North-South glacier asynchrony during the Holocene

Well-constrained reconstruction of glacier activity during the Holocene epoch is difficult for a number of reasons, principally:

• (palaeo)glaciers are often located in harsh, high-altitude environments, which often lack sufficient productivity for radiocarbon dating;

• until recently, surface exposure dating techniques have lacked the precision to resolve the age of young landform formation (although see this study and this study);

• in the northern hemisphere at least, glaciers were at their maximum Holocene position relatively recently during the ‘Little Ice Age’ approx. 200-300 years ago, thereby removing any geomorphological record of previous glacier positions upvalley.

Holocene moraines denote former glacier position in Greenland (Humlum, 2000)

For these reasons alternative, indirect proxies of past glacier activity have often been sought. In a recent issue of Quaternary Science Reviews, Canadian-based authors Maurer et al. present a record of Holocene glacier fluctuation in British Columbia, Canada, using a sedimentary record from small mountain lake.

The reason this study caught my attention was the rather advantageous geomorphological setting, which allows the story of past glaciation to be told. The lake is located in a catchment which is currently unglaciated, but during times of more extensive glaciation the tongue of the nearby valley glacier extended into the lake catchment, providing inflow via glacial meltwater. When a glacier is present in the lake catchment the lake receives much coarser grained sediment than normal. Recognising this, Maurer et al. describe the past fluctuation of this glacier through the interpretation of a series of 3 lake sediment cores. They informally term the lake ‘On-Off lake’, presumably to reflect the numerous switches between glacial and non-glacial inputs. Radiocarbon dating of organic layers in the sediment cores and of tree remains in the glacier forefield provided the temporal constraint for identified glacier fluctuations.

Example of changing sediment types in sedimentary cores (source: https://sites.google.com/site/indigenouscultures/proxies-and-the-pa)

It was found that during the first half of the Holocene, from 10000-5000yrs before present, the local glacier was not extensive enough to provide input to On-Off lake. Tree trunks showing evidence of having been sheared by an advancing glacier were dated to approximatey 5000yrs old, representing the first evidence for local glacier advance during the Holocene. Between approximately 2750 years ago and the present day, the glacier front advanced and retreated over the On-Off lake drainage divide several times, as indicated by the switches between glacial and non-glacial sediments in the lake cores. Maurer et al. use historical photographs to supplement their geological record of Holocene glacier behaviour to the present day.

This study corroborates other records of northern hemisphere glacier activity, which show reduced glacier extent similar to / less than that of the present day during the early Holocene, followed by glacier expansion in the latter half of the epoch, culminating in the Little Ice Age maxima 200-300years ago. Recent studies in the southern hemisphere appear to show the opposite behaviour, with glaciers at their maximum Holocene positions in the middle of the epoch (approximately 6000years ago) and have undergone overall retreat ever since. These studies (link and link) suggest that this asynchronous behaviour between hemispheres is connected and caused by the changing position of the intertropical convergence zone (ITCZ). This climatic boundary shifts northwards and southwards over various timescales, predominantly in accordance with changes in the Earth’s orbit of the sun. During the Holocene the ITCZ has slowly shifted southwards, increasing the proximity of southern hemisphere glaciers, such as those in New Zealand’s Southern Alps, to warm, tropical airflows. At the same time, this tropical influence is therefore reduced in the northern hemisphere mid-high latitudes. Glaciers are highly sensitive to changes in atmospheric temperature, therefore it is suggested that these changes in ITCZ position and the respective control on regional air temperature are responsible for the differences in Holocene glacier behaviour between the hemispheres.

ITCZ temperature influence cartoon (source: http://phrederickvarga.blogspot.co.nz/)

These findings are interesting as they suggest that the controls on glacier extent can switch between regionally-dominant (such as that shown above for the Holocene) or globally-dominant (such as during the last glacial maximum approximately 210000years ago, when glaciers around the world advanced synchronously). As this study (link) points out, since the industrial revolution c.1850 AD, the majority of the worlds glaciers have been retreating in synchrony, likely due to rising temperatures in response to increased global greenhouse gas levels. Is this the case? If so, was global greenhouse gas concentration controlling the synchronous glacier behaviour during the last glacial maximum? And, what causes the switches between regional/global dominant controls on glacier behaviour? Further addition of well-dated, palaeoglacier and palaeoclimate records from around the globe will help to test hypotheses that aim to resolve these questions.

