Posts Tagged ‘Jeff Harvey’

How blogs convey and distort scientific information about polar bears and Arctic sea ice

December 22, 2017

Our article on sea ice and polar bears proved to be a hot-button issue in the blogosphere. This was not entirely unexpected, of course. What is striking though, is that amidst all the criticism nobody has challenged our core finding: blogs on which man-made climate change and its impacts are downplayed are far removed from the scientific literature, at least regarding the topic of shrinking Arctic sea ice and the resulting future threat to polar bears.

Even more so, alternative figures that have been prepared by some critics basically underscore this same message (see examples below). That’s not so strange of course, since the signal is so clear: there is hardly any overlap between contrarian blogs and the scientific literature on this topic. Take a look at the pie-charts below for the three statements on sea ice and those on polar bears, for the two different groups of blogs (termed denier and science-based blogs, respectively), and the peer-reviewed scientific articles that investigate both polar bears and Arctic sea ice. This is basically an extension of figure 1 in the paper, in which only the two blog categories were shown. Most scientific articles as well as science-based blogs assess Arctic sea ice extent to be shrinking and polar bears to be threatened as a result, and most denier blogs take a contrary view on both sea ice and polar bears. They are poles apart.

You may argue that it was overkill to use an elaborate statistical analysis such as PCA on this dataset. It was used mainly to visualize our results in one figure. All the criticism on the PCA and the details of how data were analyzed misses the forest for the trees: there is a clear distinction between blogs, where the group that accepts AGW appears to base their claims on peer-reviewed science, and the group that doesn’t accept AGW does not. The latter group appear to base their claims to a large extent on blogs written by one particular biologist, Susan Crockford, whose views run counter to the relevant ecological literature.

Our paper is first and foremost a characterization of the blogosphere, and how it compares to the scientific literature. We restricted our literature search to scientific articles that investigate both polar bears and sea ice, and that shed light on polar bear ecology and how it may or may not depend on the presence of sea ice. An article such as “Evolutionary roots of iodine and thyroid hormones in cell signaling” does not fit that bill, to name just one example of Crockford’s scientific articles that has been pointed out as evidence of her having published on polar bear ecology. She has not.

Even though it is not the main scope of our paper, we described the scientific context of polar bear ecology and explained how and why polar bears depend on their sea ice habitat (summarized in my previous blog post). As such, we argued that the scientific understanding of arctic sea ice decline and polar bear ecology is more credible than the viewpoints put forward on contrarian blogs. However, providing new ecological evidence was not the point of this paper. The point was to investigate how our current ecological understanding is conveyed and distorted in the blogosphere.

If some people think that our conclusion is wildly wrong, then they could at least show some evidence to prove their point, right? They probably realize that our conclusion is robust, so instead they try to nitpick on details and make it appear as if that undermines our conclusion. It does not.

 

Appendix: A collection of PCA graphs depicting our results, all basically underscoring the main conclusion that one group of blogs correctly conveys our current scientific understanding, while another group of blogs distort this understanding and promotes a very different viewpoint regarding sea ice and polar bears.

From top to bottom the following PCA figures are shown:

  • As published in the Bioscience paper, in which missing values are replaced by zero after scaling the data
  • List-wise deletion of all records with missing values, considerably reducing overall sample size
  • Using multiple imputation with logistic regression (5 rounds of 40 iterations each)
  • PCA figure of the same data as produced by Richard Tol, where sample size of each location in the graphs is depicted by symbol size
  • PCA figure of the same data as produced by RomanM at ClimateAudit, without information on sample size

As mentioned in the supplemental information with our paper, jittering was applied to our PCA figure to gently offset data with the exact same entries from each other for graphical purposes. Tol uses an alternative method to provide information on sample size for specific data entries, namely via the size of the symbol used in the figure. Whatever your preference, the conclusion drawn from these figures is the same: there is a clear gap between the consensus in the scientific literature and science-based blogs on the one hand, and contrarian blogs on the other hand. We thank Roman Mureika and Richard Tol for underscoring the validity of our conclusion.

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There once was a polar bear – science vs the blogosphere

November 29, 2017

Blogs on which man-made climate change and its impacts are downplayed are far removed from the scientific literature. That is the conclusion of a new article in Bioscience in which a variety of blogs was compared with the scientific literature regarding the shrinking Arctic sea ice and the impact on polar bears.

Although there is strong agreement within the scientific community about anthropogenic causation of recent climate change, a large segment of the general public has doubts about these conclusions. This is sometimes referred to as the ‘consensus gap’. Blogs and other social media play an important role in spreading misinformation, which fuels the distrust in science.

