"But we almost had an Elfstedentocht this year!"

Hello there,

And as we continue on our round-trip through cold places, we now end up in the Netherlands. A very excited, anticipating, hopeful Netherlands, every single winter. The reason for that is one of my favourite collective Dutch obsessions, besides our football team and Queen's Day. It's a phenomenon called the Elfstedentocht, or 'Eleven City Tour', which is an almost 200 km ice skating tour on the frozen canals between eleven towns in Friesland, in the North of Holland. The first tour was in 1909, and since then we've had 15 tours, the last one being in 1997 (elfstedentocht.nl).

The relatively small amount of tours is due to the high ice quality necessary; a minimum of 15 cm thickness over the whole trajectory (Official Elfsteden Site). Because this doesn't take place often, gaps between tours are as large as 20 years. Still, as soon as the canals in Holland start freezing over for a few days, and temperatures stay below zero, the fever starts and people start speculating and hoping for another tour. Without fail, you will find newspapers filled with 'expert opinions' on the likelihood of an Elfstedentocht this winter and barely contained excitement. This one, for example. (Dutch - sorry)

The Tour's Route, beginning and

ending in Friesland's Capital:

Leeuwarden. Source

If you want more info on this wonderful tour, which I'm just introducing to you before

I start talking about its relationship to climate change, check out this awesome BLOG.

Pure Dutch Excitement - Source

So, what does this have to do with climate change? Well, talk to a Dutch sceptic about it and you'll hear the following argument: "But I don't notice the global warming at all! We almost had an Elfstedentocht this year!" It's a common confusion between weather and climate, and considering natural variability in temperature proof that climate change isn't happening.

In order to combat the misconceptions that having an Elfstedentocht means climate change is a myth, or that due to climate change, we'll never have a tour again, the KNMI (Royal Dutch Meteorological Institute) published the following article in 2001. It quotes the IPCC scenario that temperature will rise 1.4 to 5.8 degrees C between 2001 and 2100, and relates this to ice thickness.

The mean winter temperature (December-February) between 1980 and 2000 was 3.3 degrees C in the Bilt, where the KNMI is located (KNMI, 2001). This is significantly higher than the mean winter temperature between 1880 and 2000, which is 2.5 degrees C. The research correlates winter temperature with maximum ice thickness in Friesland, and the figure suggests a linear relationship. The research finds that with every degree C in winter temperature rise, the maximum ice thickness decreases with 5.4 cm (KNMI, 2001).

Relationship winter temperature (Y-axis) and 

max. ice thickness in cm (x-axis). Red dots

indicate years of an Elfstedentocht. Source

In order to test the linear relationship, the team employed seasonal hindcasting methods in the programme HISKLIM by Brandsma et al. (2000) for the period 1901-2000, meaning they retrospectively predicted the ice thickness in Friesland for all years, knowing their winter temperatures. From this, they got a result of 38 potential Elfstedentocht Winters (Brandsma et al., 2000) and (KNMI, 2001).
The reason for the discrepancy between the 38 potential tours, and the 15 that happened, is the importance of the course that winter takes. For thick ice one needs subzero temperatures, but in addition to that, the temperatures need to be continuously subzero, there can't be any snow and there needs to be little wind in the early stages. Also, logistic difficulties and cracks in the ice due to unidentified events lead to difficulties in organizing the tour (NRC, 2000).

The KNMI then also extrapolated these data to construct the scenario for the 21st century and calculate the amount of potential tours according to the IPCC 2001 scenarios. Their results are displayed in the figure below (KNMI, 2001). Even though since then, two more IPCC reports have been published, the upper and lower boundary of temperatures rise have remained the same - only the certainty has increased - so this figure still holds.

Chances of an Elfstedentocht in the 21st Century.

Relative change (in %, meaning ice thickness in

Friesland >15 cm) on y-asix, years on the x-axis. The colours

express the different IPCC temperature rise scenarios, ranging from 1.4 C to

5.8 C in 2100. Source

Finally, this means that even for the lower boundary scenario, Elfstedentochten will become even more rare in the next century. But along with so many other Dutchies, I will keep hoping for one, because this again is one of these wonderful parts of many people's lives that I don't want to see vanish due to climate change. 

