Category Archives: Conferences

Reflections on the Nitrogen Cycle and the Anthropocene workshop: Part 1

A big thanks to Melanie Leng, Carol Arrowsmith and other for putting the workshop on The Nitrogen Cycle and the Anthropocene together. It was a thought-provoking meeting and a great opportunity to both catch up with former colleagues and meet new faces.

I’ll start with a overview, largely for my own notekeeping on some of the points raised in the keynote talks, first quoting (copying and pasting) their abstracts where available, with the addition of a few links which I hope will be useful. This is part one of a two or three part entry.

Jan Zalasiewicz (University of Leicester): Stratigraphy of the Anthropocene: an overview.

“Human-driven rapid and large-scale change to the Earth system have led to the suggestion that we have left the Holocene to enter a new epoch of geological time: the Anthropocene Epoch. The term was proposed little more than a decade ago by Paul Crutzen, the Nobel Prize-winning atmospheric chemist, and has since been widely used – and sharply debated. Its status as a potential new unit of the Geological Time Scale needs evaluation by considering the various kinds of historical and environmental change in terms of geological – or more precisely stratigraphic – change. Lithostratigraphic change, for instance, is strikingly represented by the spread of ‘urban stratum’, the refashioning of sand, clay and limestone into your building, foundations and transport systems. Biostratigraphic change include the ongoing mass extinction event and the effect of invasive species (while deep human-made bioturbation in the form of extensive mine and borehole systems comprises a novel aspect in the fossil record). Chemostratigraphic changes include the reshaping of the Earth’s carbon, phosphorous and nitrogen cycles. Many of these transformations occur, though, at different times in different places. So, can an Anthropocene Series be effectively characterised and mapped across the Earth’s surface? Ongoing efforts to answer this question should help in the understanding of the Anthropocene as a new development within Earth history.”

Jan convenes the Anthropocene Working Group of the Subcommission on Quaternary Stratigraphy (International Commission on Stratigraphy).

Jan took us through a thought-provoking, nicely-illustrated and intriguing fact-filled (e.g. number of tonnes of plastic produced per year) presentation about the ways in which we might characterise the different stratigraphic components of a potential Anthropocene Epoch. The parts that particularly struck me were the ‘new minerals‘ being produced anthropogenically and how these metals, plastics and other compounds and how these are becoming, or will become, new rocks and new strata. In terms of the biostratigraphic signature he reminded us of the ‘homogocene’ term (e.g. Rosenzweig, 2001).

Jan encouraged us to question and ‘throw bricks’ at any of the ideas of how best to characterise and find the way to characterise the Anthropocene. His feeling was that nuclear signature might be the most distinctive and most easily traced stratigraphic tie-point between different types of depositional archive.

Questions about a potential tension between geological definition/identification and the emotive issues that the term invokes was raised.

Another idea was to consider the inter-planetary nature of the Anthropocene with footsteps on the moon and space vehicle debris…

This presentation reminded me of the BSG (British Society for Geomorphology) debate in 2013 at the annual meeting, held at Royal Holloway University of London, ‘Is there a geomorphological case for the Anthropocene’ (the link is a video of the debate, chaired by Stephen Tooth) and the importance the BSG community place on being involved in this debate and discussion. Tony Brown (one of the panellists) had led a 2013 paper in ESPL on this.

Within this, I should also flag up the paper by Jonathan Dean, Melanie Leng and Anson Mackay on isotope geochemical signatures for the Anthropocene. 

Tim Heaton (British Geological Survey): Sediment, soil and plant records of changes in 15N/14N ratios during the Anthropocene

“The annual production of reactive nitrogen compounds (nitrate, ammonium, etc) by human activities now exceeds production by natural processes; thereby more than doubling the amount of nitrogen available to the earth’s biosphere. If this ‘anthropogenic’ nitrogen finds its was into a lake then it may change the isotope compositions (15N/14N ratios) of the different components of the lacsutrine system. Crucially, because this anthropogenic nitrogen has mainly been produced in the past 100 years or so, it might be recorded in terms of a change in the 15N/14N ratios of the recently deposited sediment. Evidence for these changes is presented, and their significance discussed in terms of: differences between inhabited and remote environments; possible influences of diagenesis; information from terrestrial plants and the possible influence of other factors impacting on the nitrogen cycle.” 

Tim took us through the headline that since the 1980s the anthropogenic production rate of nitrogen compounds exceeds the natural production rates. Related to this point, I highlight the headlines that this has huge implications for the nitrogen cycle – in 2009 this made up section of a paper in Nature about the ‘safe operating space for humanity’. See a Yale BLOG post on this.

Tim’s focus was on lake sediments that record this anthropogenic nitrogen, showing us records from Lake Alexandrina in Australia and Lake Biwa in Japan, in which the increase in nitrogen is accompanied by a corresponding drop in the d15N. He also showed us other records from further afield, with examples from the Science paper by Holtgrieve et al. (2011) and remote lakes by Wolfe et al. (2013).

In summary Tim concluded that:

  • the decline in the d15N signature in lake sediments was real, and not entirely from diagensis in the sediment.
  • the favoured reasons for this decline were
    • the composition of atmospheric deposition (but there was poor, or a paucity of, evidence for anthropogenic N compounds have sufficiently lower d15N signatures
    • the amount of N deposition changing (increasing)
    • a potential link with atmospheric CO2 and the effect this has on soil de-nitrification.

