In an opinion article released in the journal Trends in Plant Science, plant experts contend that addressing the excess carbon dioxide levels in the atmosphere requires more than just emission reductions. It needs ‘re-greening’ efforts
One potential solution to the carbon capture challenge could be found in arid regions like deserts.
CO2 sequestration in arid lands
The authors make the case that by strategically manipulating the interplay of plants, soil microorganisms, and soil composition, known as ‘re-greening’, we can potentially convert arid ecosystems into highly effective carbon-capture systems.
This transformation would enhance soil quality, optimise photosynthetic processes, and increase root biomass. The ultimate goal is to harness the natural biogeochemical process known as the oxalate-carbonate pathway to create subterranean carbon storage reservoirs.
“The advantage of reclaiming arid regions for re-greening and carbon sequestration is that they do not compete with lands used in agriculture and food production.” writes the research team led by senior author and plant scientist Heribert Hirt of King Abdullah University of Science and Technology.
Re-greening: Greening the Desert
This approach leverages arid-adapted plants that naturally produce oxalates, carbon and oxygen-containing ions that might sound familiar if you’ve experienced kidney stones or gout. Certain soil microbes thrive by utilising oxalates as their exclusive carbon source.
As these microbes consume oxalates, they release carbonate molecules into the soil. Typically, carbonate breaks down rapidly, but when these plant-microbe systems are cultivated in soils that are alkaline and rich in calcium, the carbonate combines with calcium to create enduring deposits of calcium carbonate.
Carbon undergoes a natural cycle, moving between the atmosphere, oceans, and terrestrial ecosystems. However, human activities have led to an excessive buildup of CO2 in the atmosphere. Even if we can reduce CO2 emissions, the researchers write that” climate effects of elevated CO2 will remain irreversible for at least 1,000 years unless CO2 can be sequestered from the atmosphere.”
While trees are often viewed as an excellent means of capturing carbon, reforestation efforts directly compete with agriculture for fertile land. In contrast, arid lands, which comprise approximately one-third of the Earth’s terrestrial surfaces, are not utilised for agricultural purposes.
Arid ecosystems as carbon sinks
Arid ecosystems have limited plant life due to water scarcity, but some plants have adapted to these conditions. They’ve developed unique strategies like deep root systems to find water, efficient photosynthesis to reduce water loss in extreme heat, and “oxalogenic” plants producing oxalates that can be turned into water during droughts. These plants also store carbon as deposits underground, which the authors aim to harness for carbon sequestration.
“Overall, in this form of carbon sequestration, one out of every sixteen photosynthetically fixed carbon atoms might be sequestered into carbonates,” the authors write.
One out of every sixteen photosynthetically fixed carbon atoms might be sequestered into carbonates
According to the authors, boosting this naturally occurring biogeochemical process in arid regions has the potential to transform unproductive and deteriorated ecosystems into carbon storage areas with improved soil and plant conditions. They propose starting with “fertility islands,” small revitalised zones where plants and microbes can increase and eventually expand to create a lush vegetation landscape.
The authors anticipate that these strategies could substantially grow plant and soil carbon sequestration within a decade. They acknowledge that the effectiveness and pace of this approach will be influenced by the plant growth rate, which tends to be slow in water-scarce environments.
Furthermore, they emphasise that the successful implementation of re-greening technology in different arid nations will hinge on financial and political support.
