Archive Science

The Galápagos of the Southern Ocean – Part II: Enderby Island Matthew Wood Apr 06

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Greetings, Scibloggers! Before I begin I should explain my very long hiatus in posting to Sciblogs.

In early 2010 I started Journeys to the Ice, an audio podcast and blog on Antarctic science usually featuring recent research from the Antarctic Research Centre at Victoria University of Wellington. Late that year I travelled to the sub-Antarctic islands of New Zealand and Australia and in early 2011 I started a vidcast series based on that trip. Shortly after completing part 1 however, I found myself back in the world of field-based exploration geology, initially on the West Coast, then hunting rare earths in Mozambique during 2012 followed by adventures in Ghana last year.

Now that I’m back in Wellington it seems high time that I continue with the sub-Antarctic mini documentaries. Overhauling my editing suite to Final Cut Pro X has taken time, but ultimately has led to faster, more reliable editing in my opinion. The 10.0 release of that program was widely denounced by professionals, but has since had major updates returning many missing features.

It’s exciting to be returning to the world of science media. Keep an eye out for more episodes of The Galápagos of the Southern Ocean in the coming months.


Our first port of call is Enderby Island at the northern end of the Auckland Islands group. 2014 marks the twentieth anniversary of the eradication of introduced land mammals on the island. The subsequent return of many endangered species (several of which are endemic to the island group) has been hailed as a conservation success story. Megaherbs flourish on the island once more. Some of the more conspicuous denizens of Enderby that we encounter are the Yellow-eyed Penguin and the New Zealand Sea Lion.

New Zealand Sea Lion

To download the vidcast for your Apple device, simply subscribe for free through the iTunes Store on your computer or through the Podcasts app for iOS. For playback on other portable media devices please download from the Journeys to the Ice homepage. Otherwise you can watch it straight away via YouTube in the window below. YouTube video looks and sounds best in 720p.

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Photo (c) 2010 Matthew Wood

The Galápagos of the Southern Ocean – Part I: Bon Voyage Matthew Wood Feb 17


The Galápagos of the Southern Ocean is an adventure tourism cruise to the sub-Antarctic islands of New Zeland and Australia run by Christchurch-based Heritage Expeditions. The rich and diverse wildlife of the region is driven by high primary productivity at these latitudes due to upwelling along major ocean fronts. The human history of the islands is one of discovery, environmental degradation and more recently, restoration and conservation. The Enderby Trust provides financial support for young adults to experience the the natural environment of the Southern Ocean and Antarctica on board Heritage Expeditions’ polar research vessel, Spirit of Enderby.


The vidcast is optimised for playback on iPhone 4 and 4th Generation iPod Touch. To download the vidcast for your Apple device, simply search and subscribe for free through the iTunes Store. For playback on other portable media devices please download from the Journeys to the Ice homepage. Otherwise you can watch it straight away via YouTube in the window below. YouTube video looks and sounds best in 720p.

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Photo (c) 2010 Jessica Kerr

Climate Change and New Zealand’s Future Matthew Wood Feb 02

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ESCI 201: Climate Change and New Zealand’s Future is a Victoria University summer course which draws on the knowledge of many of Wellington’s preeminent experts in the realm of climate change. Much like the structure of the IPCC Assessment Reports, the course begins by examining the scientific basis of climate change and then explores the implications for human societies and the various options for mitigation. Most of the guest lecturers gathered at Rutherford House on Friday for a public panel discussion that brought the three-week course to a close.

Jonathan Boston_Peter BarrettProfessor Jonathan Boston (Director, Institute of Policy Studies, VUW) and Professor Peter Barrett (Climate Change Research Institute, VUW)

A political and social challenge

The discussion began by focusing on climate change as a challenge for society. As Dr David Wratt, Chief Climate Scientist at NIWA, pointed out, climate change is an unprecedented political challenge demanding both long-term future thinking and a unified global response. Dr Adrian Macey, UNFCCC Kyoto Protocol Chair, noted that existing infrastructural inertia poses a significant barrier to change: a new coal-powered power plant, for example, would have a design life of many decades. However, Macey also suggested that the slow societal response to climate change needs to be put in perspective by considering the equal (or even greater) lack of progress on other issues, such as international disarmament. He went on to mention that climate change is, of course, only part of a larger matrix of interconnected global problems, including the often-ignored issue of population growth.

So with climate change being as complex an issue as it is, combined with the deliberate and unwarranted attacks on climate change science either side of the political failure at Copenhagen, perhaps it is not surprising that so little has been achieved. Professor Peter Barrett of the VUW Climate Change Research Institute highly recommended the 2010 book Merchants of Doubt, by Naomi Oreskes and Erik M Conway, which compares contrarianism in the climate change debate with now-discounted stances in earlier controversies like that over the adverse health effects of tobacco smoking. This led on to a suggestion from the audience that perhaps the key to unlocking the climate change dilemma lies in human psychology: a discipline conspicuously unrepresented in the panel (but one which will almost certainly be represented in future iterations of this course). New research suggests that people are more likely to lean towards climate change denial if the science is presented with a negative focus (ie emphasising the dire consequences of inaction). Could emerging insights from psychology and the social sciences lead to a significant change in climate change messaging?