Jeff Harvey, a Canadian ecologist working at the Netherlands Institute for Ecology (NIOO-KNAW) and the Free University of Amsterdam (VU), set out to investigate how the information on blogs relates to the scientific literature. The focus was on conclusions about Arctic sea ice and polar bears. The results have been published in the article “Internet Blogs, Polar Bears, and Climate-Change Denial by Proxy” in the journal Bioscience. Disclaimer: I’m a co-author of said article.

So what did we find? There is a clear separation amongst blogs, where approximately half of the 90 blogs investigated agree with the majority of the scientific literature, whereas other blogs took a position that is diametrically opposed to the scientific conclusions. Most of the blogs in the latter group based their opinions on one and the same source: Susan Crockford.

90 blogs and 92 scientific articles were classified according to six statements about Arctic sea ice and polar bears and the citation of Crockford. The figure shows the results of a principal component analysis (PCA) of the results. PCA is a technique to show the maximum amount of variation in a dataset with a minimum of newly defined parameters, the so-called principal components. The score on PC1 shows a separation between on the one hand the position that Arctic sea ice extent is shrinking and that this poses a threat to polar bears (most scientific articles and science-based blogs) and on the other side the position that Arctic sea ice is not shrinking or that it’s due to natural variability and that polar bears are not threatened (pseudo-skeptical blogs).

Arctic Sea ice

Arctic sea ice has shrunk dramatically in the past few decades, both in surface area and in thickness. This trend is expected to continue with ongoing global warming as a result of greenhouse gas emissions. Of course the decrease in sea ice doesn’t happen monotonically, but rather with ups and downs as a result of natural variability. When it happens to fit their perspective, such short term fluctuations are framed as a ‘recovery’ on certain blogs, or the decrease in Arctic sea ice is downplayed in other ways.

Polar bears

Polar bears depend on sea ice for catching their main prey, seals. So their habitat literally melts away as temperatures rise. Over time, polar bears have become iconic symbols of the negative effects of global warming. The population has been relatively stable so far, but you can’t just extrapolate that to the future. Biological impacts are often non-linear, and their dependence on sea ice means that in the future polar bears will likely face difficulties from continuing warming trend. Indeed, they have been classified as ‘vulnerable’ by the International Union for the Conservation of Nature (IUCN) and as ‘threatened’ under the US Endangered Species Act.

“No climate report is complete without an obligatory photo of a polar bear balancing on a piece of ice”, John Oliver said in the famous 97% episode of “Last Week Tonight”.

But what about the previous interglacial?

The polar bear species has survived the previous interglacial ~125,000 years ago. Some deduce from that that the polar bear will be fine. However, if CO2 emissions aren’t drastically reduced temperatures will get a lot warmer over the coming centuries and even millennia than during the previous interglacial. Moreover, during the previous interglacial summers were probably not completely ice-free, as is expected to happen  later this century as a consequence of continuing warming (which of course depends on how global emissions evolve). The current warming trend is many times faster than back then, making potential adaptation to new conditions more difficult. Besides shrinking sea ice there are currently also other factors that negatively affect polar bears, such as human settlements, industrial activities, hunting, bio-accumulation of toxins, and smaller seal populations.

Blogs

A future with ‘business as usual’ emissions doesn’t look bright for the polar bear. Blogs appear to fall into two camps in how they write about this topic. On pseudo-skeptical blogs scientific uncertainty is twisted into ignorance, or the current situation is extrapolated into the future without taking into account the available knowledge of polar bear ecology. They usually don’t base themselves on the scientific literature, but rather on the statements of one person. These rather unfounded opinions are consequently recycled via the blogosphere, which in this respect acts as an echo-chamber. Susan Crockford writes a lot about polar bears, but does so mostly on her own website and for anti-mitigation thinktanks such as the Heartland Institute and the Global Warming Policy Foundation (GWPF); not in the scientific literature.

The gap between scientific conclusions and pseudo-skeptical blogs will not be a great surprise to those who closely follow both the scientific and the public debate about climate change. After all, this tendency is more generally visible than only on the topic of Arctic sea ice and polar bears. This is however the first time that this has been demonstrated on the basis of a systematic comparison between the scientific literature and blogs. To close the consensus gap the authors call on their fellow scientists to actively participate in the public debate.

Zie de Nederlandse versie op ons klimaatverandering blog.


Updates:

The Supplementary Information that was part of the paper submission is still not available on the OUP website despite our repeated request to do so asap. In the meantime you may download the SI here. The data (scores per blog and per scientific article) are available via Dryad.

