The Arctic - A "Miner's Canary"?

So then,

What has this got to do with me? Should I be worried?

It would be easy to get sentimental here by saying something like 'we're all citizens of this planet' etc etc, but I'll resist... for the time being! Basically, it matters to all of us because of the significance the Arctic is likely to have in the context of climate change during the coming decades. Although I've repeated it so many times during this blog, I'll say again that the Arctic is warming faster than any other area on the planet. The sea ice record is especially sensitive to temperature, and it has been reacting to the change at a remarkable rate, as we've seen.

In most of the world, biological responses to climate change cannot easily be separated from other things such as habitat loss and land use change, impacts which are potentially more severe. As the Arctic is far way from major populations, it gives an opportunity to see the impacts of climate change clearly, as these other factors are minimal (see assessment of pollution as a factor). Also, ecotones surrounding the Arctic are extremely sensitive as they lie on the very edge of possible habitation, meaning vegetation shifts have become apparent.

Therefore, it could be said that the changes seen in the Arctic over the last few decades are a warning sign, a miner's canary which is showing the first signs that it isn't feeling too great. It's showing signs of a relatively weak (in the context of land use changes etc in other areas) but persistent and growing force. If left alone, the potential for positive feedbacks through melting permafrost and ocean albedo effects would take the path of warming completely out of our hands. If that happens, we definitely should be worried.

As well as this, the political implications of what is happening in the Arctic may be even more pressing and potentially damaging. Tensions are already building between Arctic, and even non-Arctic nations about the resource scramble which is likely to happen now that new areas suitable for resource prospecting have been opened up. In an often cited example, in 2007 Russia planted a 1m high flag under the north pole in a symbolic move to lay their claim to resource rights in the Arctic. Of course, this significantly added to the tension surrounding the Arctic and geopolitics.

Russian flag planting mission, a global superpower laying it's claim to the billions of dollars
worth of resources beneath the Arctic.

Whether they like it or not, the environment is now an issue policy makers must act on. It will be interesting to see how things pan out from here in the Arctic. Hopefully some lessons will be learned, meaning climate change doesn't become an opportunity for further environmental damage. It should be clear then, that although the Arctic is out of sight, it would be unwise to put it out of our minds.
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As a final comment, I hope during the course of this blog I've managed to objectively comment upon the changes in

Wrapping up (2)

This is the penultimate post! (please, don't cheer too loudly). For the second half of the review (click here for the first part), I'm going to briefly consider some of the more tricky questions about the Arctic about the future. Of course, any answers are only based on past experience. It's impossible to tell what path environmental change in the Arctic will take, especially with the added complication of people who are even more unpredictable than the environment. So, here goes...

What is the likely impact of future human activity on aquatic and terrestrial arctic ecosystems?

It's only possible to extrapolate from what we know, meaning it's likely the changes seen in the past few decades are likely to continue. Also, natural systems exhibit lagged responses, especially when organisms take decades to grow. For example, shifts seen in aquatic ecosystems are very significant as they respond quickly to temperatures. Alterations to terrestrial vegetation, on the other hand, are slow, meaning the small changes evident in the past few years are probably responses to warming a few decades ago. Therefore, it's likely that aquatic communities will continue to shift with changing patterns of ice cover and benthic vegetation, woody (and perhaps even large vascular plants) will expand in extent, permafrost will melt and temperate organisms will begin to move north.

This is also a good point to bring up all the papers which I haven't had time to bring up, but indicate the potential for future changes in the Arctic as extrapolated from that seen in recent decades. In a great review article, Post et al. (2009) provided a short account of ecological responses to Climate Change in the Arctic. Changes with significant potential include range shifts (seen in moths), invasive species and phenology (see graph below).

Earlier flowering in Greenland (direct from Post et al., 2009)

Such movements in seasonality become problematic when there's a mismatch between producers and consumers. For example, a growing difference was observed between peak Caribou births and peak productivity of

Wrapping up (1)

Unfortunately, it's almost time for this blog to come to an end, so for the last couple of posts I'll try and sum up what I've learned over the course of the past couple of months. At the beginning I posted a few questions that I wanted to answer, so I think these are a good place to start, so I'll use these as a structure for the next couple of posts.