Kevin Cudby_David WrattKevin Cudby (Author, From Smoke to Mirrors) and Dr David Wratt (Chief Climate Scientist, NIWA)

Getting the message out there

The effectiveness of science communication was another hot topic of discussion. Concepts integral to climate change, such as probability, uncertainty, variability and risk, make climate change fundamentally difficult to communicate to a non-scientific audience. Dacia Herbulock of the Science Media Centre raised the point that it is easy to say something spurious in the 30 second window of the news soundbite (often referring to conveniently ‘cherry picked’ studies), but to set the record straight scientifically may take 30 minutes or more: an obvious dilemma for well-informed science communication. Judy Lawrence, Senior Associate at the VUW Climate Change Research Institute, suggested that instead of trying to fashion the climate change message for distribution in mainstream media, a more effective alternative might be to target specific audiences (industry, local government etc) with tailor-made, policy-relevant messages.

How, then, should scientists engage with the public? Professor Jonathan Boston, Director of the Victoria University Institute of Policy Studies, said that “we live in a context where we have to trust people to do their jobs well”. Barrett agreed that scientists should not have to justify themselves to skeptical non-scientists: we trust medical doctors to do their jobs well, why should climate scientists be treated any differently?  Dr James Renwick (Principal Climate Scientist at NIWA) said that he understood why non-scientists feel that climate is something on which they can have an opinion: people KNOW the weather, it affects their everyday lives. However, this is of course the classic problem of confusing the weather with climate.

Dr Lionel Carter (ARC) pointed out that since the ‘Climategate’ hacked emails saga it was understandable that scientists have become somewhat “gun shy”, suggesting that the best option was to stick to the facts and observations rather than getting involved in polarised public debates. Herbulock observed, by contrast, that “there has to be some degree of strategy” and collective thinking among climate change scientists: we need to go beyond the media and invest in educational programs, especially for young people. She also identified the important role for non-scientist communicators and responsible journalism, with Barrett pointing to the ongoing work of Gareth Renowden and Gareth Morgan.  Renwick suggested that perhaps climate change science has simply not been compelling enough. Wratt followed by saying he once believed that if scientists were compelling enough the world would change, but has since realised that the issue is much more complicated than that. It seems that success on the climate change communication front will require an orchestrated effort by scientists and non-scientists alike.

Dacia Herbulock_James Renwick_Lionel CarterDacia Herbulock (Science Media Centre), Dr James Renwick (NIWA) and Dr Lionel Carter (ARC)

Where is the leadership?

Questioning from the audience raised the point that in New Zealand there is currently little government-prescribed impetus for the private sector to join the climate change mitigation effort.  Carter pointed out that at an international level, some leadership is actually coming from the private sector rather than governments, refering to BHP Billiton’s recent (presumably financially-driven) foray into carbon credit trading. Dr Martin Manning, Director of the Climate Change Research Institute, agreed that “the private sector is moving in and taking a strong line on climate change”, irrespective of the actions of governments, alluding to the recent actions of Deutsche Bank and the wider international reinsurance industry. Macey added that while the ideal of global ‘Green Growth‘ will not be on the horizon any time soon, significant investments in renewable energy technologies in China and Korea are setting a good example in the meantime. As Carter suggested, this will also have implications for the public perception of the climate change debate: “if industry is taking notice of this, there must be something in it”.

How could governments be doing better? Macey believes there is a need for increased support for research and development and better emissions accounting systems, especially in New Zealand where agricultural methane is the primary emissions source.  Dr Howard Larsen of the VUW Institute of Policy Studies clarified that atmospheric methane from New Zealand agriculture is short-lived (~one decade) and so with no growth in agriculture there is no long-lasting irreversible climate forcing, unlike with carbon dioxide emissions.  However, as Boston mentioned, if we classify food as exempt from emissions regulation, where do we draw the line? Food production? Food transport? Retailing and consumption? Fossil fuels are inherent to all stages of food production, even here in ‘clean green’ New Zealand. Kevin Cudby added that, as an exporting nation, our emissions are often on others’ behalves: with food exports, who should pay the emissions price? The producer or consumer?

These are all questions that will need to be addressed when creating new domestic climate change mitigation policy. Cudby is not convinced that any specific carbon pricing scheme will work and instead advocates that we should simply “turn the tap off” and ban fossil fuels outright in New Zealand. This resetting of the energy paradigm could be achieved over a transition period of several decades as outlined in detail in his recent book, From Smoke to Mirrors. Barrett noted that similar sentiments are expressed in Dr James Hansen’s recent book, Storms of My Grandchildren.


The panel touched on some intriguing issues, but obviously the discussion could have continued for much longer if time had allowed. Fortunately the Climate Change Research Institute will be exploring these issues and more in the Climate Futures: Pathways for Society forum at Te Papa over 31st March — 1st April 2011. The conference will include sessions on climate change psychology and communication. Many thanks to all the guest lecturers for their contribution to the ESCI 201 course. Also, no course is possible without the enthusiasm and hard work of its students, so cheers guys. Well done on your posters and good luck for your essays!