'Invisible' Warming: Permafrost Decline

Hi all,

As usual, we're moving around the globe with these posts. So from the circumpolar arctic, back to the Swiss Alps. Today's topic of permafrost decline is obviously connected to cold regions and winter seasons, but not as visibly obviously impacted by climate change. Still, it's important to know of the various effects permafrost decline could have.

Permafrost is permanently frozen soil, which momentarily covers around 6% of the Swiss Alps (Schnee u. Lawinenforschung Schweiz), the majority of which is found at elevations of 2400 m. above sea level. The wording 'frost' implies the involvement of ice, but this is not necessarily the case because the classification of soil as permafrost solely depends on temperature ((Nyenhuis, 2005). The exact definition is disputed, but it is soil of any type that over the course of one year, according to Haeberli (1990) or two years, according to French (2007, first published 1996) has displayed continuous subzero temperatures (Nyenhuis, 2005).

If warming of these regions due to climate change continues, a rapid decline in permafrost cover will be observed in the next decade (Schuur et al., 2008). To correctly predict the development of permafrost cover, there is extensive monitoring in the Alpine countries. In Switzerland alone, data is collected since 1996, at over twenty monitoring stations located between Engadinn, over the Gotthart Area, and Wallis (SLF Permafrost Research Group). This research is lead by the SLF - the Snow and Avalanche Research Center in Switzerland. Their acquisition of correct data is essential to develop numerical models simulating future soil temperature. Since intensive monitoring, interesting patterns have been discovered, e.g. that observed temperature in permafrost, at a depth of at least 10 m. has a typical reaction time of six months. So a particularly warm summer such as the one in 2003 only has an effect the following winter. The yearly variation is very clear in figure 1.

Figure 1. Soil temperatures in several >10 m depth

boreholes in Switzerland, measured on 04.07 between 

1996 and 2008. Source: SLF Permafrost Research Group

So why is it even remotely interesting or important to monitor whether cold soil is staying cold? There are inevitable dangers resulting from the warming of permafrost (Haeberli and Beniston, 1998). "Permafrost degradation in fissured rock walls is likely to have long-term impacts on frost weathering and rock fall activity by reducing the strength and increasing the permeability at depths of meters to tens of meters." (Haeberli and Beniston). Especially when buildings stand on and are secured in a permafrost surface, there is an increased risk of collapse (SLF Research Group Permafrost). This can lead to dangerous situations, which is why research in this area is often passed on to instances responsible for alpine safety. Also, the Snow and Avalanche Research Centre has developed guidelines on permafrost avalanche building and since 2009, also for other types of building development in order to protect tourism and energy security in the Alps.

Finally, this small summary of permafrost shows once again that climate change in seemingly insignificant areas has physical as well as socioeconomic impact. Enjoy the cold in London and elsewhere, and see you here soon!

Snowball effect: Climate Change and Polar Bear Population Dynamics

Hello all,

Today's post will focus on another species that will be directly affected by climate change: the Polar Bear, or Ursus Maritimus (Durner et al., 2009). The link between climate change and danger for polar bear survival was first discussed in 1993, by Stirling and Derocher. They are still the most cited experts in the field and have both published multiple papers on the various aspects of this issue.

Figure 1: Polar Bear, to illustrate what we're talking about. 

Source: Stanford Blog

Figure 2: Their habitat

Source: Polar Bear Science

Polar bears' habitat is the sea ice near shore, throughout the circumpolar Arctic; the polar region around the North Pole (Derocher et al., 2004). Their preference is for dynamic sea ice of which the ice plateaus constantly shift, giving access to gaps of open water called Polynyas, (Stirling, 1997). They vary in shape and size and are the product of several factors, including upwellings, current, wind or a combination of these (Stirling, 1997). These polynyas are the polar bears' main hunting environment, where they catch their most important source of food: ringed seals. For the latter, polynyas are the main habitat, with a necessity for easy access to larger ice surfaces to give birth to and nurse their offspring (Stirling and Derocher, 1993). In order for both these species to exist in a stable equilibrium, the existence of sea ice and polynyas is essential (Stirling, 2002).

