turning the “sea of ​​death” into a carbon sink

For decades, the Taklamakan desertin the Chinese region of Xinjiang, has had a nickname quite eloquent: “the sea of ​​death.” And it is no wonder, since it is the second largest mobile dune desert in the world and a place where, historically, whoever enters does not usually leave. But faced with this major problem with sand for the surrounding areas, China decided to find a solution.

The solution. China since 1978 has been waging an ecological engineering war against sand with a very specific weapon: the Three North Shelter Belt Programbetter known as the Great Green Wall. A name that seems to come out of Game of Thrones, but its objective is to stop erosion and sandstorms.

But a new massive study published in PNAS has just revealed an unexpected and monumental side effect: human intervention has turned the edges of one of the driest places on Earth into an active carbon sink.

The data. The study has focused on 25 years of data obtained through field work and also with satellites. What the team has found on the margins of the Taklamakan is what they call a “cold spot” of carbon dioxide. This means that in reforested areas the concentration of CO₂ is between 1 and 2 parts per million smaller than in the surrounding environment. And although it may not seem like much, in climatology it is an outrage.

The trend in this case is quite clear, since The vegetation cover is increasing every yearand there is also a tendency for soil and plants to be “eating” more carbon than they are emitting.

How is it possible? The million-dollar question here is pretty clear: how do you keep 66 billion trees alive in a place where it barely rains? The answer lies in water management technology and species selection.

In this case, the project does not focus on planting oaks or pines, but is based on Extremophilous species like him Tamarixhe Haloxylon and the Euphrates poplar, which are plants evolutionarily designed to survive on very little. But the technological key has been the use of drip risk with saline water.

Origin of water. China discovered that under the Taklamakan there are immense aquifers, but they are too saline for traditional agriculture. However, these “halophytic” plants can tolerate it, so it seemed like it was done on purpose.

That is why groundwater is used to irrigate the protective strips that exist, especially around the famous tarim desert highway. The result with this is that soil moisture drops drastically between waterings, but the plants survive. And, although the salinity of the superficial soil increases, studies indicate that it is manageable in the long term and does not salinize the deep layers.

This has made it possible to complete in 2024 a “green belt” of 3,046 kilometers that encloses the desert, stabilizing dunes that previously moved meters each year.

Its stability. Unlike the Great Green Wall attempts in the Sahara, which have suffered from political instability and a lack of continued funding, the Chinese project has maintained its course since 1978. This continuity has allowed a “40-year experiment” that is now bearing fruit with important conclusions.

The Chinese authorities themselves cite that national forest coverage has gone from 10% in 1949 to 25% today, thanks in large part to this project. As a result, in places like Maigaiti in Xinjiang, sandstorm days have dropped from 150 a year to fewer than 50.

It is not the panacea. The source article warns of the limitations of this project: photosynthesis and carbon sequestration are strongly correlated with seasonal precipitation. This means that at least 16 liters of rainfall per month is needed in high season to maximize its effect.

But behind it is climate change that is drastically altering rainfall patterns in Central Asia, which could weaken the carbon sink. Although what is happening in Taklamakan is causing a paradigm shift, since now where we see reforestation of deserts, we also see a way to cool our planet by reducing the concentration of CO₂.

Images | Wikipedia Jasmine Milton

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