The students of ESCI 201: Climate Change and New Zealand’s Future were fortunate to receive additional guest lectures and tutorials by:

  • Dr Katja Riedel – NIWA
  • Dr John Collen – School of Geography, Environment and Earth Science, VUW
  • Peter Griffin – Science Media Centre
  • Caleb Royle – Raukawa Marae
  • Pataka Moore – Raukawa Marae
  • Dr Nancy Bertler – ARC and GNS Science (original course coordinator)
  • Dr Dan Zwartz – ARC (current course coordinator)

The Greenland Ice Sheet in a high-CO2 world Matthew Wood Jan 06

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Before I introduce the latest instalment of the podcast, I’d like to take the opportunity to say a big hello and happy new year to everyone in the Sciblogs community. I hope you all enjoyed the festive season and that 2011 brings with it plenty of exciting science stories. I should also explain my absence towards the end of last year: my girlfriend and I had the good fortune to be co-recipients of Enderby scholarships (which I posted on early last year) and so we were whisked away at the last minute for an adventure in the sub-Antarctic islands. Keep an eye out for my series of vidcasts on the Galapagos of the Southern Ocean cruise over the next few months. But now to the task at hand…


In June last year I interviewed Dr. Andrew Mackintosh, who leads the Climate Models group of ANZICE, about the cutting-edge glacial modeling work being carried out by the Antarctic Research Centre at Victoria University of Wellington. 12,000 km across the Pacific Ocean, the Climate Modeling Group at the University of Victoria in British Columbia is hard at work on similar research. Bridging the watery gap between these two Victorias is the work of a young modeler called Jeremy Fyke.

In his PhD research, Jeremy is simulating climate / ice sheet interactions for Greenland using a coupled climate and ice sheet computer model (UVic Earth System Climate Model). In ‘equilibrium simulations’ the model can be forced with various fixed atmospheric carbon dioxide concentrations, usually defined as multiples of the preindustrial CO2 level (~280 ppm by volume). For any given atmospheric CO2 concentration, the ice sheet can have multiple steady states, depending on the initial ice sheet conditions (i.e. full preindustrial ice extent, depleted ice or ice-free). So an existing ice sheet might change to a stable, but diminished state under elevated CO2, but an ice-free Greenland would not be able to grow a similarly sized ice sheet from scratch in an identical atmosphere: the resulting ice sheet could be very small or non-existent. This highlights the importance of feedbacks in the climate / ice sheet system: an existing ice sheet has a size, shape and surface character (e.g. albedo) that can begin to dictate its own climate setting, which is generally favorable to its continued growth or stability. Jeremy’s work has shown that the Greenland Ice Sheet has been self-sustaining throughout the Holocene.

Jeremy Fyke Greenland Ice Sheet

The other main aspect of Jeremy’s work has been modeling the deglaciation of Greenland under transient emissions scenarios, starting from a stable preindustrial state. There appears to be a threshold for a large-scale collapse (>75%  ice loss) of the Greenland Ice Sheet at around three to four times preindustrial CO2. Interestingly, though, the transient scenarios do allow for a temporary exceeding of this threshold due to the long response time of the ice sheet in Jeremy’s model (good news for a society that is unlikely to change its habits overnight). The slow response of the simulated ice sheet is thought to be related to the model’s low polar amplification of global climate signals. However, even with what are likely to be conservatively low estimates of ice sheet change, the model suggests that at around five times preindustrial atmospheric CO2 there would be no remaining ice on Greenland. That equates to ~7 m of global sea level rise. Forced by an atmosphere that currently has 1.4 times the background Quaternary interglacial CO2 concentration, the Greenland Ice Sheet is already showing signs of deglaciation, and anthropogenic greenhouse gas emissions are likely to inhibit the natural inception of future North American ice sheets.

Jeremy’s research is also shedding new light on the little-known long-term glacial history of the Greenland Ice Sheet. Records of ice-rafted debris in the North Atlantic have been interpreted as evidence for a continental-scale ice sheet as far back as the Oligocene or even Eocene. However, Jeremy’s results show that even a small localised ice cap centered on the mountains of Greenland’s southeast coast would be able to coalesce at four times preindustrial CO2 and discharge ice to sea level. This suggests that the expansive ice sheet that we see today could be a much more recent addition to the cryosphere than some have previously thought.


Modeling of this kind is very computationally expensive. Each simulation in this study typically requires a month of non-stop computer processing time. With around 60 ‘runs’ in total, Jeremy’s study has had the CPU working steadily for around four years now, with more runs waiting in the queue. Yet models exist that are orders of magnitude more complex still, such as many of those utilised by IPCC forecasters. With greater processing power comes the ability to run scenarios at increasingly fine temporal and spatial resolutions and therefore (hopefully) to replicate the ‘real world’ systems more accurately. It is important, therefore, to bear in mind that Jeremy’s work is subject to the limitations inherent to modeling and that the results are highly model-specific. Comparing the results of different models is however an important scientific opportunity in itself: cross-examination between modeling studies can help sort those results that are merely artifacts of particular model physics from those that are systemic in the real world.