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The Younger Dryas

We have an interesting seminar here at VUW this Thursday (21/6/12), where Professor James Kennett will be speaking about the ‘Younger Dryas Impact Hypothesis’ (YDIH). In short, the YDIH suggests that approximately 12900yrs ago, an extraterrestrial impact or ‘fireburst’ in the North American region caused widespread fires, the extinction of the Clovis culture and contributed to the rapid, short-lived regional cooling event observed in climate records covering that time frame. I was an undergraduate student on an exchange at a Norwegian university when this theory was announced at and I remember watching the press conference (see video below) with my lecturers.

This is a controversial theory that challenges the longer held beliefs that the Younger Dryas resulted from the breakup of the last North American ice sheet. It is based on the discovery of a widespread carbon layer in sedimentary deposits that date to the start of the Younger Dryas at around 12900yrs ago. This is thought to represent the widespread burning that resulted from the extraterrestrial impact. The theory has sparked much debate and has also been widely criticized since it was announced at the AGU meeting in 2007. This went so far as a ‘requiem‘ being published for the YDIH. It will therefore be very interesting to here one of the original authors of the study talk to us firsthand about the evidence upon which this theory is based.

I will post another blog about the seminar next week, and if I remember to bring my generic tablet device I may even do one of those ‘live-tweet’ things on my twitter feed. In the mean time here’s a bit of background to the Younger Dryas….

The Younger Dryas

Following the peak of the last glaciation between 19000-26000years ago (commonly referred to as the ‘Last Glacial Maximum’ or ‘LGM’, the Earth’s climate was warming and the large ice sheets that had covered much of northern Eurasia and North America were retreating northwards. Similarly in the Southern Hemisphere, glaciers that had extended out from the mountain ranges such as the Southern Alps and the Andes were also retreating in response to the global increase in temperature. These climatic changes are thought to be caused by changes in the Earth’s position relative to the sun, which varies over known timescales.

Temperature change in Greenland from 23000-8000 years ago (Source:climateshifts.org)

Following the LGM, a number of more rapid (c. 1000-2000 yr long) cooling-warming cycles occurred, until global climate stabilised at around 11000yrs ago. These rapid events were first  identified in polar ice cores, where high-resolution records of past temperature changes are preserved in the layers of snow accumulation. The Younger Dryas represents one of these climatic events and covers a  period of time  approximately 1300 years long, between 12900 and 11600 years ago. It was first defined in fossil pollen assemblages in Scandinavia in the 1970s, where the relative abundance of pollen from plant species that inhabit cooler climatic zones increased, suggesting a decrease in local temperature. Subsequent work has shown that the Younger Dryas represents a period of dramatic cooling in the North Atlantic region, where a cooling of approximately 10degC caused glaciers to readvance in many parts of Europe and North America. One of these species is called Dryas octopetala, which is where the Younger Dryas gets its name (there is an Older Dryas, but that’s another story). The ice core records show that the Younger Dryas ended very abruptly, with rapid warming of several degrees occurring in a matter of decades. The fact that these changes occurred so rapidly and the fact that this occurred relatively recently (geologically speaking), has meant that the Younger Dryas is one of the most studied time-periods of the whole Quaternary. The main question surrounding this event is, ‘what caused it?’. The timescale over which it occurred is too short for it to have been caused by changes in the Earth’s orbit of the sun – as was the case at the LGM, therefore another explanation is needed.

Early work (and work still being undertaken today) focused on trying to establish the geographic extent of this cooling event (i.e. was it restricted to the North Atlantic, or was it a global event?), in order to try to identify the likely cause.  In the mid-1990s, radiocarbon dates of a glacial deposit suggested glacier advance in New Zealand during the Younger Dryas. The author’s of this influential study (cited 192 times and counting), interpreted this as meaning that the Younger Dryas was a time of global cooling and suggested that this was driven by changes in the atmosphere, which are rapidly translated around the globe. However, refined dating techniques, such as surface exposure dating, and a greater range of climate records now suggest that the opposite is the case and that the mid- to high-latitudes of the Southern Hemisphere actually experienced warming during the Younger Dryas, whilst the North Atlantic experienced cooling. This is also seen in polar ice cores where Antarctica is seen to experience warming whilst Greenland cools during this period.

