. You can’t just magically pull previously unknown information out of thin air, and this concept that not being a real researcher is somehow beneficial is utterly insane.
Third, the source of a claim or accusation can help you judge the level of skepticism that you should apply. It is not, in and of itself, enough to determine what is true and what is false, but it is a useful starting point. If, for example, a claim is coming from someone who is an actual expert or who, at the very least, has a well-established record of veracity (like, say, Sir David Attenborough) then you have pretty good reason to think that the claim is likely true. You should still fact check, but the burden of proof is fairly low. In contrast, if a claim comes from someone with a long history of being untrustworthy, then the burden of proof is quite high, and you should be very dubious until you are presented with really clear evidence. In this particular case, the accusation is coming from a non-expert with a known agenda, known connections to science-denying groups, and a long history of making false claims about her expertise. In other words, not a trustworthy source.
To be fair to Crockford, several newspapers did report that two people with more relevant expertise (Lori Quakenbush and Lori Polasek) had questions about the sequence, seemingly largely because such events have been known for decades (more on that in a minute). However, neither of them appear to be making the type of bold accusations that Crockford is making, and their comments are sparse enough that it is hard to say much about them, so I’m going to focus on Crockford’s assertions (note also that other experts have supported the description of events in the documentary).
Note 2: Just to be 100% clear, actual experts and actual studies strongly disagree with Crockford’s rosy assessment of polar bear populations. I talked about this with sources here.
The documentary’s claimed
Let’s look at what the documentary actually claimed. It showed a large group of walruses in what is known as a “haul-out,” where they come on land to rest. It explained that this would usually happen on ice shelves, but as the arctic ice melts, walruses are being forced to use land. It then asserted that limited space sometimes forces walruses to climb high cliffs to get away from the crowds. Then came the really disturbing footage. It showed walruses falling off the cliff to their death and said that this was happening as they attempted to return to sea (it mentioned that walruses have poor eyesight). It attributed these deaths to climate change by arguing that the walruses were only up there because of a lack of sea ice which was the result of climate change.
So what is Cockford’s issue with the sequence? The underlying issue is simply that she is a climate change denier and is, therefore, unhappy about a documentary highlighting the very real damage that climate change is doing. As a result, she and her supporters have been citing the fact that walruses haul-outs have been reported for decades and there are previous reports of them falling from cliffs. Thus, according to them, this is not a result of climate change.
More specifically, she argues that the walrus deaths in the documentary were actually the result of polar bears driving the walruses off the cliffs. Indeed, she insists that the crew was filming a previously reported event where polar bears drove walruses off a cliff. The crew of the documentary has denied that polar bears were responsible for the deaths that they filmed, but Cockford insists that they are lying.
Evidence and bad arguments
There is a lot to unpack with Cockford’s claims, and they illustrate quite a few logical blunders and flawed tactics, so let’s go through this.
First, let’s get some facts straight. We have known for a long time that walruses will haul-out onto land but prefer to use ice (Fay 1982). We have also known for a long time that these haul-out events can result in mortalities from trampling, falling off cliffs, etc. It is true that this is not a new phenomenon. That does not, however, automatically mean that climate change is not playing a role in current haul-outs and subsequent deaths. Indeed, the argument being used by Cockford is simply a variation of the classic (and flawed) climate change denier argument that if something happened naturally in the past, it must be happening naturally now. That logic is a non sequitur. It’s not logically valid. The fact that something happened naturally in the past does not mean that the current occurrence is natural, and what scientists are actually reporting is that climate change has increased the frequency and size of haul-outs. In other words, there would naturally be a low background rate of these events, but climate change is increasing them.
So, where is the evidence for that? Well, we know that terrestrial haul-outs primarily occur when there is little sea ice (Chadwick et al. 2008), we know that climate change is greatly reducing the amount of sea ice available (Meier et al. 2007; Stroeve et al. 2012), and we know that haul-outs can be dangerous for walruses (Chadwick et al. 2008; Fischbach et al. 2009). The logical conclusion is, therefore, that climate change will result in larger and more frequent haul-outs, ultimately resulting in more deaths, and that is what seems to be occurring (Jay et al. 2011; Jay et al. 2012). Indeed, Maccracken (2012) reported that since 2000, the number of walruses using terrestrial haul-outs in the Chukchi Sea (the area where the documentary was filmed) has increased by an order of magnitude.
Side note: “Maccracken” is the best name for a marine biologist ever.
So, where does this leave us regarding the accuracy of the documentary? Attenborough’s facts were correct. Global warming is reducing sea ice, which is causing walruses to increase their use of haulouts, which does result in mortalities. To be completely fair, it is impossible to say with 100% certainty that climate change caused the particular haul-out the documentary filmed, but it is likely that it influenced it, and it is true that climate change is making those events more frequent. So, I really don’t see anything wrong with what the documentary presented.