The history and future of the Greenland Ice Sheet remain shrouded in uncertainty, but by seeking to understand the climate / ice sheet system at a fundamental level, modelers like Jeremy are now able to simulate past glacial fluctuations and explore the potential range of future ice sheet configurations. Whether the future of the Greenland Ice Sheet is defined by regained stability, partial deglaciation and regrowth, or large-scale deglaciation is really up to us: will we be able to wean ourselves off fossil fuels in time?

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Figure modified from Fyke et al (in prep). Satellite image (c) 2010 Google Earth. This research was made possible by the supervision of Dr. Andrew J. Weaver (School of Earth and Ocean Sciences, University of Victoria), Dr. Andrew Mackintosh (ARC) and Dr. Lionel Carter (ARC).

New Zealand Palynology: Into the West Matthew Wood Nov 10


PlagianthusThe land is fickle. Uplift and denudation can make paleoclimate science on land difficult in some cases and impossible in others. Oh, to think of all the beautiful terrestrial climate records that have been lost to the sands (or silts or clays) of time! Much more reliable is the ocean, where change is measured not in years or decades, but millenia.

In central Westland, the pollen and spores of terrestrial plants find their way out to sea in the suspended sediment of rivers and their marine counterparts, submarine canyons (think giant underwater rivers snaking their way down the steep continental slope). At one point on the true right levee of the Hokitika Canyon, 3.2 metres of sediment (including entombed pollen and marine microfossils) has slowly and steadily accumulated over the past 210,000 years. Collected by NIWA’s RV Tangaroa in 2005, this record became the basis the longest paleovegetation record for Westland to date.

Palynomorph Sedimentation Model

The MSc study, recently completed by Matt Ryan at the ARC, documented central Westland vegetation succession throughout the last two glacial cycles. By counting the proportions of various pollen taxa in samples taken down the full length of the core, a picture emerged of changing land vegetation over time. However, relating these changes to known climatic events required definitive age control.

δ18O or ‘delta-O-18′ is a measure of the ratio between the stable isotopes of oxygen (18O:16O). This ratio in the shells of benthic foraminifera is an indirect proxy for global ice volume: evaporation preferentially removes the lighter isotope, 16O from the ocean, so when the resulting precipitation falls in the form of snow on an ice sheet, the ocean is left enriched in oxygen’s heavier isotope, 18O.  Since this proxy measures a global signal, new records can be confidently tied to existing, independently dated oxygen isotope curves. A δ18O curve was generated for this core from the benthic foram species, Globigerina bulliodes, and was tied to the global benthic isotope stack of Lisiecki and Raymo (2005).

TAN0513-14 Pollen Record

By comparing the vegetation story to sea surface temperature records, Matt was able to see which tree species colonised the post-glacial valleys of Westland first, replacing the herb and shrub taxa characteristic of ice ages. While many podocarp/hardwood species respond immediately to interglacial warming on the West Coast, a re-dated pollen record from off the coast of South Canterbury shows that there is a significant delay in vegetation response to the east of the South Island’s main divide. Also, the ‘beech-gap’, a mysterious present day absence of southern beech forest across central Westland, is explained in terms of out-competing by tall tree taxa during the last deglaciation.

The large scope and workload of this Master’s project has been good practice for Matt, who is about to embark on a PhD in which he will once again greatly extend the paleovegetation record of Westland, this time as far back as the intriguing warm interglacial and Holocene analogue, Marine Isotope Stage 11. Good on ya Matt and all the best!

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Figures by Matt Ryan. Turbidity flow schematic modified from Peakall et al. (2000). Hokitika Canyon multibeam bathymetry data courtesy of NIWA. This research was made possible by the supervision of Dr. Gavin Dunbar and Dr. Michael Hannah.

New Zealand Palynology: Look to the East Matthew Wood Nov 02

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When you take a sample of sediment from the seafloor and remove all the carbonate and silica — nearly the whole sample in most cases — what are you left with?

Palynomorphs are organic microfossils that include the pollen and spores of terrestrial plants, the cellulose remains of marine phytoplankton called dinoflagellates, and other particulate organic matter. Palynology is an important part of the Antarctic Research Centre’s paleoclimate research because unlike other climate proxies, palynology allows the direct comparison between contemporaneous terrestrial (land plant succession) and marine (dinoflagellate cyst) records.

Joe Prebble recently returned to the Antarctic Research Centre to undertake a PhD project in palynology. He’s interested in quantitatively reconstructing environmental conditions of the New Zealand region during Marine Isotope Stage 11, a particularly warm and stable Pleistocene interglacial that is a good analogue for projected global temperatures of the near future. As Joe points out, the analogue falls short when considering atmospheric greenhouse gas levels: we have already gone well beyond the natural upper limit of atmospheric carbon dioxide variability during the Quaternary. By studying dinoflagellate cyst assemblages of modern seafloor sediment sample locations, and relating them to corresponding quantified ocean conditions (such as sea surface temperature), Joe will be able to generate a ‘cyst-based transfer function’ — effectively turning fossil cyst assemblages, from well-dated sediment cores, into paleo-thermometers.