 

The leading hypothesis for the observed differences in climate between the hemispheres during this time is known as the ‘bi-polar seesaw’ and was developed by eminent scientist Wally Broecker. Broecker recognised the role of the oceans in distributing thermal energy around the globe via density driven currents. In the early 1990s, following the development of the polar ice cores climate records (mentioned above), a correlation was made between these rapid cooling events and large inputs of freshwater (as recognised by marine deposits showing increased iceberg discharge) to the North Atlantic from the decaying North American and Eurasian ice sheets. It was suggested that these freshwater inputs altered the density of oceanic waters in the North Atlantic to an extent where the circulation slowed, therefore reducing the heat flux from the South to the North and causing cooling the North Atlantic region and warming in the Southern Ocean. This reconciles well with the interhemispheric asynchrony observed in glacier advance records (outlined above). No iceberg deposits are found to be associated with the onset of the Younger Dryas and initially Broecker hypothesised that the freshwater input associated with this event was sourced from Lake Agassiz, a large body of terrestrial water that was dammed by the former North American (Laurentide) ice sheet. However, later work  could not reconcile the timing of the main drainage of this lake with the onset of of the Younger Dryas. Other studies have identified a different route for the lake drainage, that appears to coincide with the onset of cooling.

In summary, despite the abundance of research that has focused on this time period, great uncertainty still surrounds the precise mechanisms that caused this dramatic climatic reversal. The ‘impact hypothesis’ presents another theory of the potential mechanism(s) that caused or contributed to the climatic changes seen at this time. Recently, Broecker and others have suggested that the Youngas Dryas is not a ‘freak event’ that it has long thought to be. They identify similar events in the ice-core temperature records of previous glacial-interglacial transitions and suggest that these short but intense climatic reversals are an integral part of the deglacial process. They conclude that “there is no need to call upon a one-time catastrophic event to explain the YD” which is a statement clearly leveled at the supporters of the impact hypothesis. Of course, it does not mean that there was not a meteorite impact at this time, but Broecker and others believe that the climate changes during the YD were driven by internal mechanisms. I look forward to hearing Prof. Kennett’s views on the whole subject…

IHQS research paper summary: Golledge et al (2012). Last Glacial Maximum climate in New Zealand inferred from a modelled Southern Alps icefield

This publication represents the most recent research output of an ongoing international collaboration between researchers from New Zealand, USA and Norway, which has been using the records of past glacier fluctuations in the Southern Alps to understand climate change from the Last Glacial Maximum to present (c.30ka-present). The first step of this project was to produce detailed maps of the local glacial geomorphology in order to document the past size and extent of glaciers in the Southern Alps (e.g. Barrell et al. 2011). The second step was to date these landforms in order to correlate deposits between glacier catchments and also to be able to compare results to other well-dated climate records of similar age (e.g. Schaefer et al., 2006; 2009; Kaplan et al., 2010; Putnam et al., 2010). This paper by Golledge et al. represents the third phase of this project, which utilises computer models to numerically simulate the past glaciers, from which, quantified estimates of past climate can be derived.

To do this, Golledge et al. use a complex numerical glacier model (called ‘The Parallel Ice Sheet Model’ or ‘PISM’, for short), which has been jointly developed by researchers at the University of Alaska, Fairbanks and Potsdam Institute for Climate Impact Research. This model uses physical equations that mathematically describe the different components of ice flow. Golledge et al. perform a series of experiments, whereby they manipulate the different glaciological parameters of the model (e.g. ice deformation and flow, internal and basal stresses) against the geomorphological evidence, in order to determine the most appropriate values. Once this is completed, the climatic variables (temperature and precipitation) are manipulated and compared to the geomorphological evidence, in order to provide an envelope of the likely climate change that caused glacier advance to the mapped and dated limits.

Figure 1: Modelled ice extent using temperature depression of 6degC (top) and 9degC (bottom) from the present day (Source: Golledge et al., 2012).