Some useful links to work on diagnesis include a modelling study this year by Brahney et al. (2014).

If anyone has links to explanations about how the increased input of nitrogen (amount) compounds leads to an excess of inorganic nitrogen that Tim discussed, I’d be really interested to read more and try to get my head around this idea.

A reference relating to CO2 and N cycle with a focus on the oceans. Hutchins et al. (2009).

Thanks Lizzy for this recommendation of a paper discussing the links between global C, N and P cycles by Gruber et al. (2008).

Which is a good place to link Tim’s talk and emphasis on the last 100 years or so with the story of nitrogen cycling over the longer timescale of the Holocene (if this epoch isn’t subsumed, or made obsolete, by the Anthropocene). The changes in nitrogen cycling over the Holocene, recorded in a global-scale synthesis of lake records, by Lizzy and her colleagues Kendra, Joseph W and Joseph C (all at Kansas State University) can be found in Nature in 2013 (McLauchlan et al., 2013).




The Nitrogen Cycle and the Anthropocene

N cycle

Next week (Wednesday 29th October) the British Geological Survey at Keyworth are hosting a workshop on The Nitrogen cycle and the Anthropocene.

From the advertisement flier for the event:

“The rationale for this is that there are several types of temporal record (ice cores, sediments, tree rings) which show a reduction in 15N/14N ratios during the ‘Anthropocene’, a period in which there has been a substantial increase in the amount of reactive nitrogen in the earth’s nitrogen cycle. These changes are thought to be mainly due to the industrial synthesis and application of fertilizers, other changes in farming, and the combustion of fossil fuels. However, there does not seem to be any general agreement on the mechanism/s which cause this change in 15N/14N ratios, or indeed whether the changes in different records are related.

The workshop will therefore aim to promote discussion around: 15N depletion in organic matter in recent lake sediments; the lag between 15N in recent ice cores and lake sediments; recent 15N changes in modern plants/trees and soils; changing sources of N in glaciers and ice cores; and on how changes in source inputs to the atmosphere, and/or changes in its chemistry processes during the past few hundred years might have resulted in a decrease in 15N/14N of deposited N?”

There will be both keynote talks during the day and posters on display. The keynote talks feeature a stellar line-up of Earth Scientists.

  • Jan Zalasiewicz (University of Leicester): Stratigraphy of the Anthropocene: an overview.
  • Jan Kaiser (University of East Anglia): Isotopic evidence of sources and chemical processing of nitrogen in the atmosphere.
  • Eric Wolff (University of Cambridge): Ice core signals of a changing nitrogen cycle.
  • Tim Heaton (British Geological Survey): Sediment, soil and plant records of changes in 15N/14N ratios during the Anthropocene.

stone_edmunds joae paperI will be presenting a poster Naturally-high nitrate in unsaturated zone sand dunes above the Stampriet Basin, Namibia which is the output of a paper in the Journal of Arid Environments with Mike Edmunds, that shows: (i) high natural nitrate production in the unsaturated zone sediments above the Stampriet Basin. most likely from vegetation; (ii) that this high nitrate is variable across space; (iii) that nitrate is being introduced as pulses and moving toward groundwater and (iv) this finding is in line with observed nitrate concentrations in other drylands. Elevated nitrate is a difficult water quality issue to manage in dryland environments.



20th Windy Day meeting in Oxford…

Wednesday 8th October was the 20th WINDY DAY meeting: Annual discussion day for aeolian research in Oxford. I will be talking in the morning session about: Rapid assessment of (range finder) luminescence ages? as applied to the Namib Sand Sea.  

windy dayStephen
The meeting was dedicated to the memory of Stephen Stokes, iniator of the Windy Day meetings. The photo on the left was not a ‘windy day’ in Oxford, but is from Chesil Beach.

Annual BSG Conference at my new University home

Between the 1st and 3rd of September the University of Manchester hosted the Annual Conference of the British Society for Geomorphology (BSG) Geomorphology: Past, Present and Future. This also marked my first week in my new job here as a Lecturer in Physical Geography.

BSG posterI presented a poster  Dating desert dunefields (the Namib Sand Sea).’ which reported progress on some research with Prof. Mark Bateman (Sheffield) and Prof. Dave Thomas (Oxford) on comparing the signals from a portable luminescence reader with full OSL dating protocols.

Canadian Conference Calling

7-14th July was the 14th edition of the Luminescence and Electron Spin Resonance Dating conference (LED) in Montreal, where I presented a poster with Mark Bateman (and other members of the Working Group on Sand Seas and Dunefields), which compares the output from a portable reader with full laboratory measurements of the quartz signal using a SAR protocol. Dating large dunes in the southern Namib using OSL’

micheleWe were hosted by the ever-enthusiastic Michel Lamothe and his team from the Lux Luminescence Dating Laboratory. The week was full of high quality luminescence dating excitement in both the applications of the dating technique for geological and archaeological applications and the fundamentals of the technique.

(Practising) communicating geoscience (Posters and Pritt Sticks?)

I am presenting a poster at the IAG (8th IAG International Conference on Geomorphology – August 27th to 31st, 2013) in Paris next week. Eating lunch amongst humanities colleagues this week, the idea of a poster at a conference raised some chuckles and offers of Pritt Stick. This perhaps highlights some of the challenges of communicating how research is communicated in my field of geoscience (and in many other science disciplines) to other academics. So, where does this leave the much thornier issue of communicating science to the public?

