Climate Change & Anthropocene Extinction 37: If the sea ice goes, so does the Arctic ecosystem

All life forms that depend on Arctic sea ice will be hurt when that sea ice disappears. And especially when you also depend on other life forms that depend on sea ice. Polar bears are an obvious example (and if you go a bit deeper humans are also included).

We’ll skip the humans and talk about polar bears in a bit, but let’s first talk about the underlying issue: what science means – and how it’s actually quite easy to harness your own intelligence to interests that may want to try to confuse you. Yes, a scientific mind – a joy forever.

Arctic marine ecosystem: many species (inter)dependent on sea ice - including polar bears
Schematic representation of the highly specialised Arctic marine ecosystem and the various (groups of) organisms that are interdependent – and either directly or indirectly dependent on the presence of sea ice. Image from ‘Current state and trends in Canadian Arctic marine ecosystems: II. Heterotrophic food web, pelagic-benthic coupling, and biodiversity’, a 2012 ecological study by a Canadian research group, published in the journal Climatic Change.

If you have basic scientific understanding, you know that in order to project the future development of –well– anything from the complex real world, you have to have understanding of the development of driving root causes.

Your alternative, extrapolating your current observations, is so primitive it’s not even bad science – it’s not science. And of course what’s worse still, is extrapolating not all observations, but instead a careful selection, stripping away both the underlying context of scientific understanding and the surrounding context of a wider view on all available data.

If you use incomplete sets of climatic data stripped of scientific context – anything goes: global cooling, sea level stagnation, you name it

That’s an often-used tool for those that hope to fabricate argumentation to support pre-existing (political) agendas. If somehow it’s in your interest to argue the Sun does not exist, just take a picture each night to prove your case. Without context, anything goes. Climate deniers are a clear example.

We’ll present a couple illustrations before we’ll get to the actual publication we hope to discuss – one that compares methodology of science-based and ‘science-denying’ climate websites but that also touches on a subject we personally find far more interesting: what’s actually going on in the Arctic, an area that is not only experiencing major physical consequences of climate change, but that is subsequently also set to be a stage for a cascade of ecological consequences of this climate change – both in the Arctic tundra biome and in the adjacent Arctic marine ecosystem.

Non-scientific lines of argumentation denying scientific climate consensus. Number 1, temperature:

Core business for climate deniers is of course first to try to argue that either the world is not warming, or that it is warming at a slower pace than climate scientists state (the distinction between the flat-out deniers, a dying breed, and the lukewarmers category).

Not touching the physical foundation of anthropogenic warming, scientific knowledge since the age of physicists and chemists like Fourier (greenhouse effect, 1822), Tyndall (heat absorption greenhouse gases, 1863) and Arrhennius (rising CO2 will cause global warming, 1896) these people simply hope to override the science by showing alternative temperature graphs.

This goes for global temperature: cherry-picking a favourable part of a trend line (preferably an ENSO-overrepresenting dataset) – for instance the acclaimed plateau between the 1998 El Niño and the 2010 La Niña, or even worse, a local cold winter.

Apart from (deliberately) excluding part of the available data, it is ignoring the underlying physical science – the fact that rising atmospheric concentrations of greenhouse gases cause warming. The full global temperature datasets illustrate this, but the underlying physics explains it. That’s the science(!)

Number 2: If you exclude ice sheet dynamics and global temperature rise, sea level rise isn’t so bad…

Another clear example from climate science is sea level rise. What climate deniers do is point to observations of sea level rise (these can actually go down locally for several years, following cyclical patterns) and then often say ‘hey, it’s 2 or 3 millimetres per year – so that’s 20 or 30 centimetres in a century’ (or less, if they choose to cherry-pick half of a local natural cycle). Now 20 or 30 centimetres is enough to cause trouble on Pacific islands and densely populated river deltas like Bangladesh, but the real-world future will be worse.

Presenting such alternative figures confuses and undermines the public understanding of the actual science, which is an understanding about the driving mechanisms of sea level rise: thermal expansion of ocean water, melting of mountain glaciers and complex dynamics of large ice sheets – in correspondence again with projected temperature rise, that is in turn a product of projected rises of greenhouse gas concentrations using calculated estimates of climate sensitivity, together creating a net disturbance in Earth’s energy balance, the very root cause of anthropogenic climate change.

If you understand these very complex issues – and fortunately the world’s scientists, by working together and being their own best sceptics do(!) – you understand that sea level rise will not continue on a linear line, but that it is set to accelerate – very much within this century. [How much? That’s subject of an actual scientific debate, in which the actual climate scientists (including glaciologists) participate. Very interesting, and very important.]

