According to the UN, some “natural solutions” to CO2 absorption may put more strain on ecosystems than global warming itself.
Many scientists have discussed the possibility of harnessing nature to combat climate change by planting trees or crops to absorb CO2 from the atmosphere.
The new report from the UN’s Intergovernmental Panel on Climate Change, on the other hand, is more pessimistic, pointing out that relying heavily on these approaches may also pose real risks.
The nearly 4,000-page analysis, which was released last Monday, warns that more than 3 billion people worldwide are “highly vulnerable” to climate change, and that extreme events and other effects are already pushing human systems beyond their ability to adapt. Given the decades-long lag in transitioning away from fossil fuels, the researchers conclude that the world must quickly reduce emissions, adapt to changes already underway, and eliminate billions of tons of greenhouse gases that cause climate change.
Previously, the UN Intergovernmental Panel on Climate Change estimated that limiting global warming to 1.5 degrees Celsius would necessitate removing up to 8 billion tons of carbon dioxide from the atmosphere each year by mid-century, using bioenergy with carbon capture and storage, or BECCS.
This method makes use of crops’ and other plants’ natural ability to absorb greenhouse gases as they grow. These plants could then be used to generate electricity or fuels in specially designed facilities while capturing and storing the resulting emissions. At the moment, only a few such facilities exist, but there are a growing number of such projects in the works.
However, the UN report warns that planting enough crops to remove significant amounts of CO2 would necessitate vast amounts of land. This could interfere with efforts to produce food for a growing population, putting additional strain on plant and animal species. Another study found that converting enough land to avoid 2 degrees Celsius of warming would have a greater impact on European bird biodiversity than a 4 degree Celsius increase due to climate change.
Numerous organizations, including the Trillion Trees Initiative, have also emphasized the potential of tree planting as a means of combating climate change. As part of such efforts, several regions and organizations provide landowners and businesses with the opportunity to buy and sell carbon offsets.
According to the report, replanting trees in previously forested areas has a number of advantages. However, they warn that planting trees in places where they do not naturally grow can have negative environmental consequences.
Growing trees on natural open grasslands can reduce stream flow and increase wildfire intensity. Because grasslands reflect more heat than forests, it may even contribute to global warming. Similarly, draining peatlands to plant trees may result in large amounts of greenhouse gases being released from these rich natural carbon sinks.
The report’s authors note that ensuring that these approaches reliably and without adverse effects remove greenhouse gases will necessitate careful analysis of the local context and conditions. The findings also highlight the importance of pursuing diverse approaches to carbon removal, such as direct air capture and the use of various types of minerals.
It is becoming increasingly clear that large amounts of greenhouse gases will have to be removed from the atmosphere in the coming decades. But we don’t yet know how to do it cheaply, effectively, or consistently, let alone at the scale required.
Article Author Gerluxe