Jon Tennant, who blogs at an EGU (European Geophysical Union) hosted blog GREEN TEA AND VELOCIRAPTORS, wrote (back in Oct 2012) about communicating research and knowledge to a wider public. This was orientated around ‘why bother’ and ‘what might the public audience already know’, which very effectively sets up an idea both of the motivation and the context to any endeavour to communicate geoscience research to the public (probably largely through blogging). Jon’s work was itself prompted by work by Prof Ian Steward and Ted Nield.


I have previously produced 1-page handouts (snippet in the picture) for land-owners at my sampling sites to give an idea of why I spent a few days digging holes into the sand in the heat of the desert.

So. The research I’m presenting next week, quite honestly didn’t start out as much. No pressing question set up in an academic paper, no large grant was awarded, rather it was an interesting view driving through the stunning Namibian landscape on the way to (another) conference, hosted at the Gobabeb Research Centre. After miles of mountainous terrane, and a descent down the hair-pin bends of the Gamsberg Pass, a very familiar colour of sediment to me was seen at the side of the road – red sand dunes (I’ve spent plenty of time digging holes into red sand dunes, sporting terrible fashion sense, both in the Kalahari, and the Namib Sand Sea, to the top of the latter we were travelling).


Drilling holes in sand dunes 

I asked my travelling companion, a Namibian Geographer, if he knew where that beautiful red sand had come from, and he didn’t have an answer. Stopping for a cool drink at the lodge named after the red sands (Rooisand) it seemed they also weren’t completely sure, but that it was suggested the sand had blown over and down the mountain pass we had driven down, having starting off in the Kalahari, famous for it’s long, red, linear sand dunes. Once at the conference, I still couldn’t find the definitive answer I was looking for, with someone else suggesting the sand might have blown up north-east from the Namib Sand Sea (which would make it the most northerly part of the sand sea). So, on the way home, armed with some cutlery and sampling tubes, I decided to collect a bit of this sand for analysis from an exposure at the side of a dry river bed.


The exposure where samples were taken

… At this point it is worth asking you (the reader) whether asking ‘where the sand has come from?’ is an interesting enough question worthy of some geoscience research and effort? Maybe it is. However, much of my research field of Quaternary Science (go on, Google/ Wikipedia it) is about asking what piles of sediment (and other deposits like ice) can reveal to us about what the climate of the past was like. In this light, the question becomes when and by what process (wind deposition, water-deposition followed by wind deposition) did this loose sand accumulate here, and what was the climate like in order for this to occur? Today, the area is very dry, and only seasonally windy enough to move some of it around. Was this different in the past?

rooisand from the air

Rooisand from the air (via GoogleEarth) 

So, now I had my sample, how was I going to settle the question of where this red sand came from? The term that’s used in geoscience for this is ‘provenance’. In addition, what might I be able to say about how long the red sand had been sitting there in the landscape for folks like me to catch a glimpse of as we travelled past on our way to the Namib Sand Sea or the coast (or how old the Rooisand deposit is)? A cool technique to establish this, is known as luminescence dating (making sand glow to establish how long it has been buried under other piles of sand, but that will have to be the topic of a separate blog post). My poster for next week is therefore imaginatively entitled ‘Age and provenance of the dunes of Rooisand’.

So, here beings my communication challenge.  What has been done with those samples to answer my questions? (my methods). And, what do the results of these tell me, and my coauthors, that the answer is?

And a reminder of the possible answers about Rooisand provenance: from the Kalahari, from the Namib Sand Sea, or an alternative idea that it is very locally sourced (material eroded from the surrounding mountains).

When you take a handful, or even a fingerful, of the red sand and put it under a microscope it isn’t all red sand at all. Some of it is white, some milky-white, some translucent, some green, some shiny black, etc. etc. (I’ll try to source a picture, but it’s not quite as cool as the ocean sand pictures that have been doing the Twitter rounds, largely because it is not as full of old marine life). This microscope vision is not only pretty, but pretty useful for working out where the sand came from (provenance). In Italy, after some preparation, including putting grains onto slides, (to make it easier to tell exactly what these sand grains of different appearance are) Mara Limonta and Giovanni Vezzoli at the University di Milano-Bicocca counted and characterised a few hundred grains. They had been doing this for lots of other piles of sand collected from other sites in Namibia, some from river valleys, some from Kalahari, some from the Namib Sand Sea.

What all of this microscope work revealed is that samples from different locations contained different amounts of various minerals and heavy minerals (by this I mean an array of terms, some of which may be more familiar sounding than others – quartz, K-feldspar, plagioclase, muscovite, biotite, epidote, amphibole, zircon, rutile, tourmaline). Ultimately, the details of what the minerals are is not crucial to the story. What is, is that the hard-rocks at the surface of the earth (what we could call the bedrock geology, or consolidated hard rock material, as opposed to the soft sands at Rooisand) in different places contain different combinations and proportions of these minerals. In effect, the sediment (whether rock or loose sand) has a fingerprint. So, once a rock has been broken down by weathering into smaller grains of sand, and redeposited somewhere in the landscape (like at Rooisand), it is possible to use it’s fingerprint to work out where it came from. Similarly, the difference between sand sample fingerprints (from different river channels and areas of sand dunes) can be instructive.

It was a diagram plotting the difference between these sands that arrive in my inbox from Italy last month for presenting on the poster.


