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Should we be growing trees in the desert to combat climate change? – TechCrunch

Reforestation is one of our best tools to combat the climate crisis. In the tropics, forests have been reported to absorb 10 million tons carbon dioxide per year. A mature tree can absorb about 48 pounds of CO2 per year. Our forests are stored in the USA 14% of all annual carbon emissions, according to the nonprofit American Forests. Without forests and trees, there is no path to climate neutrality.

Many companies like Foreclosure and Microsoft fund the planting of trees in burn scars and agricultural land. But the stealth phase startup subdesert is working on a whole new frontier for reforestation.

As you can probably guess from the name, the company focuses on planting trees in deserts, specifically desert scrubland in the Alamogordo region of New Mexico. Nicholas Seet, CEO of Undesert, calls his company “Climate Triage” – do something now to reduce emissions while the rest of the world catches up.

But should we plant trees in the desert?

“There is a current debate about whether drylands are suitable for reforestation for global climate change mitigation,” said Niall Hanan, professor of dryland ecology in the Department of Plant and Environmental Sciences at New Mexico State University.

Seet called the shrubland “unused, empty space,” but Hanan emphasized that these are valid ancient ecosystems with their own biodiversity, not simply degraded forests. And there’s a reason deserts don’t have trees.

“When [deserts] if they were suitable for trees, they probably would have trees in them,” Hanan said. Trees need sun, CO2 and water for survival. Deserts are drastically lacking in any of these ingredients, preventing most trees from growing naturally. But that’s a problem Underesert has avoided.

Undesert has optimized a water desalination technology so that it can produce 20 liters of water per 24-hour period and work with brine water that was previously too salty for reverse osmosis.

“The problem with [reverse osmosis] Technology is there’s a lot of waste brine that can’t be filtered anymore,” Seet said. “We can run reverse osmosis brine through our system and then you get pure water and salt.”

Undesert eliminated bottlenecks over a traditional solar greenhouse desalination technology, in which the sun heats a saline pool that evaporates to produce pure water that condenses on the greenhouse roof. Underesert developed a modular design to capture the water and was able to increase the efficiency by 5 times the pool evaporation. Instead of condensing on the roof, the condensation takes place in a separate chamber, which is cooled by hoses with circulating cooling water. In this system, more than 93% of the water in the brine is recovered as clean water. The entire process uses solar energy in a micro-grid, making the process low-emission.

Undesert works with Navajo Nations to harvest brackish groundwater that has become undrinkable due to salt concentration for its desalination technology. The company then uses drip irrigation to deliver the desalinated water to Afghan pines, the trees Undesert plans to use for its reforestation. The company has planted 16 of these trees so far. Undesert chose the Afghan Pine because it is desert hardy, requires little water, and grows fast, tall, and straight. The company also has 50 ponderosa pines under its irrigation scheme as its root system is well adapted to drought. But even if the trees get adequate water, there are other environmental factors like temperature that can affect the survival of the seedlings.

Without forests and trees, there is no path to climate neutrality.

According to Undesert, the small tree demonstration powered by solar desalinated water has been operational since September 2021 and is showing healthy development. The area has intense solar energy and available underground salt water. And the Alamogordo region, where the demonstration is located, borders the Sacramento Ranger District that has forests of Douglas fir and ponderosa pine and many more before they were removed for railroad tracks and maintenance. All of these factors give Undesert confidence that their trees will be a success.

But then there’s the scalability. Having an entire irrigation system for a large forest is not feasible. And using brackish groundwater might work in New Mexico, but Hanan noted that most deserts aren’t near oceans and don’t have easily accessible groundwater. Costs, labor and maintenance also add up quickly. Even just the trees can end up costing $1 million per square mile, according to Hanan, even if each seedling costs just $10. Most desert dwellers around the world do not have access to these types of funds.

And only obtain seedlings is already a major concern for reforestation efforts.

“Even getting 400 for the first hectare would probably be difficult,” Hanan wrote in an email. “It is unlikely that the nursery industry in the Southwest (or even the western US) could supply the 100,000 seedlings needed per square mile, let alone a larger acreage.”

But there are more questions than just tactical ones.

“In a place with severe water stress, like the US Southwest,” said Matthew Hurteau, professor of forest and fire ecology at the University of New Mexico, “if you have the technology to clean up that water in a relatively inexpensive and low-carbon way, it is raising trees in the desert is the best use of this water?”

Reducing carbon emissions and providing co-benefits to local communities by planting trees could be a very valuable use of that water, but experts like Hanan and Hurteau would expect a detailed cost-benefit analysis that would answer questions like:

  • How suitable is this land for trees?
  • Are these the right plants?
  • Are they native or exotic species?
  • What will they do with the existing ecosystems?
  • What will be lost in these systems by adding trees?

And will the stored carbon actually be enough to put a dent in our carbon problem? Hanan is skeptical because desert-grown trees will certainly not be the giant trees of tropical rainforests and will likely have a fraction of the biomass. Trees in the desert will probably never be the lungs of the earth, but can or should they be a tiny inhalation?

Should we be growing trees in the desert to combat climate change? – TechCrunch Source link Should we be growing trees in the desert to combat climate change? – TechCrunch

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