However, climate change impacts their future species survival due to vanishing sea ice. There are several climate models that predict the extent of future arctic sea ice, which is difficult to model and thus there are differences between the results of individual studies. The overall consensus however, appears to be that "overall, climate is warming, total ice cover is decreasing at a significant rate, and that large parts of the polar basin may be largely or completely ice-free in as little as 100 years" (Derocher et al., 2004). Empirical evidence shows that between 1976 and 2006, sea ice declined with an annual average of 8.6%, and 2007 being the record year with the lowest extent of summer sea ice (Serreze et al., 2007). These are all indications of change affecting polar bear habitat: earlier annual ice break up, and later freeze up ((Derocher et al., 2004), shifting the seasonal activity for polar bears and seals.

For polar bears, late spring and early summer is the period most crucial to survival. It is the time they do on-ice feeding on seals, storing body fat for the on-land period of fasting. When ice patterns progress as indicated above, the hunting period becomes shorter while the fasting period becomes longer. Also, due to increased drifting, the distance between ice plateaus will become larger and thus moving within its habitat will become more energy-consuming (Durner et al., 2009).
Derocher et al. estimated, based on averages from research in the Hudson Bay area, what this would do to the polar bear's ecology. Their results indicated that due to body mass loss, by 2100, most female polar bears would not have enough body fat to produce viable offspring, leading to extinction of the species (Derocher et al., 2004).

This is likely going to be accelerated by the non-availability of seals, whose population will decline because of lack of space for safe offspring bearing (Durner et al., 2009). This relationship between seal productivity and polar bear reproduction was already observed by Stirling in 2002. It is a commonly observed relationship in population ecology, made more comprehensible by the Lotka Volterra Predator Prey Model, though McLaren and Smith, 1985, warn the reader against its oversimplicity and lack of spacial parameters. Still, it is worthwhile in developing an understanding in the Polar Bear - Seal population dynamics and I'll do a brief discussion below in order to show you how all-encompassing an effect the sea ice decline will most likely have.

I am assuming some knowledge of the Lotka Volterra Model or a similar coupled differential equation model here. For an explanation, I recommend you refer to the following PAPER by Baigant, based at UCL. 
For an interest in mathematical ecology and population dynamics in general, I recommend Pastor's book Mathematical Ecology of Populations and Ecosystems. (Do mind: it's on its first edition, so includes many small mistakes in the equations. The theory is very thoroughly explained.) 

Figure 3: the Lotka Volterra Equation in its simplest form. 

Source: SOSMath

In which: 
R= Polar Bear Population Density
a= Polar Bear Growth Rate
alpha= Probability of killing a seal
F= Seal Population Density
Beta = probability of killing x polar bear's efficiency of conversion into biomass
b = random death rate

As is illustrated by the equation and what the symbols represent, a decline in sea ice will impact the population dynamics in various ways.
The decline of seal habitat influences productivity, thus F its population density, and alpha and beta, due to the altered polar bear's probability of killing seal.
The polar bear's mass, which as explained above will decline and lead to less offspring, impacts a the polar bear growth rate.
This all will have a total effect on the two population densities, and thus shift the equilibrium, potentially away from a stable coexistence equilibrium.

Time will tell how both polar bears and seals will (cease to) exist with declining sea ice. I hope you enjoyed the post and it got you thinking on the 'snowball effect' of climate change: its impact on one species affects another.

Who needs snow?!

Hi all, a little different this time: just a few fun facts I'd like to share with you!


Fun Fact I - For the ones not too familiar with the snowsports industry: you don't actually need snow to ski or board.

Also: the melting snowman is back!
(Because I have a camera phone again and 

can photograph drawings..)

Fun Fact II - Dry slopes, made up of dendex mats, are an alternative to snowsports on actual snow. Dendex is plastic and metal formed into brushes, which mimic the characteristics of snow. It makes it possible to practice in summer and in regions that don't have the right climate or are too flat. Also: snowboarding AND sea view AND environmentally much friendlier than artificial snow in indoor halls.

This is the Hillend Dry Slope in Edinburgh, where we spent

a great competition weekend with freezing weather but 

a great view. What do you think, viable

alternative to snow? 
Is this THE alternative for snowsports future when the Alps are no longer white? 