The plot from Italian colleagues

In this plot the squares represent river sands, the stars wind-blown dune material, and the straight coloured lines are a sneaky way of plotting lots and lots of information about what minerals are in the samples without being constrained to two simple axes:  x (horizontal) and y (vertical) axis. In addition, the closer a box or star is to a line the more of that mineral (the coloured line) that sample contains. In addition, the closer the boxes and stars are to other boxes and stars, the more similar their fingerprint is (and therefore, they are very likely to have come from the same place and same bit of hard-rock geology). So, in short that plot shows me that the Rooisand sample (RS12/1) is most similar to samples from Rivers Gaub, and Kuiseb and closest to the coloured lines that represent heavy minerals such as garnet (and also apatite and amphibole) (all in the top left-hand box). The sample is very different to bottom right-hand box, where the sand samples from the Kalahari are plotted (so, I’m afraid I will have to tell the barman that served our cool drinks that the idea they have at the Rooisand lodge is wrong).

So, if the Rooisands are most similar to Kuiseb River sands and contain garnet, apatite and amphibole, what does this say about their provenance? Those suites of minerals are derived from a geological unit known as Damara metasediments (metasediments are sediments that some time after deposition, become subjected to heat and pressure, with changes to their properties, as mountains, like those in this part of the Namibian landscape are formed). These Damara metasediments form a band that runs through the Rooisand area, and so are very local.

To be able to answer the question about the age of (the last) sample burial event, I am awaiting one last piece of data (about something called dose rate, again this will have to be the subject of that other post on luminescence dating). What I can currently estimate is that this exposure close to the river bed is only a few hundred years old. It was deposited on that occasion by the wind. The average size of the grains is just over 300 microns (that’s 0.3 of one of those millimetre lines depicted on rulers), and this requires wind speeds of over 8 meters per second to move the sand. If all 10 meters of the exposure were deposited around a similar time in the past, then it would suggest that winds were over 8 meters per second sufficiently often during those years to move and then put back down 10 m of red sand. That’s a windier environment than today.

So here ends my first rehearsal of science communication, and as well as being slightly too long, it has revealed to me a more pressing question, why are the Rooisands, red sands (and not any other colour)? After all, that is what about them that caught my eye in the first place, and made the Rooisand lodge suggest the sand had travelled from the Kalahari. In short, they are coatings of iron oxides (just like rust). This rusting occurs in dry environments when the sediment and iron minerals are directly exposed to the atmosphere. The complicating factor is that it is possible the red coatings on these grain could have been inherited from the much-older geological hard-rock, or have accumulated since the soft sand sediments were deposited. This geoscience question currently remains unanswered.

Talking (to each other) about research at/through Gobabeb

September 2012 saw the Gobabeb Research and Training Centre host/house two excellent academic conferences – that of SAAG (the South African Association of Geomorphologists) and SASQUA (southern African Society for Quaternary Research).

In addition to a full programme of talks and posters, some short outings to the Kuiseb and surrounds and plenty of dune-scrambling, there was (at SASQUA) a short meeting to discuss the future of research involving Gobabeb. To this end, I’ve created a blog page, which I hope might provide a platform to continue these discussions. and I would like to add anyone who is interested and thinks this type of tool would be useful to be an admin/author of this blog, to be able to contribute!

Blogging a conference: Day One of Deserts… (old blog posts)

posted 15 Apr 2010 07:07 by Abi Stone   [ updated 1 May 2010 03:22 ]

Blogging a conference… 

(and put in charge of a voice recorder also, for podcasts. Does this mean that I am becoming an embracer of technology, rather than a technophobe?)

The Significance of Deserts in Shaping the Evolutionary History of Homo sapiens. 
We kicked off with Mike Petraglia from the School of Archaeology in Oxford talking about how deserts may have shaped the evolutionary history of our genus ‘Homo’ and our species ‘Homo sapiens’. He started by claiming controversially that he is not interested in deserts (well deserts per se), rather it is the fluctuations in these environments and how these have influenced human population, in terms of evolution and perhaps extinction that is interesting to him.
He broke down the previous hypothesis/model that 130-80 ka was a ‘failed dispersion’ out of Africa (itself based largely on genetic coalescence data) and put forward an alternative hypothesis that migration out of Africa at this time was in fact ‘successful’ as based on field evidence from Africa and Arabia. Look out for forthcoming publication, in press, in the Annuals of Human Biology Out of Africa: New Hypotheses and Evidence for the Dispersal of Homo sapiens along the Indian Ocean Rim. Mike called for more field data and dating of more sites to back up this hypothesis.(2) Interpreting geo-proxies of late Quaternary climate change in African drylands: implications for understanding environmental and early human behaviour. 
This was followed by a very interesting presentation double act by Dave Thomas andSallie Burrough looking at ‘geoproxies’ and controversies in reconstructing environmental conditions in southern African drylands. This is a talk from the meeting in Argentia and will appear as a paper in a special issue in Quaternary International soon – look out for this paper, it is going to be a good one, and spell out much of the change of thinking that has been going on here in the Arid Environmental Research Group over the last 5 years or so. Some important messages here for Quaternary scientists, of which I will list a few:

* Sampling biases exist in our datasets, which become apparent as we collect more data (this is exactly what my poster next month at EGU is about!).
* Review paper: there are 3 in the last few years (4 from 2002) which make use of much of the same data but come to different conclusion. People are sneaky and use the evidence that best fits their hypotheses…
* Don’t forget the errors associated with dates. The suggested phases without errors from primary papers get regurgitated in review papers and somehow become fact… (see chapter 10 of my thesis for this rant also!)
* Histograms of age frequencies from records across the Kalahari are sampling site bias! and might be meaningless!
* With OSL dates 5% errors are the best we can get
* Advocated the use of a presence or absence of ages in 1 ka bin widths as an alternative to the histogram. (one problem is losing the error information).
Read this paper in QI when it is published!(3) Groundwater age and renewability in NW China 

Professor Mike Edmunds brought us closer to the modern day for the first time at the meeting, presenting work on groundwater recharge rate assessment in China (co authors John Gates, now in the US and Li Ma, postdoc in Oxford). He posed one simple question – “is the water in deserts, and beneathe deserts, part of the active hydrological cycle or part of a past hydrological cycle?” This has huge impacts for society and resourcse sustainability and renewability, or not!
These approaches use chloride as a tracer and mass balance approaches to calculate rates of most mmodern recharge. Mike showed us results from the Minqin Basin and the Badain Jaran desert (see the papers by John Gates in NW China and also result from northern Africa). The difficult message from this research is that groundwater, on which the populations of these arid areas rely, are not renewable, being used far more quickly than they recharge. This calls for new approaches in management and education.

(4) Livelihood sustainability in drylands
Andy Dougill, head of the School of Earth and Environment at Leeds University then spoke to us about sustainability of livelihoods. He highlighted that he has details of 7 case studies available for those who would like to see examples of these ideas, and that these will appear in an special issue of Ecology and Society. His focus is on the local scale – how livelihood systems in drylands are affected by drought, and a call for a critical reflection on integrated modelling approaches. The tag line is ‘closing loops’.

(5) Rejecting authenticity in the desert landscapes of the modern MIddle East (Oman)
Dawn Chatty from the Refugee Studies Centre, University of Oxford, kept us in the realm of modern human environments in deserts, looking at the interaction between human populations and the environments in Oman, middle East and the role of different scales of policy management, from the head of state, through middle management to the tribal people. Dawn brought us a great deal of knowledge spanning work with the UN from the 1980s to the present day.

(1) Dust in the Sahara 
Richard Washington
 from this host department took us back to Africa after lunch with his presentation about dust in the Sahara, reporting on the work completed in thBodele Depression and his plans for forthcoming work in the western Sahara.  
With respect to the Bodele work he answered three important questions:
1) why does this region produce so much dust?  – Bodele is located in the ‘bulls eye’ of windspeed over a depression (the Bodele Low Level Jet) (see Washington and Todd, 2005)
2) what can we learn from the past? – The depression has filled with water a number of times during the past 18 ka, and deposited the diatomite sediment that is now easily deflated. E.g.
(Washington et al., 2006). Topography is also very important. Removing topography from the model, wind speed reduces by 30 %.
3) what is predicted for the future? The Bodele Low Level Jet is predicted to get bigger in the future… have a look at Washington et al. (2009).
Richard also set out his plans for the forthcoming field campagin to investigate dust loadings in the west Sahara (FENNEC).

(2) Climate change and cultural transitions over the last 160,000 years in NW Africa.
Angela Vaughan,
 kept us in northern Africa, looking at the record preserved in the Grotte des Pigeons at Taforalt in Morocco. This cave is an important one, as it contains one of the longest, and potentially continuous sequences of environmental and archaeological change. Angela talked us through a number of the sectors of the cave. At sector 2, layer 14 (dated to 45-50 ka) suggests the Alterian was longer lived than generally perceived. There is a halt in evidence around 25 ka, suggesting a break in the occupation of the cave, over which LGM layers are found. Above this different lithics are from the iberomaurusian. An intensification of the use of the cave is indicated from 13-11 ka, with evidence for modern behavioural traits, such as burial practices. This culture also practiced the removal of the two front teeth. Angela will continue to reconstruct the local environmental conditions at this site and link these to marine record (see Sanchez-Goni et al. 2008 for some of the story so far).(3SW Libya between development and conservation 

Marina Gallinaro, from the University of Rome, presented on the Holocene records of the Libyan Sahara. She highlighted the issues of preservation of these records in light of the development in the Libyan south, which is having wide impacts. What struck the audience perhaps most was the puzzling motication for the human destruction/ graffiti of the rock art in the region.

(4) Human economic impacts of the Saharan interior: The case of addax 
Tim Wacher from the Sahara Conservation Fund kept us in the realm of the impacts of humans, this time from the wildlife perspective. He used the example of tracking the behaviour of the addax Addax nasomaculatus, and their response to traditional human caravan routes through to modern mineral extraction. The population is currently around 200. Aerial surveys and sight reports were used. In summing up he examined: What are the causes of econimc impacts in deserts? – the need for oil, coming from outside the Sahara (e.g. China). What are the shifts in biodiversity? –this will depend on knowledge and attitude of the developers. It is not necessary to crash across the system. Development can be more sensitive to the ecology and this is what the Sahara Conservation Fund is working hard with the government to achieve.

