Meteorologists link El Nino weather phenomenon and UAE rainfall

An Abu Dhabi study has shown that El Nino in the Pacific Ocean plays a part in weather in the UAE three months down the line but researchers also found that the country's construction boom is leading to higher temperatures.

A mirage forms because of heat on Sheikh Zayed Road in Dubai. Pawan Singh / The National
Powered by automated translation

Better known by his Spanish ­title of El Nino, this strange warming of part of the Pacific, long linked to wild weather across the globe including the UAE, is ­petering out.

And not before time. Notorious for its outbursts every three to seven years, El Nino has proved particularly hot-tempered this time.

It helped to stoke global temperatures by 1°C in February – the biggest leap in recent times. That, in turn, helped make last year a record-breaker for major hurricanes, and a year of droughts in South America and downpours everywhere from China to northern California.

And some say it brought about last month’s floods in the UAE.

The idea of anywhere in the Arabian Peninsula suffering floods may strike those unfamiliar with the place as almost a definition of weird weather.

Yet those who live in the UAE know it’s far from unusual, with floods having struck in 2008 and 2013, when El Nino was taking a break between tantrums.

The sheer complexity of the climate makes linking phenomena such as El Nino to specific events such as those floods all but impossible.

What is needed is hard data, and a start on providing it has now been made.

A team led by Mohamed AlEbri, of the National Centre of Meteorology and Seismology in Abu Dhabi, published an analysis of more than 30 years of rainfall data from almost 100 weather stations.

Their aim was to find evidence of a genuine connection between rainfall in the region and the strange events in the Pacific, more than 15,000 kilometres away. And they have found it.

Within about three months of El Nino emerging in the Pacific, the UAE starts to feel the effects, with the time delay reflecting the huge distances that have to be travelled by the atmospheric impact.

Yet as ever with climatology, the connection is not a simple one.

While the team's results, published in the latest issue of the journal General Scientific Researches, confirm that the appearance of El Nino in the Pacific usually presages wetter weather in the UAE, the level of rainfall and timing of its arrival varies considerably.

Sifting through their data, the team also found evidence that the UAE is susceptible to the flip-side of El Nino, a cooling of parts of the Pacific known as La Nina, or The Girl.

As one might expect, this is linked to periods of drought, and again the intensity and timing varies.

Over the decades, each takes turns influencing events in the UAE, but the researchers found that in the long run there is a slow but steady shift towards lower rainfall.

“The UAE keeps on shifting from the normal to arid conditions,” the team says.

The most obvious cause is the single most powerful contemporary climate effect – global warming.

Its influence on the Arabian Peninsula is certainly causing increasing concern among climatologists, who fear the region may be turning into a global hotspot.

Last September, the journal Nature Climate Change published a study by US climate modellers Jeremy Pal and Elfatih Eltahir, who used computer models to focus on conditions in the region.

They found wide variations for the impact of global warming, with some countries such as Kuwait and Saudi Arabia having modest rises in peak summer temperatures.

But parts of the UAE were found to reach combinations of heat and humidity that would show a searing 47°C on the thermometer, which feels like a life-threatening 80°C.

Without concerted effort to mitigate the temperature rise, the researchers warned that “even the most basic outdoor activities are likely to be severely impacted”.

Now there’s evidence that these potentially deadly conditions may come to pass sooner than expected through a home-grown cause: the urbanisation of the UAE.

In the past 20 years there has been a building boom in the region, with the coastline around Dubai in particular experiencing world-beating levels of construction.

Satellite imagery of the area over the past 14 years has shown the rapid spread of building but it also shows something else: a subtle darkening of the landscape compared with the brightness of the surrounding desert.

While barely perceptible this reduction in so-called “albedo”, or reflecting-power of the ground, leads to more of the Sun’s heat being mopped up rather than bounced back into space. That can turbo-charge temperatures.

Now this theoretical possibility has been confirmed by researchers at Tel Aviv University in Israel.

Emily Elhacham and Pinhas Alpert, of the department of geosciences, have used more than a decade of data from two Nasa satellites flying over the region to search for trends.

Reporting their findings in the journal Earth’s Future, they state that “temperature increases along with albedo decreases in the urbanised areas are pronounced”.

The biggest temperature increases were found in the newest areas of construction, where roads and buildings had cut the albedo and raised the heat by as much as 2°C in just 14 years.

That is about 20 times faster than the rate of global warming, about which there is so much concern.

Dubai has so far felt the brunt of this rise but preliminary data for Abu Dhabi and Sharjah suggest they are also starting to feel the heat.

The very shape of buildings is adding to the problem. While the temperature difference between the land and sea should lead to stronger sea breezes, the jagged skyline is damping them down.

In short, it seems that the extreme weather seen in the UAE over recent years is just a curtain-raiser for still more extreme conditions, with droughts and soaring temperatures becoming the new normal.

Some of this will be the result of the warming experienced by the planet as a whole but a significant part will be self-inflicted, as the buildings that dominate the skyline slowly turn the region into a man-made furnace.

Unless action is taken – and soon – the time may come when last month’s floods will seem like a blessing rather than a curse.

Robert Matthews is visiting professor of science at Aston University, Birmingham. His new book, Chancing It: The Laws of Chance and What They Mean for You, is out now.