A sediment trap program run by Dr. Scott Nodder, a marine geologist at NIWA, is helping to define the seasonality of ocean productivity (including dinoflagellates) in this region. Traps have been positioned to the north and south of the Chatham Rise (and the associated, overlying Subtropical Front) for the past decade. Time series data from this program will help in finding out exactly what time of the year dinoflagellates shed their cysts, allowing a more precise tie between modern cyst assemblages and empirical environmental data (variously sourced from the World Ocean Atlas and remote sensing satellites such as MODIS and SeaWIFS).

As previously reported, in late 2009 the Integrated Ocean Drilling Program research vessel JOIDES Resolution collected a record-breaking 1928 m sediment core from off the Canterbury Coast (Site 1352B). The core’s shore-proximal, continental shelf location makes it near-perfect for palynological research, with: a high sedimentation rate (thus a high resolution record); rapid transport and deposition of large amounts of terrestrial pollen and spores; and a high local production of neritic dinoflagellate cysts. However, the Subtropical Front off eastern New Zealand is effectively locked in place throughout glacial cycles by the bathymetry of the Chatham Rise, whereas in other ocean basins the front may migrate by up to four or five degrees of latitude. Therefore interpreting ocean conditions close to the South Island’s east coast can be difficult. The cyst record from Site 594 may help provide a clearer picture of local oceanographic changes at these timescales.


For the transfer function to be reliable it needs to be shown that the modern seafloor cyst assemblages are truly representative of the overlying water column, i.e. that there has been no significant lateral transport or reworking. This will be one of the main challenges of the research, but if this assumption is demonstrated to be correct, Joe’s transfer function will be a hugely valuable addition to paleoclimate science in New Zealand.

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Photo (c) 2005 Matthew Wood

Marsden grant takes microbiology to the extreme Matthew Wood Sep 27

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Dr. Charles Lee is a FRST Postdoctoral Research Fellow at the Department of Biological Sciences at The University of Waikato. His research into the microbial ecology of extreme environments received a significant financial boost on Friday when the 2010 Marsden Fund grants were announced. The Fast-Start grant will support new research into the relationship between the McMurdo Dry Valleys soils and their resident microbial populations. Studying the microscopic life of this frozen desert could shed new light on the long-term glacial history of the valleys, while providing a valuable biological perspective with which to assess current and future environmental change in the Antarctic. Dr. Lee was kind enough to field a few questions from Journeys to the Ice

The McMurdo Dry Valleys, deep sea hydrothermal vents… It sounds like you have a penchant for extreme environments!?

I think it’s mostly a matter of being at the right place at the right time (and being funded at the right time helps, too). Working on extreme environments has its obviously perks (i.e., extreme tourism), but it also comes with a lot of unique challenges. These challenges, both in terms of the fieldwork and lab analyses, are as much of a draw as the excitement and experiences for me, and applying a lot of cutting-edge molecular and bioinformatic tools to these unique habitats has allowed us to answer many longstanding questions, which is of course very satisfying.

What kind of bioinformatic tools do you use in your research?

A lot of our research is based on metagenomic and metatranscriptomic sequencing, and that undoubtedly is the most challenging part when it comes to bioinformatics. Pyrosequencing of PCR amplicons is quickly becoming the most common analysis for studying microbial community structure, and we have made some very significant progress in characterizing and validating this technique through both benchwork and bioinformatic analyses. We’re also interested in analyzing molecular biology data using stringent statistical algorithms and resolving the relationship between biological and abiotic (i.e., geochemistry) data.

Charles Lee

What interests you about the genetics of microscopic life, rather than that of larger organisms?

I tend to look at the components of an ecosystem in terms of total biomass, and if one looks at things that way, it would be foolish not to understand the structure and function of microbial communities as part of studying an ecosystem. This is particularly true in extreme environments such as deep-sea hydrothermal vents, where the entire ecosystem literally relies on the bacteria to harvest energy from the environment. The microbiota of the Antarctic Dry Valleys is interesting in a different way since it is one of the few places on Earth where bacterial and archaeal communities are not heavily influenced by more complex organisms, allowing us to examine how physicochemical factors influence microbial communities.

You also study the geochemical transfers between microbial communities and their environments: do you see yourself as being just as much an Earth scientist as a biologist?

It is very true that I’m becoming more and more of an Earth scientist. Before I started doing Antarctic research I couldn’t tell granite from marble, but identifying geological features has now become an obsession of mine. As I said earlier, the Dry Valleys is one of the few places on Earth where the physical environment and geochemistry predominantly determine the structure and function of microbial communities, so it would be negligent of me to not have some basic understandings of geology.

To use the living biology of an environment to make inferences about the longer term evolution of that environment seems to be a fairly novel approach. In what ways might microbial genetics and geochemistry give you insights into the glacial history of the McMurdo Dry Valleys?

People have long assumed that the microbial ecology of the Dry Valleys is influenced or even determined by ancient organic material, which of course is determined by the glacial history of the location. There’s some evidence that the first part of this statement is not necessarily true, but glacial history is also manifested in a variety of other physicochemical conditions that do influence microbial communities. People have tried to identify such links with more complex organisms such as lichen or micro-invertebrates, but so far nothing solid has been accepted by the wider community. Identifying the connection between microbial ecology and glacial geomorphology is the more risky part of my proposed research, but the potential reward is great. My current hypothesis is that the “rare biosphere” of local microbial communities, which can only be described economically using PCR amplicon pyrosequencing, contains some information on the glacial history.

