• Otávio Santiago

The UN’s climate report highlights the dangers of natural solutions

A variety of researchers have highlighted the potential to leverage nature to combat climate change, by planting trees or growing crops to suck carbon dioxide out of the atmosphere.

But a bleak new report from the UN’s climate panel stresses that relying heavily on these approaches could present real risks as well.

The nearly 4,000-page analysis, released on Monday, warns that more than 3 billion people around the globe are “highly vulnerable” to climate change, and that extreme weather and other effects are already pushing human systems beyond their ability to adapt. Given the decades-long delay in shifting away from fossil fuels, the world must now rapidly eliminate emissions, adapt to the changes already underway, and remove billions of tons of the greenhouse gases driving climate change, researchers conclude. The UN climate panel previously found that limiting global warming to 1.5 ˚C could require pulling as much as 8 billion tons of carbon dioxide from the air annually by midcentury, using what’s known as bioenergy with carbon capture and storage, or BECCS.

This process taps into the natural ability of crops and other plants to consume the greenhouse gas as they grow. In turn, specially designed or retrofitted facilities can use these plants to produce electricity or fuels, while capturing and storing the resulting emissions. Only a handful of facilities are doing this today, though a growing number are in the works.

But the UN report warns that planting enough crops to remove significant levels of carbon dioxide will require vast amounts of land. That could conflict with efforts to produce food for a growing population and put additional strains on animal and plant species. One study noted that converting enough land to avoid 2 ˚C of warming might shift the range of a larger portion of European bird species than 4 ˚C of warming from climate change.

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