Lastly, what goes for physical consequences of course also applies to the ecological consequences of climate change – root causes are drivers of trends

Now there are endless other examples in which the consequences of climate change depend on other consequences of climate change. We’ll end with this one, that’s perhaps the most obvious to understand: if a sea-ice habitat completely melts away, the survival of all the species that are dependent on this sea ice, directly or indirectly, is threatened. This goes for the Arctic – and for the many species in the very specialised Arctic sea ice ecosystem, from ice-specialised Arctic crustaceans and tiny swimming shellfish that Arctic fish depend on, to the (already sharply declining) Arctic hooded seal and the (still abundant) ringed seal that lay their cubs on the sea ice – and eventually also for polar bears, for which ringed seals are a prime food source.

It is how ecology works: once you disturb an ecosystem beyond a certain threshold, you create a cascade. You can’t precisely predict beyond which threshold and how or how quickly this cascade will unfold, but you do know – as long as stressors keep building up – that it will happen (and exponentially, when you talk about climate and biodiversity).

Internet Blogs, Polar Bears, and Climate-Change Denial by Proxy

Now to the new study, published on Wednesday in the journal Bioscience. It uses diverging reporting about the faith of the polar bear as an example to describe the difference in methodology between science communicators and those trying to spread misinformation, illustrating a split between ‘climate denier blogs’ and science-accurate websites, when such internet media talk about the same topic.

The study, titled ‘Internet Blogs, Polar Bears, and Climate-Change Denial by Proxy,’ was performed by a mixed group of 14 ecologists and climatologists led by Jeffrey Harvey of the Netherlands Institute of Ecology (NIOO-KNAW) and further including climate scientists that are known for engaging the public spread of misinformation like climate researchers Bart Verheggen of Amsterdam University College and Michael Mann, of Pennsylvania State University.

Science-based versus climate-denier blogs on Arctic sea ice
Comparing the reporting of science-based versus climate-denier blogs on Arctic sea ice. If you strip the scientific context of a globally rising temperature trend, you could argue that observed melting of sea ice is just some noise in the data, part of natural variation.

First of all, let’s make sure you understand that you are currently on a blog – and what’s worse, a blog that tends to write about the issue of climate change. The problem with blogs is that anyone can start one, anyone can step on that tiny self-created online platform and claim to be some sort of authority.

This of course does not go for academic positions at climate research departments or meteorological institutions. There you have to prove you actually know about the topic, before you become entitled to talk about it – years of study, years of hard work, scrutinised by others that put in even more years of possibly even harder work. It’s the scientific world. If first assessing data, then drawing conclusions is not your preferred sequence of events, then you will not make it in this world. Also, it doesn’t hurt to be very smart.

Enough about actual scientists [they always want all the attention!] – back to the blogs:

Blogs offer a perspective, scientific publications offer evidence

Although our website carries the beautiful name Bits of Science and as an author of this piece I would love you to believe every word I write, please don’t. Blogs, also science blogs, offer a perspective; scientific publications offer evidence. That’s a big difference.

Now a good science blog tries to communicate the evidence that scientists present. Therefore you’ll see them link to the actual peer-reviewed publications in established journals when they discuss these studies. You as a reader can click on that link, and see if the blog post is in line with what the researchers are saying – and if somewhere along the line some journalistic freedom is taken, at least it’ll be transparent. That’s good, that’s what you should want, as a reader.

Bad science blogs want to create their own reality. These very often don’t link to actual peer-reviewed publications, but rather prefer to create a swamp of words and as discussed in the beginning of this post some cherry-picked data – a mess of misinformation, for you to drown in.

Now we thought we were clever by writing the above evaluation of the landscape, but then we read the actual publication we’re trying to discuss – and again those pesky actual researchers were one step ahead, writing the following:

“A blog is a website that contains regularly updated online personal ideas, comments, and/or hyperlinks provided by the writer (Nisbet and Kotcher 2013). The Internet is open to public use, and individuals or organizations can set up blogs and promote their perspectives on virtually any topic, irrespective of their societal importance or validity.”

Let’s agree we agree.

The authors of the Bioscience publication present examples of climate-denying websites. [Some of these websites claim to be well-known, but it probably depends on what side of the Atlantic or Pacific Ocean you live whether you’ve ever heard of them.]

“Despite the growing evidence in support of AGW, these blogs continue to aggressively deny the causes and/or the projected effects of AGW and to personally attack scientists who publish peer-reviewed research in the field with the aim of fomenting doubt to maintain the consensus gap.”

