While planting trees is always referred to as one of the top solutions for climate change, some experts differ. Two new studies have suggested that planting more trees may harm the environment, instead of benefiting it.
Experts argue that while planting trees may help store a lot of carbon, they must continue to grow for a long period to be effective carbon reservoirs. Furthermore, the wood they produce must be used for a long time for the carbon it contains to not be released into the environment when it rots or is burned.
From a measurement and verification standpoint, planting trees is perhaps the most difficult potential technique. For forests to be effective, they must last for at least 100 years. Planting trees does not result in carbon retention and sequestration for at least 10 years after they are planted, therefore there is a significant time lag.
Because carbon persists in the soil for hundreds of years, soil sequestration, in which atmospheric carbon is pulled into the earth by regenerative agriculture techniques, is a significantly more effective approach.
It also functions as a highly effective fertilizer, eliminating the demand for synthetic fertilizers, the manufacture of which emits significant amounts of greenhouse gases. Soil carbon removal is by far the most cost-effective and scalable technology of carbon removal currently available.
More permanent solutions for long-term carbon storage are needed according to Christoph Beuttler, head of climate policy at Swiss direct air capture company Climeworks. CO2 is removed by trees, but is it permanent? What is the lifespan of the trees? What happens after that? Do they become charred? Do they get cut down for bioenergy?
Carbon capture and storage (CCS), in which carbon is mechanically removed from the atmosphere and pumped underground, or carbon capture and utilization (CCU), in which captured carbon is converted into materials, are longer-term solutions, according to Beuttler.
Other types of biomass, such as fast-growing algae, bamboo, and hemp, have been promoted as natural carbon sequestration alternatives, with hemp being “more effective than planting trees.”
Carbon capture at a rate of more than ten gigatons per year has been deemed required if we are to meet our climate targets. Geological capture and mineralization are currently the only methods for reducing inevitable carbon dioxide emissions from industrial processes like steel production. The first method compresses carbon dioxide into a supercritical fluid, which is then pumped into underground reservoirs. This method, however, must be kept totally safe to avoid explosive disasters like the one that occurred at Lake Nyos in 1986, when hundreds of people died as a result of trapped carbon dioxide being released during a probable volcanic eruption.
Mineralization, on the other hand, is significantly more inert. Carbon dioxide is incorporated into stable crystal lattices with calcium or magnesium oxides to produce their corresponding carbonates, rather than being trapped physically. Following that, the infamous greenhouse gas can be recovered as an ultra-pure feedstock or the carbonate can be incorporated into blended materials, resulting in the development of potentially profitable carbon-negative companies.
Though this isn’t to imply that mineralization is the be-all, end-all solution to climate change — a Google Scholar search for “carbon dioxide mineralization” gets over two hundred thousand pages, and yet mineralization has to find its way into the mainstream industry.
Planting trees need a lot of time and effort. We are in dire need of a solution that is effective for the generations to come and a combination of carbon capture and mineralization might just be that.