Have you ever seen scientists listening attentively to research talks whilst sitting, standing or lying on the sand? Well-known scientific personalities presenting their results on an improvised black board leaning against a four-wheel drive vehicle, or an acacia tree (we avoided camels which definitively move too much)? If not, you should have taken part to the first of six international meetings on "Rapid and catastrophic environmental changes in the Holocene and human response". This conference was held in Mauritania from 4 to 18 January 2004, with the first week along the coast of the Nature Park of Banc d'Arguin and the second one on the Adrar plateau. In attendance were 29 participants from 17 countries who were drawn there to examine in the field various phenomena linked to the theme of the meeting, with the emphasis on past and recent desertification. Nearly 40 research communications were presented on topics ranging from palaeoenvironmental history, climate modelling to fulgurites. An interesting feature was the presence of a journalist who specialises in weather and climate issues.
The structure of the conference was unusual: field visits in the mornings and afternoons and oral presentations before lunch and before dinner. The participants were from north-Europe, south-Europe, north-Africa, Australia and north-America, facilitating N-S and W-E exchanges. Young scientists just finishing their PhD thesis were able to share closely the everyday life of colleagues recognized on the international scene. All the talks were translated in English and French, by bilingual volunteers. But in the vehicles, during the meals or during the three day trek across the sand dunes, the conversations were often in a curious mix of languages indicating the desire to communicate by any means.
Our group was formed, not only of experienced field researchers, but also of climate modelers, both of whom study the early Holocene when the Sahara was green. The rains of October and during the meeting, having greened the desert, gave us a virtual taste of life in the Sahara 6000 years ago. We missed only the cattle and the giraffes that we saw in the rock art. The rain did however result in swarms of migratory locusts, which cause the terrible damage to local vegetation including the gardens that local people depend on. During the last evening, it was not sure if some participants would be able to get hold of some of their luggage stuck on the wrong side of a wadi that the rains had now flooded. For some of us, our thoughts went more to the lost opportunity of scientific observation of a flood than to the unlucky participants. Starry nights were unfortunately few and our imagination was overworked after the sighting of fresh hyena footprints.
Amongst the topics presented were the following. 1) the new curve of the diatom biovolume from lake Malawi and its relation with solar irradiance and its impact on fisheries over the last centuries; 2) the preliminary study of phytoplankton influx in sediment traps off Cap Blanc attempting to show a link with climatic parameters; 3) the use of aeolian sediment in Algeria and Morocco to show a link with recent climatic and land use changes; 4) the impact of natural catastrophes such as tsunamis, earthquakes, karstic collapse, floods, and rapid coastal siltation; 5)New dating techniques that have the potential of detailed time resolution (U series) and 6) new proxies such as fulgurites formed when lightening strikes sand. One of the most heated debate concerned the relative influence of natural and human impact on desertification and what the term itself means. All the abstracts are available on http://atlas-conferences.com/cgi-bin/abstract/camu-01.
The field conference ended on discussions on the role of scientists, what we can and have should do and how to transfer our knowledge to the wider public. We left behind new links with the department of geology of the University of Nouakchott, plans to organize field excursions for our students and contacts with the natural park of the Banc d'Arguin that will soon see posters on their walls on palaeoceanographic and palaeoenvironmental studies done off the Banc.
We are planning to publish our results in a special issue of the Geological Society of London entitled: "Holocene Catastrophes and Rapid Environmental Changes, Recovery and Human Response" whose editors are Leroy S., and Stewart I..
We wish to leave behind three messages. 1) it is necessary to study the past. Geosciences can provide information that is resolved at time scale relevant societal issues and can help to find the right indicators of future changes. 2) multidisciplinary studies are already providing valuable insights into the impact of rapid and catastrophic changes on past societies. 3) analyses of environmental changes, while accounting for the impact of anthropic actions on societies and the environments should not minimize have negative effect the harmful effects of natural processes.
We are very grateful to the sponsors of this conference: ICSU Dark Nature - Rapid Natural Change and Human Responses 2004-2005; IGCP 490 The role of Holocene environmental catastrophes in human history (2003-2007) for 2003; IUGS- GEOIND Geoindicators Initiative, INQUA, The Royal Society, IAG, UNESCO, Hommes-et-Montagnes and Brunel University.
Suzanne Leroy, Brunel University, UK
(photos: R. Cheddadi and F. Marret).
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