(5) The Mali wetlands: predicted river flows, inundation and water resources 
Simon Dadson, working at the Centre for Ecology and Hydrology, presented results from land surface- atmosphere modelling study, looking at impacts of changing water resource management on evaporation from the land surface in the Mali wetlands. The land surface is sensitive to configuration of soil moisture and other available moisture. Looking at the feedbacks from the large wetland innudation to atmospheric moisture, which provides lots of local rainfall and storms (up to 50% more). They are striving to understand how far this impact reaches – what is the footprint – few 100 km or even further into the regional climate. If we manage these water resources, perhaps we are also impacting regional climate? With a proposal to build a large dam, this will increase rice production, but effect bird populations, also downstream flows and perhaps regional climatology.

(1) Groundwater and irrigation in Balochistan Pakistan 
Daanish Mustafa, from King’s College took us to the semi-arid province of Balochistan in Pakistan where there is a transition in the approach to irrigation from the traditional karez system to groundwater pumping via tubewells. In this water scarce area groundwater is the mainstay and the past and future of drylands is ties to this. There is a connection between water use and cultural and political Talibanization, with a change to community leadership structures as the technologies of water use change. Water is the key to more than livelihood, and is deeply connected to culture/ identity and community. Whilst land is almost infinite, water is precious. Kareez used to work on a principal of access to water over a certain number of hours and the division of upstream and downstream access helped to ensure the sustainable preservation of the water in the Kareez. The tubwells have disrupted this and put access to water into the hands of the few, who have become very powerful. The predatory pumping of water has facilitated inappropriate farming, such as apples and coriander, which are not the right crops for this region. Daanish argued that protection of the kareez irrigation is an environmental, economic and social necessity, and this must be at the core of development objectives for a sustainable future.

(2) Inferences on retrospective climate of the Thar desert through luminescence dating of aeolian and lacustrine sequences. 
Ashok Singhvi, from the Physical Research Laboratory, Ahmedabad, India claims to take us  back to drier topic – geomorphology, archaeology and palaeoenvironment (but in fact right back into my direct area of interest). He showed a fascinating brief historical overview of the work that has been done in the region since the 1970s (with lots of contribution by Oxford geographers and archaeologists, from Martin Williams, Andrew Goudie, through the work of the RLAHA in the region today with Mike Petraglia). He highlighted that to cover the Quaternary record in this talk would take a rate of 100 ka per minute!
Some very important major messages were reiterated by Ashok:
a) the sedimentary record is episodic – short periods of intense aggradation and long periods of quiescence. Issues of thresholds, timelags and preservation must be considered.
b) gradients: climatic gradients and changing boundaries of dune activity through time.
c) the vital importance of stratigraphical information alongside chronological data, for example digging trenches in aeolian units and also using thin sections. The concentration of carbonate in some regions of the sand were high enough to rewuire 8 m depth of sand, but this no longer existed. The thin sections revealed a stacked sequence, so in fact the calcrete had formed during multiple cycles beteween 62 and 58 ka in which sediment was depoisted, then removed, aggradated again, and then removed.
d) short windows available for aeolian accumulation and preservation (a 13 ka peak in the record). This message, reiterated from Nick Lancaster and others at INQUA in 2007 – ‘small windown of opportunity’ for accumulation, relating to sediment supply, windiness and vegetation (with a useful figure to illustrate has these things relate to sand mobility).
e) with human activity the rates of dune migration appear to have increased tenfold (from 0.9 cm/y to up to 9 cm/y)
f) a break down of the old (and still regurgitated) view of the LGM as a peak of aeolian accumulation. In fact the peak of aeolian accumulation is well after this, and is a period of transitional climate in which the active/stable dune boundaries have progressively shifted over a gradient from SW to NE.
g) environmental changes and response to climate does not need to be synchronous, and indeed does not appear that way in the preserved record!
Other important ideas   Another important message is about climatic gradients in the Thar desert.

(3) Living off uncertainty

Saverio Kratli, editor of Nomadic People spoke about the problems faced when trying to understand rangeland ecology because of the failure of standard statistical techniques to capture the true nature of the system (asymmetric distributions, upon which dryland pastoralism relies upon). Things such as nutrient concentration are unstable and distributed asymmetrically, and understanding this is vital if we are to maximise production of economic value. Pastoralism exploits this asymmetric distribution of nutrients with herders monitoring the animals, rather than the grasslands and making sure that the animals have access to the best available grass, rather than simply eating ‘more grass’. In summary: (1) instability is not an obstacle, even if it seems as one (2) however, resource-scarcing models still frame unpredictable ecological variability as unfavourable and (3) the tools we use to analyse are not correct and exclude the approach of pastoralism. The statistical approaches that have been used hide exactly that which they are supposed to highlight.
see some of his work here

(4) Knowledge systems have not served the drylands well

Mike Mortimer continued the theme of questioning the underpinnings of approaches and knowledge systems with respect to drylands. He reflected on the knowledg e system and how to influence policy makers. The role of stakeholders in knowledge systems is complex and we need to understand the geography of scientific knowledge uptake. There are multiple paradigms, the access to science varies, students from dryland environments that move away to study can be treated as outsiders once they return. There are many myths that hang around in the understanding of drylands, and it can be hard to break these down.

(5) Water landscapes in Central Sahara
Savino di Lernia 
from the University of Rome took us back to Sahara from the final time in day 1. The main aim of his work Water in the Desert was to assess the water resources available in the area – producing a repetory of the natural (gheltas) and artificial (excavated wells and abonkor) water-related features for the first time, from the Mountains in SW Libya in the southern Sahara . The second aim was to analyse the relation between water and people in prehistory. He considered use of water since the beginning of the Holocene (through rock art) to the present. This work finds that the distribution, size, geomorphological context, vegetal landscape, period of activity and accessibility are key factors for the understanding of the role of water points, settlement systems and mobility strategies within the kel Tadrart Tuarge community.