Lake Vida

Is it likely that the microscopic life of the Dry Valleys is, or soon will be, influenced by anthropogenic climate change?

Anthropogenic climate change will have a greater effect on polar ecosystems than temperate ones due to the fact that even relatively minor changes can lead to phase shift (i.e., ice to water) in the polar regions. The question right now is how quickly will Dry Valley biota respond to climate change, given the cold temperatures and supposedly slow metabolism. We have some very fresh data that shows microbial communities can in fact respond to changes in climatic conditions very rapidly and drastically, which can have catastrophic consequences for the ecosystem.

Do you think the existence of life in such extreme terrestrial environments has implications for the possibility of life elsewhere in the solar system?

NASA has long used the Dry Valleys as an analog for Mars, and many people in the astrobiology community think the type of life found in the Dry Valleys is reflective of the type of life we can find on Mars. My personal view is that the current conditions on other planets may not matter as much as conditions in the past. Working in extreme environments has taught me to never underestimate the resilience of life, but for self-reproducing organisms to emerge from the primordial soup requires some fairly stringent conditions, so I think we may not necessarily be looking in the right places or using the right approaches right now.

Many thanks to Dr. Lee and congratulations to all the recipients of Marsden funding for 2010.


Top — (c) 2010 Charles Lee

Bottom — Lake Vida, Victoria Valley (c) 2003 Matthew Wood


Bonus Video Podcast: The Perito Moreno Glacier Rupture Cycle

The Perito Moreno Glacier is a major tourism drawcard for Argentine Patagonia. Its persistent advance during the 20th century has resulted in a dam and rupture cycle at its terminus in the formerly-glaciated upper reaches of Lago Argentino. The glacier is somewhat of an enigma: nearly all of the other Southern Patagonian Ice Field outlet glaciers are currently receding.

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The Snows of Ruapehu Matthew Wood Sep 13

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Mount Ruapehu could be viewed as New Zealand’s Kilimanjaro: the upper slopes of its formidable volcanic mass tower above the plain below, hosting glaciers that, considering the surrounding desert climes, have only the most tenuous claim to existence. As is the case with its Tanzanian counterpart — vividly documented in the 2006’s An Inconvenient Truth — Ruapehu’s glaciers have diminished considerably during historical times.

Ruapehu DEM aerial photo drape

The 20th Century recession of glaciers around the world has been one of the most ubiquitous and manifest signs of global warming to date. Previously we’ve seen how Antarctic Research Centre scientists have demonstrated this trend in the temperate glaciers of the New Zealand Southern Alps, albeit with anomalous, climate-driven advances of certain glaciers since the early 1980s. The ARC also has a keen scientific interest in the only remaining glaciers of the North Island.

Ruapehu owes much of its misshapen form to the erosive influence of glaciers, which, during glacial periods, were dramatically expanded. Today, the mountain’s small residual glaciers are pale shadows of their former glory, and precariously cling to the rough andesitic slopes at the very climatic, latitudinal and topographic limits for permanent ice in New Zealand.

Tom Paulin undertook a Master’s project on the Whangaehu Glacier (Ruapehu’s largest) after learning that there had been no major publications on North Island glaciers since 1988, no mass balance studies of this specific glacier had ever been conducted and — as a true sign of the times and trends — the only other similar study to have been conducted on Ruapehu was of a glacier that no longer existed. From 1954 to 1955, the Whakapapa Glacier experienced a 94 m retreat and 10-15 m of vertical downwasting, which led to the exposure of a bedrock ridge, effectively splitting the glacier in two and thus forming the Whakapapaiti and Whakapapanui glaciers. Ironically, it is the Whakapapaiti (‘iti’ meaning ‘small’ in Maori) that has survived: the Whakapapanui (‘big’) has lost so much mass that it is now merely a stagnant ice patch. Glaciers now remain only on the southern and eastern flanks of the mountain where they are relatively shielded from the sun.

A glacier’s end-of-summer snowline (EOSS) is commonly used in glaciology to quickly indicate the equilibrium line altitude (ELA): the elevation on a glacier surface at which accumulation is equal to mass loss via ablation (sublimation and/or melting). By documenting EOSSs in oblique aerial photos of the Whangaehu Glacier taken in over a 19 year period,  Tom was able to get a qualitative sense of the glacier’s mass balance shifts during this time. The inter-annual trends documented by this study were corroborated by snow accumulation data at Whakapapa Skifield, a direct record of the interplay between temperature and precipitation.

Whakapapa snow record

A quantitative mass balance study was also conducted. Between 2005 and 2007 direct measurements of snow accumulation were achieved by digging pits (up to six metres deep) into the glacier’s residual snow cover, reaching a hard, debris-rich layer that marks the beginning of any given ‘balance year’ of snow accumulation. Measuring the density of snow down the profile allows the calculation of water equivalent precipitation. The largest accumulation directly measured was 2988 mm (water equivalent) as averaged across the glacier surface.