There has been quite some media attention for this study. Below an incomplete listing (for Dutch pieces see the abovementioned link to my Dutch sister-blog).

Polarised debate: polar bear blogs reveal dangerous gap between climate-change facts and opinions (NIOO press release) (reposted at several other places)

New study uncovers the ‘keystone domino’ strategy of climate denial (The Guardian)

Writers behind climate-change denial blogs ignore science, study finds (Toronto Star and many other Canadian newspaper outlets)

Polar Bear Blogs Denying Climate Change Are Being Used to Spread Conspiracy Theories Around the Globe (Newsweek)

Revealing the Methods of Climate-Doubting Blogs – Study shows that climate-skeptic bloggers often use limited disagreements to cast doubt on the big picture. (InsideScience)

Climate Change & Anthropocene Extinction 37: If the sea ice goes, so does the Arctic ecosystem (Bits of Science)

80 Percent of Climate Denier Blogs Reference This One Canadian Zoologist (Vice Motherboard)

How do you Spot a Climate Science Denial Blog? Check the Polar Bears (DeSmogUK)

Polar Bears Chosen as a Bizarre Symbol to Deny Climate Change, Scientists Say (DeSmogCanada)

Nearly all climate-change denial blogs quote exactly the same dubious research (International Business Times)

Unsurprisingly, the article gave rise to very different reactions, which easily fell into two camps (sounds familiar?): “insightful overview” vs “stupidest paper ever”…

Biodiversity, extinction and climate change

February 19, 2011

The previous thread turned into a discussion on how climate change might affect biodiversity. It started with Jeff Id’s taunt:

A warmer world will produce more food, biodiversity and a nice place for people and critters to live. Polar bears might be mad, but life is hard.

Aftersome back and forth’s, with e.g. Dave H noting the apparent disconnect between a strong focus on uncertainty and such a strong statement about positive effects, ecologist Jeff Harvey chimed in:

high temperatures are not a pre-requisite for high biodiversity

He points out that an important factor for maintaining high genetic and species richness is

stability – that is, that conditions in a region are not altered frequently by some important extrinsic challenge, such as rapid local climatic changes. (…)

the current rate of warming threatens to seriously undermine the functioning of biomes and ecosystems through uneven effects on species within tightly interacting food webs. (…)

Our species has simplified the planet biologically through the combined effects of paving, ploughing, damming, dredging. logging. slashing and burning, mining, dousing in synthetic pesticides, biologically homogenizing (e.g. through invasive species), altering the chemical composition of the air and water, and through various other forms of pollution. We know that genetic diversity is being lost at rates unseen in 65 million years, and against this background we are challenging an already impoverished fauna and flora to respond to climate changes that are unprecedented in perhaps tens of thousands of years.

Jeff Id replies:

I think like so many tied up in the eco-sciences you have blended too many causes and effects together to attribute the micro-warming to anything damaging to the ecosystem. (…)

my point is that over the next hundred years of warm weather, it would certainly result in higher planetary biomass all other effects unconsidered. Higher biomass eventually results in higher diversity. Warm in general is good for the planet, if you do it slowly enough and not too much of it.

How fast and how much, we could argue all day.

I tried condensing Harvey’s points thus:

– Biodiversity depends more strongly on the rate of change of climate than on the actual climatic state (i.e. whether “warm” or “cold”).

– That is consistent both with evidence from the past and with theoretical considerations

– Biodiversity is already being stressed (by multiple anthopogenic stressors, of which climate change is one), and this stress is likely to increase as (the rate of) climate change will increase. (i.e. future projected biodiversity loss is much stronger than current biodiversity loss)

Of course, it’s a bit more cpmplicated than that, as Harvey aludes to in his reply. Later on he notes that

The IUCN (…) does not classify a species as being ‘formally’ extinct until it has not been recorded in the wild for at least 50 years.

And on the current rate of extionction:

We KNOW that between 10 and 40% of well-known species (vascular plants and vertebrates) are threatened with extinction.

This is an area that don’t know much about, so I don’t have much to add. It’s a very important aspect though, especially when taking into account that projected future (rates of) warming are much stronger than what we’ve seen so far. Not to mention that once a species is lost, it’s lost practically forever. I would think that the rate of species loss can be much greater than the maximum rate of new species development (or creation if you wish ;-).  

References on biodiversity, extinction and climate change:

Extinction risks from climate change

Coral decline threatens fish biodiversity

Papers on ecosystem response to past climate change

Kate at Climatesight on extinction and climate

Association between global temperature and biodiversity, origination and extinction in the fossile record

Recommended reading by Jeff Harvey


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