How do we know the sea ice retreat in the past few years is unusual?

The blog started off by looking at this question, firstly by using satellite data. Since satellite data began in 1979, sea ice extent and thickness have been decreasing at an alarming rate. Sea-ice extent during the summer of 2011 (sept) was almost on par with the previous record low during 2007, even without the unusual weather patterns thought responsible for the 2007 low. This strongly suggests that even though sea ice doesn't decrease every winter, overall conditions are worsening for continued survival of permanent sea ice.

A number of proxy records show a sea-ice history going further back than any contemporary records. As part of the blog, I looked at two relatively new methods of constructing these histories; the IP25 biomarker and Quartz records. These, as well as other methods, including documentary and ice-diatom records, show that extent of sea ice has been strongly variable, but also strongly correlated with climate. Sea ice extent is therefore extremely sensitive to temperature changes, meaning if we were experiencing global warming today, we could expect a significant loss of sea ice. Is that what we've been seeing?

Well, the sea-ice is disappearing at a faster rate than any model used by the IPCC has forecast, even the pessimistic 'business as usual' scenarios shown on the graph below. The graph doesn't show the past 5 years, but if it did the trend would be continuing, with 2007 being the minimum.

Sea ice extent output values from 13 IPCC Global climate models with an ensemble mean in thick black.
Actual observations are shown as a thick red line. Direct from Stroeve et al 2007.

Of course, this means a few things could be happening. Firstly, there could be some unknown natural variability that

Recent warming of Arctic Water (AW)

Just a short post about a short article from Science which was published in January. Spielhagen et al (2011) counted assemblages of planktonic foraminifera from a 14C dated core taken from the West Coast of Svalbard, with a resolution of around 18 years, higher than previous works. In total the core was found to cover c.2000 years. Planktic foraminifers typically grow between 50-150m ocean depth and the 'bloom peak' is around August meaning these records are of summer ocean temperature. Estimates of temperature were calculated by a statistical comparison of assemblages found in the core to a modern dataset of foraminifera assemblages from areas with different environmental conditions. It's hoped that by using this Modern Analogue Technique (MAT), it's possible to match up two similar assemblages, and it's assumed that conditions which determine the two aren't going to be that much different. Clearly, the assumptions, and therefore possibility for error are pretty big, so results have to be pretty significant to be meaningful.

The results showed a large increase in temperature in the past c.150 years, which was unusual when compared to the past 2000 years, found to be similar to the observational records of the Arctic Atlantic Warm Layer (AAWL). This strongly suggests that Arctic Water (AW) inflow from the Atlantic is warming, which has the potential to significantly speed up sea ice melt.

Of course, this is based on only one core, so this article is more of a call for more research rather than necessarily conclusive findings. It will be interesting to see if the significance of these AW changes can be de-tangled from all the other influences of Arctic sea-ice levels.

Melting Permafrost - should I be worried?

Just before getting started, I found the video I really wanted to share with you guys before, but ended up using a replacement. It's from the fantastic series 'Earth: The Power of the Planet', presented by the brilliant Prof Iain Stewart, a Geologist at the University of Plymouth. He's like Geology's answer to Brian Cox! If you missed the series, I'd encourage you to have a catch-up. Interestingly, this video also features the same Dr Walter as the previous video..

Although it's the easiest and most spectacular way of showing the processes which are happening, it's not the lakes that are causing the most concern. Phrases like 'ticking time bomb' and 'unstoppable warming' are used

Treeline in the Arctic

As promised, I'm going to consider the Arctic Treeline for this next post. Just as a warning, one of the papers I use in this post includes some sites from below the 66 degrees latitude level, so I hope you'll forgive the slight digression from our brief.

An alpine treeline in the background. Although not an Arctic treeline,
the clear change illustrates the concept well.

