Well, it is easy conceptually at least. While advanced “negative emissions technologies” (NETs) like carbon-absorbing towers and light-reflecting clouds are touted as solutions to mitigating climate change, the best approaches may actually be the simplest and most low-tech: planting trees and improving soil quality.
That is the conclusion of a recent Oxford study reported in The Atlantic:
Both techniques, said the report, are “no regrets.” They’ll help the atmosphere no matter what, they’re comparatively low-cost, and they carry little additional risk. Specifically, the two techniques it recommends are afforestation—planting trees where there were none before—and biochar—improving the soil by burying a layer of dense charcoal.
Between now and 2050, trees and charcoal are the “most promising” technologies out there, it said.
Charcoal refers specifically to the production of biochar, an ancient practice whereby agricultural waste (such as food scraps, decaying leaves, etc.) is smoldered and then covered by dirt. This not only makes the soil richer, but it helps dispose of a major source of CO2 while also eliminating the need to clear forest for more arable farmland.
As the article notes, these low-cost methods have a long and proven track record:
Forest management is one of the oldest ways that humans have shaped their environment. Before the arrival of Europeans, Native communities in the Americas had been burning forest fires for millenniato support the growth of desirable plants like blueberries and to manage ecosystems. British communities have long practiced coppicing, a tree-cutting technique that keeps forests full of younger trees.
In other words, humanity has been “geoengineering” with trees for a very long time. The authors of the Oxford report add that afforestation will need global support in order to be successful.
“It is clear that attaining negative emissions is in no sense an easier option than reducing current emissions,” it says (emphasis mine). “To remove CO2 on a comparable scale to the rate it is being emitted inevitably requires effort and infrastructure on a comparable scale to global energy or agricultural systems.”
It is interesting that the authors also cautioned against viewing NETs as a”deus ex machina that will ‘save the day,'” viewing them instead as just some of the many ways to avoid the worst of climate change still yet to come. That said, reforestation and soil enrichment alone will not solve the problem either; reducing emissions in the first place, in conjunction with these and other methods, is still our best bet.
This is confirmed by two recent reports by the National Research Council, an arm of the United States National Academies. As National Geographic reports:
An NRC committee of experts from across disciplines was asked by several U.S. government science and intelligence agencies to evaluate geoengineering proposals. The ideas range from anodyne (planting trees to capture CO₂) to potentially alarming (injecting sulfate particles or other aerosols into the atmosphere to reflect sunlight and cool the planet).
Committee members were blunt in their first recommendation: The world should focus first and foremost on curbing fossil fuel emissions rather than on any kind of geoengineering.
“I think it’s going to be easier and cheaper to avoid making a mess than it will be to make a mess and then try to clean it up later,” said committee member Ken Caldeira, a climate scientist at Stanford University’s Carnegie Institution for Science. “If we end up having to build a fix that’s on the scale of our energy system, why not just retool our energy system?
The first, CO₂ removal, the committee characterized as worthy and “almost inevitable.” The second, using aerosols or other means to reflect solar radiation, would be “irrational and irresponsible” if done as anything but a last-ditch effort to prevent a global famine or other emergency.
The Royal Society of the United Kingdom and the Intergovernmental Panel on Climate Change (IPCC) have similarly put an emphasis on reducing emissions first and foremost, with other strategies being auxiliary or complementary.
We know the solutions, and have ample resources and capital to draw upon — we just need the political and public will to make it all happen. If merely planting trees, enriching soil, and cutting back on carbon usage are enough to largely avert an existential threat to humanity, then the worsening of climate change is a damning condemnation of our species’ foolishness and shortsightedness.