Figure 1 shows that the initial, low-resolution (2km grid square) model runs showed that a temperature decline of 6-7 degrees produced the best match between modelled ice extent (grey) and ice extent identified through geomorphological mapping (black line). The mis-matches at the margins of the various outlet glaciers are likely to be due to the coarse resolution of the model, where the outlet valleys are narrower than the resolution of the model run (2km). Narrowing down the likely temperature change at the time of this glaciation (e.g. 6-7degrees lower than at present), allowed Golledge et al. to maximise their computational efficiency in simulating the past icefield at much higher spatial resolution (500m). At this scale, they find that the optimum climatic conditions (i.e. those where the modelled ice best fits the geomorphological evidence) are a 6 – 6.5degC cooling, accompanied by a precipitation change of 0-25%, relative to the present day.

Comparison of these values to those derived from other palaeoclimatic proxies allows Golledge et al. to make inferences about the past climatic regime of the region. The temperature change compares favourably with those from other proxies. For example, temperature estimates from bacteria accumulations in LGM lake deposits suggested LGM cooling of 5.6degC in the Southern Alps (Zink et al., 2010). Meanwhile, regional numerical climate models suggest a cooling of 7.5degC (Drost et al., 2007). In comparing their results to past sea surface temperatures Golledge et al. find that their results are more aligned with those from sub-Antarctic influenced water masses (6.8degC) than sub-tropical (4deg C). They suggest that the local climate at this time was therefore still significantly influenced by southerly winds. Regarding past precipitation, Golledge et al.’s finding of potentially drier conditions at the LGM in New Zealand are consistent with other studies (e.g. Whittaker et al., 2011) that have suggested this was caused by a reduction in strength of the prevailing westerly winds across New Zealand, during the LGM.

In some ways this paper represents the culmination of many years work, from the initial mapping stages, through the development of high-resolution chronologies and now to a palaeoclimatic context. The significance of the terrific geomorphological records of past glaciations in New Zealand’s Southern Alps has long been recognised – as evident in the numerous and influential studies (e.g. Porter, 1975). Understanding regional climatic response to global events such as the Last Glacial Maximum allows us to better understand processes driving past climatic change and New Zealand represent one of the few landmasses in the Southern Hemisphere where such records exist. Future work will focus on improving the chronological constraint of glacier fluctuations in the region and using high-resolution, catchment-scale glacier models to better understand the responses of different glacier types to climatic forcing.

Cosmogenic nuclide dating, from a rock to a date…

The main objective of my PhD is to reconstruct the retreat of the Uummannaq Ice Stream System, a large system of coalescent ice streams in West Greenland.  To constrain the timing of the retreat of this ice, we are using a technique known as cosmogenic nuclide dating.

Cosmic rays, originating from outer space, bring  rare cosmogenic nuclide isotopes (I am using ¹⁰Beryllium and ²⁶Aluminium) to the Earth’s surface, where they build up in exposed rock surfaces at known rates. The total concentration of these isotopes in a rock surface therefore represents the length of time that the surface has been exposed to the atmosphere. This provides an ideal method for determining when a glacier retreated from a region, hence exposing the ground beneath. Technological developments in the last few decades have allowed more precise measurements of their concentration in terrestrial rock samples and this dating technique is becoming increasingly popular.

I collected the samples in the field in 2010 and 2011:

Rock sampling for cosmogenics at 900m a.s.l on Karrat Island

Rock sample after being cut with the rock saw

Having collected the samples in the field and received funding to run them, I went up to the Scottish Universities Environmental Reserach Centre (SUERC) laboratories in East Kilbride to start the process!

As 10-Beryllium and 26-Aluminium preferentially build up in quartz, the aim of the first week was to crush down the samples and extract as pure quartz as we could.  Firstly I had to crush the samples in the workshop to shards, and then grind them down on a disc miller. This was very noisy and dusty, and fairly hard work, but good fun.

Crushed rocks before being milled

The ground up rock was then sieved, and we retained the 250-500µm size fraction, keeping the rest in case we didn’t have enough quartz in these.

Crushed rock having been crushed and sieved. Note how different in mineral content the rock samples can be!

The final step for this week in the labs was using the Frantz machine.  A hopper slowly releases the grains of crushed rock onto a track which vibrates past a very strong electro-magnet.  Any magnetically charged particles are attracted to this and taken down a separate track, into a separate container.  The non-magnetic particles (such as quartz), aren’t attracted, and take a separate route (see video below).