Now fortunately, there are also different blogs – actual science-based blogs as opposed to science-denier blogs:

“Although science-based and science-denier blogs may draw on similar examples, they frame their claims differently. For example, scientific blogs provide context and associated evidence, whereas denier blogs often remove context or misinterpret examples.”

Unsurprisingly, fundamental differences in methodology lead to strongly diverging conclusions. And that’s illustrated if you compare how ‘science-based’ and ‘science-denier’ blogs discuss right about any climate-related topic, from actual atmospheric temperature development to its physical manifestations, like sea level rise (see the chart in the middle of this piece) and social and ecological consequences of climate change – including at some point the fate of iconic mammal species that use sea ice as hunting grounds. Yes, polar bears – targeted as a ‘keystone domino’ for attempted ‘climate-change denial by proxy’:

“Polar bears (Ursus maritimus) are […] a prominent focus of blogs in the debate over AGW [anthropogenic global warming] and its biological effects. Because polar bears depend on a habitat that literally melts as temperatures rise, these animals are iconic symbols of the negative effects of AGW.”

“At the same time, many denier blogs pay little or no attention to the volumes of physical evidence for AGW and the empirical biological and ecological evidence of its effects. Because this evidence is so overwhelming, it would be virtually impossible to debunk; the main strategy of denier blogs is therefore to focus on topics that are showy and in which it is therefore easy to generate public interest. These topics are used as “proxies” for AGW in general; in other words, they represent keystone dominoes that are strategically placed in front of many hundreds of others, each representing a separate line of evidence for AGW.”

“By appearing to knock over the keystone domino, audiences targeted by the communication may assume all other dominoes are toppled in a form of ‘dismissal by association’.”

Are polar bears threatened by climate change?
Are polar bears threatened by climate change? Science-based blogs say yes, obviously, their habitat is disappearing; climate-denying blogs say no, which fits there hypothesis that climate change is not happening, therefore sea ice is not (really) melting.

So, what is going on in the Arctic? Yes, rapid warming and sea ice melting

It’s been a while since we last reported on Arctic sea ice conditions, during the record-hot Arctic winter of 2016 to be precise, partly because it’s so obvious what’s going on that we don’t consider it a cutting edge for climate science communication. Others clearly think otherwise.

Any time you want an update, simply visit the website of the US National Snow and Ice Data Center (NSIDC) – there you can find daily satellite measurements and monthly trend analyses, like the one shown below (comparing average sea ice extent for October 2017 to all other Octobers in the satellite record, illustrating a downward trend). Other leading sea ice data sources are NASA, NOAA and the University of Bremen.

Arctic sea ice trend October 2017, NSIDC
Arctic sea ice October trend. According to NSIDC the sea ice extent in October 2017 was the fourth lowest on record.

Due to dominance of various positive climate feedbacks, the powerful albedo effect in summer and somewhat weaker and lesser-known warming feedbacks in winter, the Arctic is the most rapidly warming region on Earth – a phenomenon known as Arctic Amplification.

The comparative speed of Arctic warming (approximately three times the global average) was strongly illustrated in a new latitude-dependent temperature rise graph (that we discussed in our recent piece about Sahel greening as a consequence of this hemispherically ‘skewed global warming’).

Linear melting, or accelerating melting? Despite many positive feedbacks, there seems to be support for both

Now the sea ice response is quite obvious – it is melting, and this melting will continue as average temperatures keep rising. The downward trend is however steeper in summer than in winter. So if you would base a projection on end-summer data only you may think the first summer ice free Arctic Ocean is only a couple of years away. Including annual winter recovery (when warming feedbacks are weaker) you may have a more linear development and get back to a decades-timescale, as this NASA study suggests. Within multi-annual variation, sets of years of sea ice recovery are also possible, sea ice-climate models show. But the same goes for the possibility of sudden drops, below the actual trend line.

As sea ice melting progresses further other positive feedbacks may grow stronger though – most notably progressive sea ice thinning, that increases sea ice surface vulnerability to both weather extremes of warming and storm conditions and therefore a sea-ice dynamics feedback. Another progressive positive melting feedback could (paradoxically) be increased inflow of saltier water.

Now, finally, to “the faith of the polar bear” – a species like any other, influenced by a myriad of environmental factors, including bullets and melting sea ice

In this series we’re trying to investigate the role of climate change as one several drivers of the global extinction crisis. Often we find other extinction drivers are more imminent. Partly this is because it’s hard to beat the blunt biodiversity effects of direct habitat destruction (like deforestation) and partly that is because climate warming is often a slow process, for instance in the deep oceans, where its ecological effects are ‘outpaced’ by the rapidly escalating plastic pollution – admittedly an impossible comparison.