Dave Thomas 
gave us the keynote address at the close of the day, something ‘non-academic’ in a sense, to mark the first integrated deserts conference in Oxford, he put together a (likely incomplete, and occasionally error filled) history of Oxford Geography to desert science.
Listen to the podcast for an entertaining and informative history!
The talk has a focus on the natural-based environment side of Oxford desert geography. It is a great to feel a part of such a distinguished community – even if Oxford Deserts work started in Cambridge!

… and Day two.
(1) Hominin dispersals and the Middle Palaeolithic of Arabia

Huw Groucott from the School of Archaeology in Oxford brought us back to topic that started day 1, taking us to one of the regions introducted by Mike Petraglia – the Arabian Peninsula, and particularly Saudi Arabia. His focus is on pluvial records, from alluvial fans, palaeolakes, palaeosols, speleothems and hippo teeth. The reulsts from his reconnaiscance trip has identified 25 new sites wih middle palaeolithic significance – many with lithic artefacts. It will be very important to find examples of buried artefacts, rather than surface lithics, as these can be put into context and most importantly dated. This will extend the understanding of hominin occupation past the Holocene and into MIS 3, which is a debated pluvial in the region. Previous work in this region by Mike Petraglia and his team is published in Antiquity.

(2) The role of the desert in forming the ancient Egyptian civilization
Mohamed Abouelata 
from King Saud University, Saudi Arabia talked about the formation of ancient Egyptian civilization and the role of the desert. He shed light on how the civilization used the resources of the desert. For example, use of 7 soft quaried stones for buildings, mining of metals and gemstones for arts, burial and preservation of bodies in the dry sand of the desert. The role of the desert resources may lead us to replace the famous motto of Herodutus ‘Egypt is the gift of the Nile’ with ‘Eygpt is the gift of the desert’.

(3) Water infrastructure and innovative technologies in arid climates

Lisa Mol, presented this paper on behalf of Asisa Chaouni and Liat Margolis from the Department of Architecture, University of Toronto, Canada. This work inv estigates the water infrastructures in cities as components that are rarely viewed as ground for designers. In desert climates the efficiency v. conservation dialectic is at its most extreme. Some of the innovative technologies that support water infrastructure in arid urban centre were presented and analyzed. See more about their work in thisBlog talking about strategies against desertification.

(4) a break from the Programme line up – Maria Mango stood in, with a talk about Androna in the Mediterranean, and a site, which was a staging post on a Roman Road.
This large site (160 ha) has different boundary walls. Was the expansion and contraction linked to climate or invasions? She spoke about the hectares of land needed to support the different sizes of population.

(4) “The cake will be shared by all” in the urban desert: The Black Panthers of Israel 1971-1975.

Anne-Marie Angelo a PhD student at Duke University gave us a history of the Black Panthers movement/ political party in Israel, which was in operation briefly from 1971-1975. This movement was modelled on the US Black Panthers.

(1) Environmental change in oasis systems
Caroline King
a DPhil student, here in the School of Geography, University of Oxford, presented the results of environmental changes over the past 50 years in oasis systems from 3 sites – Nefzaoua, southern Tunisia and the north of the Western Desert of Egypt. This research uses a mixture of remote sensing, national statistical data and research archives alongside surveys of the cultivators in this region to identify the environmental changes that have taken place. In particular, Caroline highlighted issues regarding how to manage these water resources. For example, whilst some attempts have been made to reduce use by concreting up wells, this only leads to the water emerging elsewhere.

(2) Wet rocks, big trouble? Using novel techniques to assess rock art deteriotation.
Lisa Mol 
stepped back up, this time to give us an insight into her research into rock weathering. This work involves measurements of rock surfaces both out in the splendour of the Golden Gate National Park in South Africa and in the laboratory. Lisa uses ERT (electrical resitivity tomography) to investigate internal moisture within the sandstone rocks. The rows of electrodes shoot 12 V of electricity into the rocks. Over a periods of just 1 year there are dramatic changes in the profiles measured between two field seasons. Lisa showed us these results alongside data-loggers of temperature in the field. In the laboratory the role of moisture and heat has been investigated. Add salt to the sandstone and weathering accelerates!
Lisa has two publications relating to this work so far… In Archaeometry andGeomorphology.

(3) A new estimate about the evaporation in the deserts of northwestern China 
Xiaoping Yang, from the Institue of Geology and Geophysics, Chinese Academy of Sciences, Beijing presented his new estimates of annual evaporation from the Taklamakan and Badain Jaran Deserts in China. One of the particularly fascinating parts of the presentation for me were photographs of perched water/moisture in sections cut through these dunes. These contain moisture contents as high as 10-15%. The presence of these small pockets of moisture may help explain the ability for plants to persist and for the ‘green-ness’ of the desert (and maybe sustain those Gerbils we met at Narabeb in the Namib Sand Sea?).
Mean annual rainfall has previously been reported to be as high as 2600mm to 4000 mm in the study region. However, new estimates from Xiaoping, using a modeified Penman Equation and weather station records suggest lower values – of around 1040 mm from lake surfaces and ~ 100 mm from the land surface in the SE part of the Badain Jaran Desert. The use of evaporation pans to previous estimate rates is not necessarily very representative of what is happening at the land surcace. If we are thinking of ‘myths’ – things that get reported as fact might not be true. The metal pan is different from sand.
The implication of these reulsts is that as much as 5 % of modern precipitation could be infiltrating to the groundwater aquifer (and lead to recharge!). This contrasts with the findings of John Gates and Mike Edmunds that recharge rates were ~ 1.7 % or lower. See publications in Hydrogeology Journal, and The Holocene. 
All interesting food for thought re. my future research plans.