So, I’ve now left my samples there with the lab staff for a series of etches with hydrofluoric and nitric acid.  I’m heading back in about a month to finish the samples off and then run them on the mass spectrometer.  Hopefully then it will spit out some nice dates which I can use to develop a deglacial chronology for the northern half of the Uummannaq Ice Stream System!

Rockfall at Franz Josef glacier

Glaciers transport material down-valley in a variety of different ways.  It can be carried in meltwater (glaciofluvial), entrained and dragged along the base of a glacier (subglacial), buried within the ice (englacial), or carried on the glacier surface (supraglacial).

Of course these processes vary both spatially and temporally, a single rock or grain of sand may experience all of these transport mechanisms during its journey from the top of a mountain to a glacier foreland.  For example, a rock may fall onto the surface of the ice and be carried supraglacially, before being buried and becoming englacial, brought to the base of a glacier and transported subglacially, and finally melting out and transported down valley glaciofluvially.

Supraglacial material is derived from mass movement events on free face valley walls or nunataks adjacent to the glacier. The video at the top of this post shows one such event on the Franz Josef glacier, South Island, New Zealand. This was captured on video by a lucky (no one was hurt) tour party that visited the glacier that day.

Debris covered glaciers have a lower albedo than clean-ice glaciers.  This insulating debris layer means ablation is lower; therefore debris-covered glaciers are less sensitive to climatic change.  It has been hypothesised a rockfall event at the Franz Josef glacier ~13,000 years ago caused a non-climatic glacial advance, responsible for depositing a large terminal moraine, named the Waiho Loop, 14km downvalley of the current glacier terminus.

This theory originated when it was found that a lot of the Waiho Loop moraine was made of supraglacial debris.  Supraglacial debris is typically very angular (see the rock the tour guide is holding at 1 min 40 seconds), as it has undergone very little active transport, compared to debris that is rounded at the base of a glacier .

This is a controversial theory, as it proposes that the moraine represents a non-climatic glacier signal.  However, many glaciologists still believe that the Waiho Loop was deposited during glacier response to cooling events in the aftermath of deglaciation from the last glacial maximum.  However, current efforts to date the precise age of this advance, using radiocarbon and cosmogenic nuclides, suggest that the dynamics of the Franz Josef glacier were out of sync with other South Island glaciers and local climate at this time. There are many potential sources of error involved with these techniques, so the debate continues.  This is just one of many examples of equifinality we find in the natural world; where an end result can potentially be reached in many ways.  As Quaternary scientists, it’s our job to pick apart the causative mechanisms, and come to conclusions.Who knows, maybe this event will cause another glacial advance…

In the mean time, enjoy the video.

This video was found on The Landslides Blog. A story from the local paper can also be found here.

Any Questions? – with Tim Lane

This is the first of what we hope will become a regular feature, in which we interview someone working in the Quaternary Science field to find out what they do and what they like about doing it (and more importantly what they don’t). First up is the co-author of this blog Mr Timothy Lane, a PhD student at Durham University in the UK.

IQSB: Can you explain for our readers what you are researching?

TL:  Essentially I am trying to reconstruct the thickness, extent and behaviour of a large ice stream in central west Greenland, from about 20,000 years ago to the present day.  An ice stream is a fast flowing glacier, and about 20,000 years ago, during the last glaciation, the ice in Greenland was far more extensive.  We’re using a variety of methods to reconstruct this ice stream.  We look at the sediment and landscape it leaves behind so we can tell where the ice was, and in which direction it flowed, and we can use material from both lakes and rocks to try and constrain a date on when the ice retreated.

Hopefully this will help other scientists who are trying to look at the entire Greenland Ice Sheet, and reconstruct its behaviour.  It will also help to feed information into models of sea level change.

IQSB: Cool, got any good photos?

TL: Yeh!

There are more here from 2010:

Greenland

And here from 2011:

Greenland 2011

IQSB: What made you want to undertake a PhD?

TL: While I was doing my Masters at Royal Holloway and UCL, I realised that I loved research, and it was the only thing I really wanted to do in the future.  Funding is always an issue, and I was lucky enough to get a fair amount of funding.  I’ve had to scrape together money for the fieldtrips, but I count myself as lucky!  It took me a bit of time to decide I definitely wanted to go ahead with one, but I knew it was right, and loved the project.