Firstly, what is the Arctic treeline? As an intuitive general definition, a treeline separates regions where tree-growth is sustainable, and areas where climatic factors such as low temperatures prohibit the establishment

Shrubland expansion - photographic evidence

To start off the posts on terrestrial ecosystem change, I'd like to share a short (one page!) correspondance article from Nature by Sturm et al (2001). It's pretty simple and is completely qualitative based on only two 'observations', but it's interesting nonetheless. The authors found high quality photographs, taken during oil reserves exploration in 1949 at around 68° latitude in the Alaskan Arctic. By taking 66 modern photographs at some of the same locations, they could compare the vegetation cover at the same sites over the 50 year period. Here's one of the comparisons:


A hillside in the Alaskan Arctic in 1949 and 2000. A and B show identical locations.

Although a crude assessment, it is clear that there is a difference between the two photographs. Abundance

Arctic Lakes and Zoological Indicators

As we saw in the last post, it is highly likely that climate is indirectly altering Diatom communities in high Arctic lakes through changing levels and patterns of ice cover. Quinlan et al. (2005) used the same cores as the (previously reviewed) Douglas et al. (1994) study and counted the fossil chironomid (non-biting midge) larvae remains down the cores to investigate whether invertebrate communities have also 'shifted', and if they have, how likely it is that the changes are linked to the results from the previous diatom investigations. It's important to note, however, that these results are only taken from three archives (ie lakes and ponds) from Ellesmere island so further study is required to confirm that these findings are widespread.

Chironomidae are a family of flies which are aquatic organisms until their adult stages (see above) and

Arctic Lakes and Diatom Change - A Brief Summary

As promised, I'm going to cover the Smol et al (2005) article this time, as well as some associated references which will form part of the discussion. This post will focus on the Diatom changes seen in a wide range of Arctic lakes and their inferred causation. It's generally accepted that the Arctic regions will experience the effects of climate change disproportionately to other regions. This, coupled with the sensitivity of Arctic lakes, (potentially) makes this form of study an early indicator of the speed and severity of climate change in the future on a global scale. (Oops, I may have partly answered the final question). Oh well, on with the post...

A subarctic lake from Northern Quebec

Arctic Lake ecology is nice summarised by Smol and Douglas (2007) and shows that

Thresholds and tipping points? - Arctic lake 'regime shifts'

For the next post I'm going to be reviewing an article by Smol et al (2005) entitled "Climate-driven regime shifts in the biological communities of Arctic lakes". So before I launch into that, I thought it would be best to have a review of the ecological theory surrounding what they are calling 'regime shifts' by looking at the article they reference. Ecological shifts can occur naturally (such as through fires) or, as is more likely in recent times, due to human activities. Click 'Read more' for a proper explanation...

Conceptual diagram of regime shifts and alternative
stable states. Direct from Scheffer et al (2001)

The C25 HBI Monoene AKA "IP25" biomarker in marine sediment cores - a valuable contribution?

I know at the end of the last post I promised a move away from palaeoclimate studies to ecosystem change, but there's a couple of subjects I've recently come across that I thought would be interesting to consider before moving on (sorry!). The first one is the use of IP₂₅ from Marine sediment cores to reconstruct a history of ice extent in the Arctic region.

Skeletal formula of the IP₂₅ biomarker

Using the Arctic Proxies (past 2Kyr)

As mentioned at the end of the last post, palaeo-records are not perfect, and the way to ensure the best picture is to compare multiple proxies in aptly-named multi-proxy studies. A recent such synthesis study focussing on average temperature changes in the arctic is Kaufman et al (2009) ‘Recent Warming Reverses Long-Term Arctic Cooling’. A discussion of this and related articles will hopefully go some way towards answering the question of how we know recent warming is unusual.

