Heads in the clouds: how the UAE hopes to make rain for the good of the world

It may be tiny – not much bigger than a fingernail – but on its slight back the desert-dwelling beetle Stenocara gracilipes is carrying the weight of a nation’s freshwater hopes. That, at least, is one of the possibilities being explored by Professor Linda Zou, who in January was one of three international experts awarded […]

It may be tiny – not much bigger than a fingernail – but on its slight back the desert-dwelling beetle Stenocara gracilipes is carrying the weight of a nation’s freshwater hopes.

That, at least, is one of the possibilities being explored by Professor Linda Zou, who in January was one of three international experts awarded a total of US$5 million in funding by the UAE Research Program for Rain Enhancement Science.

One of her co-awardees is Masataka Murakami, a visiting professor from the Institute for Space-Earth Environmental Research at Nagoya University in Japan, who will be developing sensors and algorithms to identify the clouds most suitable for enhancement, or “seeding”.

The other is Volker Wulfmeyer, chair of physics and meteorology at the University of Hohenheim in Germany. He will be studying the relationship between areas where weather systems converge and the type of land surface beneath them.

The award is the first in what will be a series of annual grants to advance rain enhancement. In short, says Zou, professor of chemical and environmental engineering at Abu Dhabi’s Masdar Institute of Science and Technology, the UAE is at the cutting edge of research with vital importance to the whole world.

“This country, particularly the senior leadership, is extremely serious about rain enhancement, to which they have already committed much time and effort,” she says.

But while producing more water to replenish the UAE’s badly depleted groundwater reserves is important, says the National Centre of Meteorology and Seismology (NCMS), which manages the research programme, there is a wider goal.

With the UN predicting that half the world’s population will be short of water by 2030, the UAE “is driving the innovation needed to make rain enhancement a key tool in our efforts to ensure adequate supplies of freshwater for people in arid and semi-arid regions around the world”.

This work, says Zou, “is for all humanity. I think the UAE feels a genuine moral obligation to do the right thing and that’s amazing.”

Equally amazing is Zou’s project to see if the science of nanotechnology – engineering on a minute scale – can be harnessed to bring the currently somewhat hit-and-miss art of rain making into the 21st century.

Clouds are currently seeded by salt particles, which attract moisture to form droplets big enough to fall as rain. But nanotechnology, Zou thinks, could be used to fabricate new, more efficient and predictable cloud-seeding materials – and that’s where Stenocara gracilipes, a beetle that ekes out a living in the arid Namib Desert in southern Africa, comes in.

In 2001, two zoologists from Oxford University reported in the journal Nature their discovery that thanks to an ingenious pattern of tiny bumps across the insect’s wing coverings, water drawn from fog-laden wind formed in droplets on its back.

Alternately waxy and non-waxy, these bumps are either “hydrophobic” (water-repellent) or “hydrophilic” (water-attracting) and together create a system that allows the beetle to convert moisture in the air into water droplets that then roll down into its mouth.

At only the start of her three-year research programme, Zou is understandably reluctant to go into too much detail yet about any of her planned investigations, “but I can say I will be looking at bio-inspired materials – and the Namib Desert beetle”.

Whatever role nanotechnology might play, rain enhancement is a science long overdue a makeover. Its roots lie in experiments conducted in the US in 1946, when meteorologist Vincent Schaefer took to the skies over Massachusetts and persuaded a cloud to produce snow by seeding it with several pounds of solidified carbon dioxide, or dry ice.

During the Vietnam War, Operation Popeye was a five-year attempt by the Americans to disrupt enemy movement along the Ho Chi Minh Trail by seeding clouds with silver iodide to extend the monsoon season (leading the squadron involved to adopt the slogan “Make mud, not war”).

Countless other experiments have been undertaken around the world. In 2008 the Chinese used various chemicals in an attempt to “over-seed” clouds and prevent rainfall during the Olympics.

There is no definitive proof that either Operation Popeye or China’s Olympic efforts worked. Neither experiment or its results could be monitored or verified independently and, despite claims of success by the interested parties, neither the Chinese nor the US military were exactly transparent about the results. Uncertainty has always overshadowed the claims made for rain-making.

For example, Israel has long seeded clouds with silver iodide, which it claims has increased rainfall over the country by up to 15 per cent a year. But independent research published in 2010 looked at results going back as far as 1969 and found that rainfall had also increased in areas not affected by the seeding and was probably down to normal variations in weather.

In short, says Alan Gadian, a senior lecturer at the UK’s National Centre for Atmospheric Science (NCAR), the scientific jury on whether cloud seeding actually works is still out. “Some people do believe it works,” he says. “But the global meteorological community remains sceptical and that scepticism is based on the fact that it is very difficult to carry out convincing experiments.

“The challenge still is to answer the question ‘Does this actually work?’, and the evidence is that we don’t know.”