IQSB: What have you found hardest about the process thus far?

TL: Hmm.  I’d say that the complete independence can be a curse as well as a blessing.  If you’re having a bad week, or get knocked back by negative feedback/results not working etc it can be hard to drag yourself back to get on with your work.  The trouble is that there’s no one else to tell you to do it, other than your supervisor.  Similarly, it can be a lonely experience.  I’m lucky in Durham as they have a strong postgraduate community, both through the department and Ustinov College (a sort of halls of residence with a bar and social/sports community attached).

IQSB: Can you describe a typical day?

TL: I guess it depends really.  I am normally in the office by about 8.45-9.00am, and if I have nothing else on will work at my computer all day (Split up by coffee breaks of course!)!  If I have lab work to do I will spend the day in the Geography department labs, or in the GIS room.  We also tutor undergraduates, and demonstrate on modules, so my day is often broken up with helping them.  Obviously when I’m on fieldwork it’s quite a different daily routine…..

IQSB: What are your plans for when you graduate?

TL:  I’m not entirely sure yet.  I’d love to stay in academia or research, but it’s a competitive field so we’ll see how it goes.  Ideally I’d like to work as a postdoctoral researcher overseas somewhere.  At the moment I’m thinking of Norway, Canada, America or New Zealand.  I like the idea of moving country to change scene, meet new people, and experience the ways research works in other institutions and countries.

IQSB: And finally, what is the coolest thing about being a glaciology PhD student at Durham University?

TL: Well Durham itself is a great town, small and beautiful.  The flexibility the PhD offers is another massive positive, and as long as you’re prepared to put the hard work in then the rewards are massive.  The best part of the PhD has got to be the fieldwork though.  Getting the chance to go to remote areas of Greenland as part of my “job” is incredible.  Spending a month camping in complete isolation with just two other people is a great experience, and the fact that we’re researching areas which have really never been studied before is very rewarding.  You see some incredible places that 99.9% of the world will never see, and have numerous experiences which you will remember for the rest of your life.

PhD the Movie: Piled Higher and Deeper

‘Piled Higher and Deeper’ brings to life the popular ‘PhD Comics’ series published by Jorge Cham, which satirises the journey of graduate students as they try to forge a career in academia.

The film itself follows the journey of two main characters from the comics: the young, fresh-faced, naive ‘Nameless hero’ (whose name is revealed at the end of the movie) striving to impress the infamous Professor Brian Smith; and Cecilia the grad student juggling TA responsibilities with her doctoral work.

The 67min film is divided into chapters that follow the typical structure of a academic thesis. In the ‘Introduction’ we see the nameless hero attending interviews at various prestigious universities as he battles other A-grade students and the busy schedules of potential supervisors to try to win a place in grad school. The rest of the film follows his progress as he is taken on by Professor Brian Smith as one of his ‘lab rats’, forced to work long hours with ancient equipment for little to no recognition. Mike Slackernerny is appointed as the hero’s mentor and throughout the film introduces him to some of the golden rules of graduate research, namely: stock up on free food at every opportunity; be prepared for all technical equipment to cease working when your supervisor comes within a 5m radius; and, never, NEVER, ask anyone how their research is going. The scene is also set for Cecilia who is coming towards the end of her doctoral work and is finding herself ‘waiting for someone to die’ so that a faculty position becomes available. She struggles to balance her teaching responsibilities, which include listening to undergraduate excuses for extension requests, and ensuring their grades fit a Gaussian distribution with a mean of 61.871 to her supervisors satisfaction.

Hats off to whoever was in charge of casting as the likeness of some of the actors to their graphic counterparts is uncanny! In particular Professor Brian Smith who comes complete with obligatory beard and really brings to life that insensitive glare from the other side of the desk. Mike Slackernerny’s hairdo is similarly well cast. One continuity issue that I noticed was the nameless hero’s haircut – it seemed to differ in every scene. I’m not sure if this was purposeful in order to represent the passing of significant amounts of time or is just representative of the order in which the scenes were filmed, but it certainly stood out.