A hot water drill was used to install 15 four metre plastic stakes into the centre-line of the glacier and the adjoining summit plateau. These served a double purpose: to measure ablation rates over time, and, with careful differential GPS monitoring (±0.5 m accuracy), to assess flow patterns of the ice. Many of the stakes required re-drilling during the study due to rapid ablation rates resulting in their near-complete exhumation. During the field study it was shown that the summit plateau and the Whangaehu are in fact completely separate systems: in the modern setting the summit plateau is a down-wasting ablation zone flowing to the northwest, while Whangaehu ice velocities are perpendicular, in the range of 10-38 m/year to the southeast.

Ice velocities

While snow does accumulate temporarily at the summit, it is blown away by strong winds before the end of the balance year and acts as an important source for snow accumulating on the Whangaehu Glacier. This means that the Whangaehu has an additional, ‘false’ ELA in its uppermost reaches, with its main accumulation zone being on the sheltered mid-slopes (as shown by data from the 2006 balance year at least).

Mass balance Whangaehu

The stake and snow pit data from a single year are combined to calculate the net mass balance of the glacier. Results show that the slightly negative 2006 balance year was followed by positive mass balance in 2007, in part related to a 48% increase in precipitation. In the longer term however, mass balance is not strongly associated with winter precipitation and is instead dictated mainly by summer temperatures and the length of the ablation season as measured in positive degree days.

Relating the observed changes in mass balance to local climate required the installation of New Zealand’s highest automatic climate station at Dome shelter. This climate station measures high-resolution records of air temperature, humidity, incoming solar radiation, and wind direction and speed. Meteorological data collection at such elevations is plagued with problems: the build up of thick rime ice deposits around equipment; wind speed gauges regularly ‘maxing out’; and atmospheric temperature inversions all pose significant challenges to attaining usable information. By comparing temperature data from the new station to the long-running weather station at Chateau Tongariro, a temperature lapse rate of 5.96°C/1000 m was calculated. This allowed the extrapolation of the Dome shelter record back over the ~20-year period of the EOSS study.

Dome Shelter rime ice

Ruapehu climate graphs

Ruapehu’s glaciers have behaved similarly to those in the Southern Alps in recent decades, but with noticeable exceptions. The glaciers share the summit with the Crater Lake and other vents: centres of frequent geothermal activity. As such, on top of climate trends, Ruapehu’s glaciers are also heavily influenced by the mountain’s volcanism. For example, the phreatomagmatic and strombolian eruptions of 1995-1996 caused mass gain on the summit plateau ice field through insulation of underlying ice by thick tephra deposits. In other areas thin tephra mantles absorbed solar radiation and locally reduced the albedo, resulting in accelerated melt and compounding mass losses related to lahars. The Tuwharetoa Glacier, the only glacier to experience persistent positive mass balance on the mountain, actually owes its enigmatic growth to a lahar, and the consequent lowering of Crater Lake into which it formerly calved, which allowed the glacier to surge across the newly exposed lake bed. Lee-side accumulation of snow and solar shielding by surrounding peaks helps sustain this stoic exception to Ruapehu’s rule.


Glacial responses to volcanic phenomena are generally short-lived however, and climate remains the most important control of Ruapehu’s permanent ice. The major drivers of New Zealand climate (temperature and precipitation) at a sub-decadal timescale are the regional- to hemispheric-scale atmospheric circulation regimes of the El Niño Southern Oscillation (ENSO) and the Southern Annular Mode (SAM). The SAM refers to the strength of the southern polar vortex: when atmospheric pressure is low over Antarctica the southern mid-latitude weather systems speed up. Positive mass balance of New Zealand’s glaciers appears to be correlated to El Niño conditions (the negative phase of the Southern Oscillation Index or SOI), when we experience increased southerly and westerly airflow, but its relationship to the SAM is not yet well established.

While the 20-year record presented in this study suggests that the Whangaehu Glacier has been approximately in equilibrium during this time, the trend of increasing positive degree days is worrying. It may be that this hiatus in retreat will soon end and the mountain’s glaciers will resume their slow death as global temperatures rise: an unnaturally warming backdrop on which regional climate variability will continue to operate. It will be a great shame if, through the total loss of Ruapehu’s remaining glaciers to unchecked anthropogenic global warming, we — much like Harry in Hemingway’s poignant short story — are left only with the regret that we didn’t make the most of our experience and capabilities in the time that we had.


This research project would not have been possible without the support of Dr. Andrew Mackintosh (ARC – field work and academic supervision), Dr. Brian Anderson (ARC – automatic weather station installation and monitoring) and Dr. Harry Keys (DOC – aerial photography for EOSS study).


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Reflections of a Sound Matthew Wood Aug 25

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When you’re spending US$15M to drill a hole, you want to make sure it’s in the right place.

In the austral summer of ’05/’06, it was still a year until bits would start chewing through rock beneath the McMurdo Ice Shelf (MIS) in the first phase of the ANtarctic DRILLing (ANDRILL) Project. The international science team was busy wrapping up a multi-season geophysical reconnaissance effort, using multichannel seismic reflection profiling to hone in on the ideal site for the next season’s drilling. Using carefully-positioned geophone arrays and controlled (but by no means insignificant) explosive seismic sources, they remotely ‘imaged’ the sedimentary sequence that has gradually accumulated over the last 14 Ma beneath (what is currently) the McMurdo Ice Shelf. Accommodation space for these sediments was initially provided by regional subsidence related to extension across the Terror Rift, and later, from crustal flexure in response to the emplacement of the Ross Island alkalic volcanics.

