RACE TO SAVE SECRETS IN THE SAND THAT COULD BE LOST TO DEVELOPMENT WORK IN THE DESERT
Oxford University is analysing sand dunes to chart climate change and model the future, writes Daniel Bardsley
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, researchers are striving to ensure that does not happen here.
This year, Prof 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 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 work for an industrial project. But thanks to the efforts of Prof Thomas and his colleagues some of the information it contained has been saved.
“One of the big challenges in Arabia is to capture records of past events before they get destroyed,” he said. “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. In areas of northwest 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, which include the Kalahari and Namib deserts in southern Africa and India’s Thar desert.
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 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.
“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 he and his co-researchers have published is one from 2015 in Quaternary International, which 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 back other findings that during the early Holocene, the geological epoch that began about 11,650 years ago and continues 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 to analyse the samples from Prof Thomas’s latest trip, in late February, when he worked with his wife and researchers from the UK, 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 that contain 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, with 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 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,” Prof Thomas said. “It’s an old desert, it’s experienced many climate phases. There have been several green phases too.”
Knowledge of past climatic changes can be used to test computer models of how the climate will evolve in the 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 with an Oxford colleague, Dr Ash Parton, an archaeologist who has looked at river formation in Arabia over the past half million years to understand climate changes.
As reported in The National in 2015, he and his colleagues analysed a sequence of river sediments exposed by quarrying near Al Ain, which revealed that the climate of Arabia is 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 as far back as 130,000 years ago, not 50,000 to 60,000 years.
Now, Dr Parton is expanding his work into Oman and the eastern Hajjar Mountains, “trying to create a much more complete picture of environmental change and human demographic change”.
“People often say you need to understand history to know what will happen in the future with politics,” Prof Thomas said. “I would say the same with the environment.”
One of the big challenges in Arabia is to capture records of past events before they get destroyed