We hope to illustrate that when it comes to ecological consequences we don’t think climate change is always the number one threat. If you look at overall biodiversity projections under continued 21st century warming there is however good reason to be very concerned.

And in some instances climate change is both a rapid process and something that equals habitat destruction. This goes for the Arctic.

Polar bears as a species are doing quite well. Their habitat however…

The IUCN estimates that there are currently (2015) between 22,000 and 31,000 individuals. Some populations have rebounded following hunting regulation, other populations are decreasing, but because especially statistics from the Russian Arctic are inconclusive, the overall trend is unknown, the IUCN states. (The polar bears themselves are shrinking in size though, possibly due to warming-induced malnourishment.)

The scientific approach is however to try to include context to observations. This goes for the physical world of climatology (sea ice “doesn’t melt structurally” when you ignore the context of temperature rise; temperature doesn’t rise when you ignore greenhouse gases). And when you include the realm of ecology to the process of climate change the complexity only increases further, having to take into account inter-species dependence and competition, and highly unpredictable effects of ‘biodiversity redistribution‘.

Habitat decline polar bears climate change
“Predicting The Future Distribution of Polar Bear Habitat in the Polar Basin from Resource Selection Functions Applied to 21st Century General Circulation Model Projections of Sea Ice” – US Geological Survey, 2007.

That’s why it makes more sense to zoom out and look at the physical conditions for an ecosystem, many of which are climatological: Will the Amazon rainforest continue to receive required amounts of rain? Will the geographic locations of Earth’s climate zones still correspond to their respective biomes?

Will the Arctic tundra remain tundra – and can a sea ice-dependent ecosystem count on the continued presence of sea ice? Those are the major questions, determining the faith of not one, but very many individual species.

Polar bears (Ursus maritimus) are listed as a marine mammal, because they spend most of their lives on the (frozen) ocean – and are dependent on sea ice for their specialised feeding. Sea ice loss therefore quite literally translates as habitat destruction. This leads IUCN researchers to list the species as ‘vulnerable’ – expecting substantial population declines over the coming decades:

“Our analyses highlight the potential for large reductions in the global Polar Bear population if sea-ice loss continues, which is forecast by climate models and other studies (IPCC 2013). Our analyses also highlight the large amount of uncertainty in statistical projections of Polar Bear abundance and the sensitivity of projections to plausible alternative assumptions. Across six scenarios that projected polar bear abundance three generations forward in time using the median and 95th percentile of estimated GL, the median probability of a reduction in the mean global population size greater than 30% was approximately 0.71″

Ecological climate inertia and non-linear declines

Often, again generalising ecological consequences of climate change, these effects lag behind warming – leading to ‘ecological climate inertia’, followed by accelerated declining beyond an ecological tipping point. In the case of polar bears this possible non-linearity in the response of populations to warming is discussed in an interesting 2004 publication in the journal Integrative & Comparative Biology:

“Spatial and temporal sea ice changes will lead to shifts in trophic interactions involving polar bears through reduced availability and abundance of their main prey: seals. In the short term, climatic warming may improve bear and seal habitats in higher latitudes over continental shelves if currently thick multiyear ice is replaced by annual ice with more leads, making it more suitable for seals. A cascade of impacts beginning with reduced sea ice will be manifested in reduced adipose stores leading to lowered reproductive rates because females will have less fat to invest in cubs during the winter fast. Non-pregnant bears may have to fast on land or offshore on the remaining multiyear ice through progressively longer periods of open water while they await freeze-up and a return to hunting seals. As sea ice thins, and becomes more fractured and labile, it is likely to move more in response to winds and currents so that polar bears will need to walk or swim more and thus use greater amounts of energy to maintain contact with the remaining preferred habitats. The effects of climate change are likely to show large geographic, temporal and even individual differences and be highly variable, making it difficult to develop adequate monitoring and research programs.”

Will the polar bear survive? Well, just think of what makes sense:

“All ursids show behavioural plasticity but given the rapid pace of ecological change in the Arctic, the long generation time, and the highly specialised nature of polar bears, it is unlikely that polar bears will survive as a species if the sea ice disappears completely as has been predicted by some.”

Earth is home to many billions of species – a majority of which will be affected by the unfolding Anthropocene Mass Extinction, of which anthropogenic climate change is one of the major, synegistic drivers.

In that respect it’s always been banal to centre the issue of climate change on the polar bear. But if you have to make it a poster species, then the most ridiculous thing to do is try to frame it as your keystone domino to convince the world of the flat-Earth-position of climate denial. It’s melting in your hand.

© Rolf Schuttenhelm | www.bitsofscience.org

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