Fun Fact III - It's not all positive... due to higher friction and stiffness of the material, skiing or snowboarding is much more difficult on these slopes.

Fun Fact III - Falling is also much more painful than on snow - this I have researched extensively.

Fun Fact IV- Edinburgh was freezing this weekend, and we saw the first snow of the season. Wet, sticky, didn't last for more than a minute - but it was snow!

Just have a look at the sky please.. Proper Scottish Weather

Fun Fact V - The UCLU Snowsports Society did an awesome job at the British University Dry Slope Competition in Scotland this weekend, the largest dry slope event in the world (!). We had fun, we did our best, and we didn't win anything, but that's OK. I'm happy, proud and tired, and definitely looking forward to real snow. But until then, I'm glad dry slopes exist so we can train every week, even in snowless London.

Wine from Winter, a thing of the past?

Hi all,

Now moving from the permanently cold regions of the last posts to cold seasons, in this case: winter season in Germany. Besides always causing mayhem to public transport, the German cold winters also produce a lovely product called 'Eiswein', or ice wine. This is a wine produced from grapes that are left on the vine after the summer, to be harvested between November and February after they have frozen (Cliff et al., 2002). Harvesting has to happen quickly and by hand, in the very early morning after a few consecutive nights of temperatures below -8 degrees C. It is risky, because it requires for this deep frost to happen before the grapes rot. Using these frozen grapes results in a very sweet, more concentrated dessert wine, famous in Germany. Here, ice wine is only allowed to carry the name when it's produced in the traditional manner I just described (German Patent Office, to be viewed here), with the consequence that it's usually quite expensive. Cheaper versions are often produced in New Zealand, where artificial frosting takes places in cool houses (Jones, 2007). 

Not only a sweet product, but a gorgeous view. (Picture and article in German here)

However, this delicacy may be a thing of the past, at least for German production. Because of climate change, a topic most of you will be familiar with, the winter season in Germany has changed. The warming has led to a decrease in possible 'Ice wine days'. In the decade of 1979-1988, there were 254 potential ice wine days, while there were only 145 in 1989-1998 (Essen-und-trinken.de). In the last thirty years, there were only four years in which ice wine grapes could be harvested in November. 2001 and 2002 were the only years in the past decade in which grapes could be harvested in December, the rest was harvested in January and February (best-of-wine.com). 

This rise in winter temperatures has not only led to less production and economic loss due to rotten grapes before frost happened, but it also changed the quality of the ice wine. Because the grapes hang on the vine longer, their average acidity has gone down 2 promille and up 2 degrees of sugar compared to values before 2000. According to experts, this makes for a less round and traditional taste.

Research from the leading Geisenheim Insitute for viticulture also suggests the production of Ice wine will most likely become impossible in Germany over the next decade. (Source: Icewine Article (German) ) The majority of the production has already moved to Canada, because of more secure winters. 2006 was apparently an exceptionally good year, so if you're ever in Franconia and have something to celebrate - it's much recommended. 

While this may seem an insignificant topic, it does show what I expressed in my last post: climate change affects our everyday lives. Not because we drink ice wine every day, but because this is but one example of how climate change causes a shift in production, with economic implications for individuals and a tradition being lost. Food for thought? Let's have a drink and discuss this maybe.. 

Also - if all this talk inspired you to have a glass and a good meal, or you want to know more about environmental change in relation to what we consume every day, check out my friend Katherine's awesome blog RIGHT HERE - CLICK

Cheers and see you next time!

An 'in-between-post'

Dear all,

What many commenters have noticed is that in my posts, I often link climate change to my personal life and ideas. The reason for that is not that I enjoy talking about myself, but that I want to engage you as a reader. I would like you to translate the issues I address to the areas in your life that might be affected by climate and environmental change. I would like you to realise that climate change is not a 'ver van mijn bed show' (the incomparable perfect Dutch expression, the explanation of which you'll find here) but that its implications extend beyond a possible interaction with the topic in your professional life, into your everyday one.

To nudge you into that direction of thought, my next topic: wine. All of my readers are adults, and based on casual surveying among my peers, I think it is safe to say that there are several of you that enjoy the occasional glass... So check in soon for a new post on grapes and winter!