That, he says, is why the UAE research initiative is “a very welcome attempt to try to clarify what happens”.

The UAE itself has already come a long way in rain enhancement – about as far, in fact, as current know-how allows. The first attempts to persuade clouds to convert water vapour into rain drops in the UAE began as far back as 1990, and over the years the National Centre of Meteorology and Seismology has drawn on expertise from institutions including US space agency Nasa and the National Center for Atmospheric Research in Colorado. The NCMS has six Beechcraft planes fitted out with seeding flares that operate mainly from Al Ain and can be deployed at a moment’s notice.

But whatever the technology in use, the problem until now with cloud seeding has always been the difficulty of proving a link between cause and effect.

In 2011 The National investigated reports in the international media that a Swiss company had deployed an array of 10-metre-tall ionisers to induce rain to fall out of the clear blue skies above Al Ain on no fewer than 50 occasions.

It was true that an experiment had taken place. But after close examination the paper was able to report that “the rain in Al Ain falls mainly in the imagination of journalists”. Clearly, had the technology truly worked, today the UAE landscape would be covered in the umbrella-like pylons. In fact, there is no sign of the devices or the company that ran the trial.

Axel Kleidon, a biospheric scientist at the Max Planck Institute for Biogeochemistry in Germany, who in 2011 was an independent observer of the Al Ain trial, recalls that “unfortunately, nothing came out of the … study … the company had financial issues and we stopped evaluating their technology”.

In his view, “it will always be difficult to rigorously test and confirm if a rainfall event was caused by the treatment or if it would have rained anyway”.

Zou agrees. While cloud seeding clearly works, “we have no idea just how successful this is”.

“Recently a cloud expert said to me: ‘Every second, a cloud is different, so how can you show that the change is caused by seeding?’. And, of course, right now there is no ideal way.”

That’s why one strand of her research over the next three years will focus on “developing a numeric model based on cloud physics to allows us to compare precipitation with and without cloud seeding”.

If she succeeds, the sceptics will be silenced. Eventually, this computer model will also allow accurate predictions to be made about when, where and how much rain will fall.

Part of the lure of cloud seeding is how cheap the water it produces could be – an estimated 1 US cent per cubic metre (1,000 litres) versus the 60 cents the UAE pays for that much desalinated water. No one, however, expects rain-making to replace desalination as the UAE’s main source of drinking water – there is only so much moisture to be wrung out of the air and meeting the UAE’s per-capita consumption of more than 350 litres a day, one of the highest in the world, will remain a job chiefly for industrial-scale desalination.

But an expanding urban population and rising demand for water is putting huge pressure on groundwater supplies (one Environment Agency Abu Dhabi report said reservoirs could be depleted within 50 years unless urgent action was taken). Therefore, the UAE is rightly exploring every avenue to find alternatives: greener desalination technology, powered by renewable energy, to innovative cloud seeding. Conservation (water fees had been recently raised) is also crucial – and some hotels now reuse water for certain functions.

“Rain enhancement offers as yet unrealised potential,” wrote Alya Al Mazroui, programme manager for the Research Program for Rain Enhancement Science, in a recent article for the journal WaterWorld.

While it was “difficult to quantify the precise extent to which rain enhancement could add to the UAE’s existing reserves of fresh water” – some estimates have suggested by up to 5 per cent – it was hoped that “refinements of existing technologies along with new innovations could increase water levels in existing catchment areas and provide a valuable supplement for use in the industrial and agricultural sectors.”

Over the years there had been “encouraging results”, he said. In April 2013, intensive seeding of clouds in the Al Quaa region of Abu Dhabi coincided with a monthly rainfall of 136 millimetres, “a significant amount given that the average April rainfall level for the area between 2003 and 2014 was 29.9mm”.

NCMS records show that between 2003 and 2014 the mean monthly rainfall for April in the UAE as a whole was just 8.4mm.

But despite such successes, “significant technical and data-gathering obstacles remain”, acknowledged Al Mazroui. “One of the key technical challenges faced is finding the means to accurately measure the extra precipitation generated.”

As the UAE research programme embarks on strengthening both the science and the evidence base for cloud seeding, Zou ponders that success in the skies over the UAE may create alternative challenges on the ground. “If we can make rain enhancement more efficient and predictable over the long term, it may even be necessary to build more reservoirs and dams to capture it,” she says.

Not to mention road drains. Anyone who has driven along the Sheikh Zayed Road during one of the UAE’s occasional heavy downpours will have experienced the flooding that takes place – flooding that after an extremely heavy downpour last month limited the connection between the two emirates for 24 hours. Heavy rain fell, says Zou with a chuckle, just as she was signing her contract with the Research Program for Rain Enhancement Science. As the NCMS said, 77 cloud seeding operations took place between January and the end of March – more than three times on the same period last year.

Source: art & life

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