How giant tree walls help stop a growing “Mad Max” hellscape for desert cities

Outside the city of Karbala in central Iraq, a wall of date palms and olive trees about 100 meters wide sways in the dust. Its north axis extends far around the city in a 26 km arc. Its southern axis extends an additional 13 miles.

The trees weren’t always there. This natural windbreak was first proposed in 2006 as a measure to protect the city’s 576,000 residents. Dust storms that sweep Iraq every year wreak havoc on the streets and hospitalize thousands with respiratory problems. Some even kill. The tree wall of Karbala was designed to both calm the storms and filter the smallest dust particles from the air.

Such green belts have become increasingly popular as countries in arid regions grapple with increasing dust storms. Global warming and ineffective water management have increased droughts in some areas by almost a third since 2000. Drought, in turn, increases the likelihood that strong winds will collect sand and dust particles on their way to populated areas. The Iraqi government expects the country to experience 272 dust days annually for the next 20 years.

Tackling the root cause of the problem – climate change – requires a global effort. But protective windbreak structures like those around Karbala represent a possible paving solution. Such a belt of trees around an urban area in Dubai could reduce dust in the air by up to 22 percent.

“If they’re tall trees, they absorb some of the dust in the atmosphere as they pass,” Nick Middleton, a physical geography colleague at Oxford University, told The Daily Beast. “It gets deposited on leaves and therefore not in the area you’re supposed to be protecting. You can use it as a kind of barrier for the dust itself.”

The tree walls also help communities in other ways. They improve air quality by acting as CO2 sinks, cool the surrounding atmosphere, create new habitats for animals, and their construction brings money and jobs to low-income communities. But they are also full of challenges.

Greenbelts require massive funding to cover the cost of labor and the trees themselves. With Karbala’s green belt and others, those big budgets may prove too attractive to corrupt officials in some states. “They could have a big pot of money,” Middleton said. “But if someone diverts it for other things, then it’s not serving its purpose.”

In fact, engineers were never able to complete the original 47-mile plantation in the Iraqi city. Around 16 billion dinars ($11 million) have been earmarked for the massive project. Only nine billion ($6 million) has ever made it, according to a former Karbala city councillor.

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Even with access to the necessary funding, the tree walls require an enormous amount of effort to maintain. China’s nearly 2,800-mile “Great Green Wall” was planted to prevent the spread of the Gobi Desert, the world’s fastest-growing desert, which engulfs 2,237 miles of grassland every year. But water shortages have repeatedly hampered efforts, and only 15 percent of the trees planted have survived since the project began.

Ali Al-Dousari, senior research scientist at the Kuwait Institute for Scientific Research, has helped develop several such projects. He believes a more natural approach could improve the chances of success. One of the main reasons the projects fail is the use of non-native plants, he said. These plants may need large amounts of water as their roots are adapted to a different environment. Native plants, on the other hand, often thrive when planted in the same spot.

“Native plants are the real solution for the future,” Al-Dousari told The Daily Beast. “The plants have the ability to capture, use, adapt to and stabilize the sand.”

The positioning of the tree protection walls can also make a difference, he said. Previously barren desert areas may not provide the right environment for vegetation to survive. His home country of Kuwait, for example, is attempting to plant a belt of trees near its desert border with Iraq – and he reckons it will fail at a very high cost.

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Green belts can even harm biodiversity. His research team noticed that the trees at one plantation they planted attracted large numbers of raptors, including eagles and hawks. Existing populations of lizards, snakes and foxes soon disappeared from the area. Another plantation on a Kuwaiti island changed the migration pattern of a rare species of bird that once laid eggs in the area.

“The ecosystem has changed as a whole,” he said. “You as a human are the most dangerous species, damaging the system by using solutions that are incompatible with this environment.”

Encouraging growth in areas where vegetation could otherwise thrive would be the best way forward, Al-Dousari said. His analysis found that organic matter, such as seeds and pollen, accounts for about 5 percent of the particles kicked up in dust storms. Growing plantations along the routes followed by dust storms could provide a self-sustaining solution.

Middleton thinks the success may be closer to the source of dust storms. “Once that stuff is in the air, it’s harder to protect yourself,” he said. “It might be that you would use your time and money more effectively if you could find out where it originally came from.”

Al-Dousari completed a tour of southern Iraq in January 2019 to collect dust samples at various locations along the Euphrates. He discovered two specific hotspots that account for up to a third of the dust blown into Kuwait. He is now trying to work with the Iraqi Ministry of Agriculture to stabilize the dust in the source areas.

“We don’t do research for the sake of research,” he said. “We are trying to help about 40 million people affected by these two trouble spots. And not only the 40 million, but also the coming generations.”