(4) Gateway of India: the implications of palaoenvironmental change in the Thar desert, NW India, for the dispersal of Homo Sapiens. 
James Blinkhorn, from the School of Archaeology in Oxford, gave us the final installment of the hominin dispersal story, and also allowed us to return to the Thar Desert for the second time this conference. The Thar is thought to have been one of the last inhabited regions on a latitudinal belt before humans move north and south. There are some particular controversies over environmental conditions inOIS 3.
There has yet to be a systematic investigation of the rich Palaeolithic archaeological record in the Thar desert to investigate the dispersal of Homo sapiens and this has not been integrated effectively with the palaeoenvironmental record.
James outlined his planned season of fieldwork, which will help to address disparitied between the palaeoenvironmental and archaeological evidence.

(5) Environmental changes in the arid-semi arid western Pampas 
Marcelo Zarate 
fromthe Universidad Nacional de La Pampa, Soanta Rosa, Argentina presented the work by Quaternary geologists and sedimentologists from Argentina in the Western Pampas, focussing on the last episode of activation. This occued during the 1930 decade, and seems to have a parallell with the dust bowl times. Was there an interhemispheric linkage?

(1) Modelling the emission and transport of Saharan dust

Jamie Banks from Atmospheric Physics, here in Oxford presented his results of 3D modelling desert dust lifting and transport and compared this with predicted mineral dust loading over the Saraha from AERONET ground stations and satelitte instruments (SEVIRI, AATSR and MODIS). This region produces a LOT of dust – 1157 Tg in the period between March 2006 and Febuary 2007. The model predicts the path of transport with reasonable accuracy, and 62 Tg of this dust makes it make off the coast of west AFrica into the Atlantic.

(2) Casting new light on late Quaternary environmental and palaeohydrological change in the Namib desert: a review of the application of OSL. 

My turn (Abi Stone) to talk about role that OSL has played since 2002 in improving our understanding of palaeohydrological and palaeoenvironmental change in the Namib Desert. There are three important developments: (i) understanding dune migration rates in large complex linear dunes, alongside use of ground penetrating radar (GPR) to establish sedimentological strucutres; (ii) application alongside detailed fluvial lithofacies approaches which have been vital for clarifying the palaeohydrological interpretations of the deposits of the ephemeral rivers that cross the Namib Desert and (iii) applicaiton to sand units that interbed water-lain calcareous rich units, to revise the 14C chronologies, based on unreliable open-system carbonate systems. Watch this site for news of finishing this review paper…

(3) Minimum carbon payment along an aridity gradient for dryland forestation
Henri Rueff 
from the Centre for Development and Environment, University of Bern presented the economics of reforestation in Non Annex I dryland countries. Planting trees in these regions has an important impact on carbon drawdown, and the farmers are being payed for this carbon drawdown. Henri compared 30 years of the net productive value from carbon with net productive value from agriculture to consider whether this is worthwhile for farmers. There are issues relating to the amount of water the tree plantations take, as compared to agricultural land use. The policy implications are putting structures and intermediaries in place to ensure yearly payments to the farmers (rather than one bulk payment). The Clean Development Mechanism, whilst attractive to government agency must also be worthwhile for famers.

(4) Soil moisture and feedback cycles: southern Africa as a carbon sink. 

Andrew Thomas from Manchester Metropolitan University, kept us both informed and entertained in the last presentation of the conference with an excellent presentation on the weird and wacky world of semi-arid soils, biological crusts and CO2.
Current understanding of dryland respiration is insufficient to enable prediction of the consquence of these changes for soils of CO2 fluxes. Using a transect of sites in the Kalahari Andrew and colleagues have determined the effect of temperature, light and moisture on the soil inorganic carbon balance using what look like minature greenhouse pods from which to collect the gas for analysis.
Soil moisture is the primary limiting factor to respiration, with increases in (simulated) rainfall. Wet soils, plus higher temperatures further increase respiration (hotter northerly sites losing more organic carbon after rainfall than cool southerly sites). The autotrophic organisms in the biological crusts respond very quickly to rainfall, creating a temporarily ‘green’ surface. These photosynthesise, take up CO2, therefore muting net respiration rates.
Their revised model considers the complexity biological crusts add to diurnal variations in soil respiration. Predictions for the future are that warming will lead to higher soil carbon losses from the Kalahari Sands due to respiration, and that intensification of grazing results in the break-up of the crusts further increasing atmospheric CO2.

Posters were displayed alongside a wonderful gallery of desert-research photographs that featured on the BBC Earth News. Poster topics ranged from Hot Rocks to Dry Trees. Posters were by

CaitlinManal Abou El-Kassin and Mohamed Hossain from Fayoum University, Eygpt; Christine McCullough from OUCE; Lisa Mol from OUCE; Troy Sternberg from OUCE; Heather Viles from OUCE; Vanessa Winchester from OUCE; Yang Yu from Department of Sociological Studies, University of Sheffield.