One question that I left the screening with, is how much actual PhD students identify and agree with the stereotypes portrayed in both comic and movie. Speaking to people after the screening, all of them admitted while they could relate to small things like being poorly paid and pulling  the occasional all-nighter, the majority actually have very good relationships with their supervisors and thoroughly enjoy their research.

This is something that stood out to me long before this film came out. When I learned that I had got scholarship for my PhD I immediately began reading postgraduate blogs and advice online and was struck by the severe lack of anyone saying how much they enjoyed their time spent doing doctoral research. I know people who have bad experiences are more likely to vocalise them, but for any undergraduates keen to continue in academia, a quick Google search of ‘life as a PhD student’ will soon have them filling out industry job applications. Perhaps Jorge Cham could produce the odd comic strip that portrays the joy of winning a research grant for example, or at least postgrad bloggers could be a bit more vocal about such things, no?

Overall, the film is very enjoyable with many laugh out loud moments – usually those taken straight from the original comic strips and is probably best enjoyed in the company of other grad students, while enjoying some free pizza (thanks Postgraduate Student Assoc!). Using the Powers Roundness rating scheme I’ll award this film a rating of Sub-Rounded.

Anyone else seen it? Let us know what you think below…

Greenland – The Times Atlas vs Scientists

There has been a big furore over the past few weeks regarding the publication of the new, 13th Edition of the Times Comprehensive Atlas of the World.  Specifically, the depiction of the Greenland Ice Sheet (GIS), and the associated press release, which said that the GIS had lost 15% of its permanent ice cover.

Different in the permanent ice cover in Greenland between 1999 (left) and 2011 (right)

This figure is a gross over-exagerration (Greenland has actually lost about 0.1% over the last decade), and was picked up by a number of scientists almost immediately.  Emails were being fired around mailing lists rapidly, as glaciologists attempted to find the best way to remove this figure from the mass media, before it became public knowledge and damaged the reputation of glaciologists working in Greenland (of which there are a lot).  The Times Atlas publishers (Harper Collins) initially refuted the claims, saying  that they:

“are the best there is … Our data shows that it has reduced by 15%. That’s categorical.”

Initially it was unclear where the “15%” figure had appeared from, but it soon emerged that the new map bared a striking resemblance to an online map of the GIS on the National Snow and Ice Data Centre’s website.  Those working on Greenland for the Times Atlas had clearly misinterpreted this map, and taken it to be an absolute measure of all ice cover in Greenland, when it actually represented something else.

The reason that this cartographer’s error spiralled out of control is simple – scientists were not consulted.  Had consultation taken place, the error on the map, and the consequent ice loss figure of 15% would have been immediately spotted and corrected.  The error, if left uncorrected would have discredited what a number of scientists from institutions across American and Europe have been working on for a number of years.  The actual picture of what is happening to the GIS is extremely complex, and remains poorly understood in areas.  It is a story of variability, with extreme thinning and increased in melting in areas, counterpoised with slight thickening in other areas.

The details are too complex to do justice in this post, but maybe another time….

The main issue that arose from this “crisis” was not the actual error made by the cartographers, this was relatively easily rectified in the end, but the ease at which this information got into the public domain with no input from scientific experts.  Such experts, who have built their career working on monitoring changes of the GIS, are subject to the rigorous peer-review system when disseminating their work to the wider scientific community. The problem with this however, is that this information is largely only available to the academic community, whose institutions provide paid subscriptions to the content. ‘Scientific’ information reaching the public through popular media is subject to no such scrutiny and due to the far greater reach of such outlets, errors can propagate much further much more quickly. With recent “fiascos” tarnishing science’s reputation (Climategate, the IPCC), science needs all the help it can get to stay favouring in the public’s eyes.  Thankfully this episode was resolved quickly, and if anything, demonstrated the ability of scientists to quash rumours with scientific evidence quickly.

At no point did the writers think to contact any scientists over the alarmingly large 15% ice loss Greenland had experienced.  Instead they simply put it to print and made a fool of themselves as a result.  They have now agreed to work with scientists in the future to correct this issue, and ensure it doesn’t happen again.

Hopefully this will be the standard position for those publishing material that should (and does) have a grounding in scientific work.

For an interesting alternative visualisation of melting in Greenland visit Cryocity.