Moving on, what about Cockford’s assertion that it was actually polar bears that drove the walruses off the cliff? This is a great example of a straw man fallacy that totally misses the point and is designed to confuse people rather than point out a serious issue (it is another common tactic of deniers). Consider, for example, her statement,
“We know that walruses reach the top of cliffs in some locations and might fall if startled by polar bears, people or aircraft overhead, not because they are confused by shrinking sea ice cover.”
This is an absurd statement and, indeed, reveals the irrelevance of her whole argument. No one said that the walruses jumped because they were “confused by shrinking sea ice cover.” The documentary claimed that they jumped while trying to return to the sea, not because they were confused by the lack of ice. Further, the reason for the jump is actually irrelevant. The relevant question is simply, “why were they up there in the first place?” In other words, let’s assume for a minute that Crockford is right and polar bears drove them off the cliff, that wouldn’t change the fact that that walruses are increasingly climbing cliffs because of climate change! In other words, that would only change the proximate reason they jumped, not the ultimate reason they were on the cliffs in the first place (i.e., climate change). Thus, her entire argument is a huge distraction. Whether or not polar bears were present is 100% irrelevant, but by making a big deal about it, Crockford distracts people from the real problem: climate change is forcing walruses to go on land and put themselves in dangerous situations.
Finally, we need to talk about the burden of proof and Crockford’s logically invalid attempts to shift it (another classic anti-science tactic). Crockford has boldly asserted that the crew is lying and polar bears were the proximate cause of the walruses jumping. The crew has responded by saying that polar bears were not driving the walruses that they filmed off the cliff. So, who bears the burden of proof? The burden always lies with the person making the claim (or accusation). In other words, if someone accuses you of a crime, they have to prove that you are guilty, rather than you having to prove that you are innocent. Thus, Crockford must prove that the crew is lying, rather than the crew having to prove that they are telling the truth. Crockford, of course, can’t do that, which leads her into several blunders.
First, she said, “The crew and WWF can show I’m wrong by providing evidence of where the Netflix film footage was shot.” This would, according to her, either prove or disprove that the crew was filming the documented case of polar bears driving walruses off a cliff that I mentioned earlier. At a quick glance, that may seem reasonable, but it is actually an invalid attempt to shift the burden of proof. It is insisting that the crew has to prove their innocence, rather than her having to prove their guilt. That’s not how the burden of proof works.
Second, when the crew refused to reveal their filming location (as is common practice) she said, “I can only conclude, therefore, that the two incidents are indeed essentially one and the same.” This is a logical blunder known as an argument from ignorance fallacy. This occurs when you use an absence of evidence as evidence for your pet position. The fact that we don’t know where they filmed doesn’t automatically mean that it was the location Crockford says it was. Rather, it simply means that we don’t know. Similarly, it is invalid to assume that they aren’t revealing the locations for deceptive purposes (again, scientists and documentary crews frequently don’t reveal precise locations for conservation purposes).
In summary, the documentary showed walruses climbing a cliff and ultimately dying during their attempts to get down. Although these haul-out events have been known for a long time, climate change is making them more frequent and increasing the number of walruses present at them. It is, therefore, completely fair to say that climate change is contributing to walrus deaths from these events and Attenborough was correct to bring attention to that. The arguments to the contrary are bringing assumptions rather than facts, ignoring the ultimate reason the walruses were on the cliffs, and attempting to shift the burden of proof. Further, these accusations are being made by a known climate change denier who pretentiously claims to be a polar bear expert despite having never studied polar bears and having zero expertise on climate change.
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- Chadwick et al. 2008. Pacific walrus response to arctic sea ice losses. USGS 2008-3041
- 1982. Ecology and biology of the Pacific walrus, Odobenus rosmarus divergens Illiger. North American Fauna 74: 1–279.
- Fischbach et al. 2009. Enumeration of Pacific walrus carcasses on beaches of the Chukchi Sea in Alaska following a mortality event, September 2009. USGS 2009-1291.
- Jay et al. 2011. Projected status of the Pacific walrus (Odobenus rosmarus divergens) in the twenty-first century. Polar Biology 34:1065–1084.
- Jay et al. 2012. Wlarus areas of use in the Chukchi Sea during sparse sea ice cover. USGS Marine Ecology Progress Series
- Maccracken 2012. Pacific Walrus and climate change: Observations and predictions. Ecology and Evolution 8: 2072–2090.
- Meier et al. 2007. Wither Arctic sea ice? A clear signal of decline regionally, seasonally and extending beyond the satellite record. Annals of Glaciology 46: 428–434.
- Stroeve et al 2012. The Arctic’s rapidly shrinking sea ice cover: a research synthesis. Climate Change 110:1005–1027.