University of Oxford is charting environment change with sand samples ahead of industrial project, Daniel Bardsley writes from Oxford
As more of the UAE desert is churned up for development, one researcher seeks to preserve its secrets
In the great pursuit of economic progress, important aspects of the past can be lost.
And as developers push further into the desert to bring roads and homes to the UAE's population, a team of researchers are striving to ensure that doesn't happen here.
Earlier this year, Professor David Thomas of the University of Oxford was near the border of Ras Al Khaimah and Umm Al Quwain, collecting sand samples from a large section of dune.
About 50 metres wide and stretching around 500 metres long, this area of dune was all that remained of a much larger formation that had mostly been levelled to allow for development.
By now, even this remnant may no longer exist, swallowed up by preparatory work for an industrial project, but thanks to the efforts of Prof Thomas and his colleagues, some of the information that it contained has been saved.
“One of the big challenges in Arabia is to capture records of past events before they get destroyed,” said Prof Thomas.
“We’re trying to analyse records of long-term environmental change and looking at sites of human history before they get lost in the course of development.”
Prof Thomas is a physical geographer who, for the past three decades, has been trying to gain a better understanding of how the climate in the world’s deserts has changed over time.
In temperate regions, finding out how the climate changed can be easier. For example, in areas of north-western Europe, peat samples can be collected and their pollen record analysed.
There is no such pollen record in the deserts of Arabia – or in the other desert regions Prof Thomas studies. Instead, analysing the age of sand samples can offer insights into how the climate evolved.
As is now well established, there have been times when Arabia’s climate was significantly wetter than today and the land was covered with vegetation, allowing soil to develop.
By looking at the ages of multiple sediment sequences, often exposed by quarrying or development, it can be determined when wetter and drier periods occurred.
“We’ve build up this complicated, detailed picture of how the deserts in parts of the Emirates have evolved over 120,000 years,” said Prof Thomas, who works in Oxford’s School of Geography and the Environment and who has also studied the Kalahari and Namib deserts in southern Africa, plus India’s Thar desert.
“What I’m interested in is how deserts have expanded and contracted in the past and how that has affected human use of the landscape.
“When I started doing this in the 1980s, people used to think of what I did as a hobby: ‘It’s interesting, but what’s the point?’
“But there’s such a change, with awareness of global warming, that reconstructing the past has been seen as a tool for understanding the future.”
Among the studies Prof Thomas and his co-researchers has published is one from 2015 in Quaternary International that used sand samples from RAK to highlight a wetter phase that began about 8,500 years ago, as indicated by lake development, before things turned more arid.
The results tie in with other findings that during the early Holocene, the geological epoch that began about 11,650 years ago and continues until today, the climate was often wetter than now, but there have also been drier and windier periods when the major dunes developed.
This summer, a postgraduate student will start analysing the samples from Prof Thomas’s trip in late February, when he worked with his wife and researchers from the United Kingdom, France, Italy and elsewhere. It will be incredibly painstaking work.
A bucket of sand from an Arabian desert is about 90 per cent quartz, with much smaller amounts of feldspars, which contains radioactive elements, and, if the sample was collected near the coast, tiny shell fragments.
The feldspars release electrons (negatively charged particles) that become trapped in micro-fissures in the quartz grains, their numbers building up over time. When the grains are exposed to light, the electrons are released from the micro-fissures.
Each sand sample consists of a circular column of sand a few centimetres in diameter and about 20cm tall. The top and bottom sections of sand are discarded, as they may have been exposed to sunlight, and what remains goes through three acid washes to clean up the quartz grains.
These grains are then picked up individually using tweezers and exposed to light and radiation in a light-tight chamber. In the procedure, known as luminescence dating, the quantity of electrons released indicates the sample’s age.
“The whole history of the desert is very, very complicated. It’s an old desert, it’s experienced many climate phases, there’ve been multiple green phases too,” said Prof Thomas.
Knowledge of past climatic changes can be used to test computer models of how the climate will evolve in future. If these models are run backwards, they generate results that can be compared with what actually took place. If their modelling of the past is accurate, their forecasts for the future should be too. The hope also is that the geological information provided by the sand will tie-in with archaeological information.
Prof Thomas is now working closely with an Oxford colleague, Dr Ash Parton, a lecturer in the Department of Archaeology, who has looked at changes in the pattern of river formation in Arabia over the past half million years to understand climatic changes.
As reported in The National in 2015, he and colleagues analysed a sequence of river sediments exposed by quarrying near Al Ain.
Their analysis indicated that the climate of Arabia made he area suitable for human habitation every 23,000 years or so, instead of every 100,000 years, as had previously been thought. In turn, this indicated that humans may have left Africa for Arabia as far back as 130,000 years ago, not 50,000 to 60,000 years back.
Now, Dr Parton is expanding his work into Oman and the eastern Hajar Mountains, “trying to create a much more complete picture of environmental change and human demographic change”.
“It’s creating a whole landscape picture,” he said.
So, as these researchers and others continue their sampling in the UAE, and from this make inferences about the climate in the past, we should gain a better understanding of the changes the world’s climate is likely to experience.
“People often say you need to understand history to know what will happen in the future with politics. I would say the same with the environment,” said Prof Thomas.