MIS Project Setting

The ANDRILL MIS core was an unprecedented achievement in Antarctic science: 98% of the 1285 m sub-sea floor drilled sequence was recovered as core, sampling glacimarine sediments that document the Late Cenozoic, continental-scale fluctuations of Antarctica’s ice sheets. Currently at the drill site, the 85 m thick McMurdo Ice Shelf floats above 850 m of McMurdo Sound seawater (which posed a formidable logistical challenge for both seismic profiling and drilling). But as the sediments testify, this area has periodically hosted an expanded, grounded East Antarctic Ice Sheet, and at other times, sea ice-free, open water marine conditions. Following drilling, seismic reflection was again utilised to generate a down-hole vertical seismic profile, to more accurately tie the major lithological boundaries observed in the core to the major, and numerous second-order, seismic reflectors. This allowed the ‘ground-truthed’ geology of the drill site to be extrapolated laterally across the wider study area.

Dhiresh Hansaraj Erebus

Dhiresh Hansaraj was fortunate enough to contribute to both of these exciting field seasons. Interested in geophysics from early in his undergraduate studies, Dhiresh required little persuasion to take up a Master’s project with the ANDRILL team that involved the acquisition, processing and interpretation of MIS seismic data. Following university, he didn’t allow the lack of industry work in Wellington to stop him from pursuing a career in the scientific field he had learned and loved on the ice, and now co-runs his own seismic processing house, Black Mountain Seismic Ltd, which uses entirely New Zealand made software. His experience is a refreshing exception in an industry that generally lures our postgraduates overseas to work for the resource exploration and production giants.

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Photo (c) Dhiresh Hansaraj 2005. Figures from Scientific Logistics Implementation Plan for the ANDRILL McMurdo Ice Shelf Project

The Story Is in the Soil Matthew Wood Aug 03

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Much of the research previously showcased on Journeys to the Ice required highly complex fieldwork systems: oceanographic research vessels and drilling rigs can be stunningly expensive to operate, and may require months of concerted, 24-hour effort by legions of scientists and support staff.

The science in this episode of the podcast harks back to the old school of Antarctic field geology.

In late 2005, three ARC scientists were dropped off on a barren expanse in the McMurdo Dry Valleys armed only with a couple of spades, a measuring tape, a sachet or five of margarita mix (no room for beer in helicopter cargo allowances unfortunately), and with pockets stuffed with sample bags, set out to see what  paleoenvironmental tales might be hiding beneath their mukluk-clad feet.

These valleys are formerly glaciated, but are currently ice-free due to rapid uplift of the Transantarctic Mountains, which has locally halted the discharge of the East Antarctic Ice Sheet to the Ross Sea. Within the valleys, the sublimation rate far exceeds the negligible delivery of snow, resulting in a frigid desert environment that has been used as a terrestrial analogue for the surface of Mars.

McMurdo Dry Valleys Map

The term ‘soil’ is used loosely in the Dry Valleys — these are not the rich, fertile loams we enjoy here in New Zealand. The outwardly monotonous, highly saline, rocky sediments of the valley floors are devoid of organic material (apart from patchy populations of nematodes), but can contain interesting geochemical signals that the macroscopic profile belies.

10Be is a radioactive isotope of beryllium (1.4Ma half-life) that forms in the atmosphere from spallation reactions between incoming cosmic ray radiation and oxygen or nitrogen target nuclei. The free radionuclide binds to aerosol particulate matter and is quickly brought to the Earths surface in precipitation or dry fallout. In temperate and tropical regions, this radionuclide commonly makes its way down through the soil by fine particle translocation within percolating meteoric water, or in acidic solutions. The parched polar desert of the McMurdo Dry Valleys suffers no such pedological processes today, so when the then-Bavarian masters candidate, Martin Schiller (actually he’s still Bavarian but now has a PhD to boot), discovered a classic 10Be decay profile in a buried soil in the lower Wright Valley, he knew he must have opened a window onto an (at least marginally) warmer, wetter local climate of the past.

McMurdo Dry Valleys

The paleosol was overlain by an in situ 3.9Ma volcanic ash. Radiometrically dated tephras like this are usually ideal temporal marker horizons, but in this case, turned out to be a mixed blessing. Being devoid of 10Be, the ash’s presence dictated that the paleosol, and its accompanying paleoclimatic setting, must have been at least 4 million years old and therefore potentially active during the Pliocene. However, due to the release of large amounts of mineral-bound, stable 9Be during the laboratory procedure, the proposed decay-based dating model — based on the down-profile ratio of naturally weathered 9Be to atmospheric 10Be — was rendered unusable. While Martin’s work is a valuable addition to the growing body evidence supporting significant Late Cenozoic climate variability in the Ross Sea region (e.g. ANDRILL) it also serves as a lesson in just how tough the dating game can be.

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Photo (c) Warren Dickinson 2005

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