The authors of this study combined the results of 23 palaeo-records with at least a decadal resolution from the arctic region. Seven ice core, 4 tree-ring and 12 lake records were included, with the lake records incorporating sedimental and biological indicators*. These data were taken from various individual studies, allowing a synthesis reconstruction of past temperatures extending 2Kyr BP. A strong cooling trend was found until around AD1950, likely caused by decreasing solar insolation (here a product of precessional cycles, see past the jump), and assertion backed up by a Community Climate System Model run in the same study.

What’s clear post-1950, however, despite the continuous insolation trend, is an upward spike in most of the proxies. Tree-ring records exhibit the most sudden and significant response, with lake records showing a large but more gradual trend, likely the result of the differences in annual resolution between the two proxies:



'2000' relates to AD2000, therefore warming taken place in past 100yrs.



The ice core data, however, is more perplexing, and under initial investigation suggests a further cooling trend. Strangely, this feature is not commented upon by the authors in the published paper, although the nature of the journal may have limited the extent to which the results could be fully discussed. Despite this, combined results (in grey above) show an increase from a -0.5 to +0.2 (standardised to 900-1800yr period) temperature anomaly during the period 0 to AD1950, which increases further to +1.4 for the very latest records. The recent warming trend agrees with the global climate review articles shown below by Mann et al (2008) and Moberg et al (2005). The global reconstructions, however, show greater variability during the '1900 year cooling period', suggesting that the cooling trend appears to be confined to the Arctic caused by the dominance of solar forcing upon the regional climate.



(F) decreasing solar insolation recieved at the atmosphere in the arctic region caused by precession (G) synthesised reconstruction from this study shown in grey compared to global synthesis reconstructions.



In light of the past 2Kyr then, the recent warming trend in the Arcticis sudden at around 1950, and reverses the cooling trend of the past 2Kyr despite continued precessional forcing. It is clear from this study that the recent warming is unusual and has been clearly registered on a number of proxy records around the arctic. The extent of this synthesis is only 2Kyr, however. In the next post I'll look at a few papers to get an idea of the Arctic climate throughout the Holocene.

Out of sight, out of mind?

Last month (Sept 2011) marked the end of the summer maximum in the northern hemisphere, and the total sea ice extent change data is beginning to emerge. This year’s summer extent was on a par with the record low of 2007 (since satellite records began in 1979) despite weather conditions being less favourable to sea ice loss than in that year. The National Snow and Ice Data Centre (NSIDC) remote sensing records on sea ice extent for the past few years are shown below:

http://nsidc.org/images/arcticseaicenews/20111004_Figure2.png

It is clear from this that recent summer, and to a lesser extent, winter ice extent is far below the average of the past 30 years plus two standard deviations. It could be said then, that the ‘climate’ of sea ice in the region is changing.

Overall, the far north is changing faster than almost anywhere else on earth. For this reason, it is likely that the arctic region is going to give the best warning signs as to the rate and severity of global climatic change. I will try in this blog over the coming months to engage with (and hopefully come to some conclusions about) important questions surrounding the change in the arctic regions, namely:

How do we know the sea ice retreat registered by satellite data in the past c.30 years is unusual?

Are any changes apparent in terrestrial and aquatic arctic ecosystems?
Is anything else apart from rising temperatures causing change?

What is the likely impact of future human activity on marine and terrestrial arctic ecosystems?

Will changes in the Arctic have an effect on the global climate? 
What has this got to do with me? Should I be worried?

Even if you have no interest in the environment (but if you’re reading this I’d expect, and indeed hope that you are) the changes facing the arctic regions are likely to have severe economic, cultural and (geo)political impacts. Although a ‘cold’ war is unlikely (despite scare stories in the media), human activities such as patterns of transport and resource use are likely to be affected. Indeed, geopolitical wrangling has been going on for some time (eg Russian flag planting mission).

The aim of this blog is not to discuss solutions to rising CO₂ emissions and climate change, but rather to see how arctic ecosystems have been and continue to be changed by climate changes and occasionally give examples of how this is likely to affect human activities. This will be done by discussing studies on past change, current measurements and future predictions.

Please feel free to disagree, argue with or debate anything I’ve written (as long as they’re at least mildly constructive!) by commenting.