The year the forest-protecting constitution was enacted was the same year that the new king, a twenty-eight-year-old reformer, was coronated. This was no ordinary coronation: the elder king had announced the transition of the monarchy into a democracy. People had come by truck, motorbike and yak from all regions of the country to see the former king place the Raven Crown on the head of his son. The ceremony was held on November 6, 2008, a date deemed auspicious by three enlightened astrologers. A Thursday: the eighth day of the ninth month of the earth male rat year.
I was visiting the country then, and sharing in the nation’s jubilant mood. The day before, Obama had claimed the US election. I was glued to the blurry BBC coverage, guiltily monopolizing the television of the Bhutanese family whose farmhouse I was staying in. Occasionally, an eighteen-year-old boy named Singye would join me in watching the coverage. We sat upon carpets in the bare room and drank tea while I tried to explain what was going on with all the revelers in the streets of Chicago: a quarter of a million Americans, or more than a third of Bhutan’s population, turned out to celebrate.
“We have a new leader right now, too.”
“What’s his name?”
“Barack Obama.”
“Is he married?”
“Yes, with two children.” Singye nodded.
In Bhutan’s capital, Thimphu, they celebrated their new leader for three days: solemn ceremonies, concerts with traditional dance, archery. In honor of the coronation, all mobile phone communications were shut down during the day. The streets were lined with Buddhist flags: bright red, yellow, blue, green, white. At night, the trees and buildings were festooned with strings of rainbow light.
In my conversations, I had been surprised to learn that people were excited about the transition to the young Dragon King, but often less enthused about the transition to democracy. People adored the monarchy. They’d seen conflict and corruption while watching elections in neighboring India, and they weren’t sure if they wanted their country to go that route. I observed the festivities from a hill, across the river from the seventeenth-century fortress in Thimphu where the coronation ceremony was taking place. While watching the crowds gather, I ran into another foreigner—a development professional. I told him what I’d been hearing about this governmental transition, about the wariness toward democracy. He responded with an anecdote about working in Vietnam, a one-party state that could implement policy shifts quickly. One day, the government had decided that everyone needed helmets for motorcycles, and the next day, everyone had them. “Like that,” he said, snapping his fingers.
Bhutan is a standout example of how even in a democracy, a carbon-negative target can be achieved. It doesn’t necessarily require autocratic fiat or loving decree to make these land-use decisions. Of course, the practicalities of scaling up forest management and carbon-negative land use beyond a small, mountainous, sparsely developed country prompt the question: What kind of government could achieve this goal? To sequester one gigaton of carbon dioxide, one would have to afforest 70 to 90 million hectares, or a land area about twice the size of California.19 Now, again, current emissions are forty gigatons of carbon dioxide. So that’s a tremendous effort just to put away one gigaton. A few gigatons are certainly doable, since there’s a lot of farmland that’s been abandoned because of low productivity; one conservative estimate put the acreage at around the size of India.20 Scientists calculate that there are large areas of land available for reforestation—from 500 million hectares in bottom-up estimates, to between 1 and 3 billion hectares in modeled estimates of nonagricultural land broadly.21
But how can the transition be orchestrated, and how many times can that feat be repeated? A finite number of times. Consider figures like those outlined in “Alternative Pathways to the 1.5°C Target Reduce the Need for Negative Emission Technologies,” a helpful analysis by a European group of modelers (reported eagerly in the environmental press as “World Can Limit Warming to 1.5°C ‘without BECCS.’”)22 How did the modelers do it? For starters, they assumed capture of 400 gigatons by reforestation. But here’s the assumption you have to dig out of the details: in their scenario, agricultural efficiency increases, and massive areas of cropland and grazing land are converted to forests. Next, this storyline “assumes a technological breakthrough and mainstream acceptance of cultured meat, starting in 2035 … We assume that by 2050, 80 percent of meat and eggs (but not fish and seafood) are replaced by cultivated meat, which is grown directly from corn and small amounts of soy.”23
Indeed, if we switch to “cultivated meat,” grown from cells in vats, or just to plant-based meat, then we can plant trees on the vast swaths of land that are currently being grazed for meat production. But at this point, we’re not just talking about an afforestation project. We’re talking about cultural and behavioral change in countries who value meat, including getting them to accept something as new and potentially weird as lab-grown meat; about telling people who just gained the economic capacity to have meat that they should switch to something else; about defanging a powerful industry lobby; about telling scores of pastoralists that they need to adopt different livelihoods. This is more than “afforestation” in a simple sense. It’s a social project, enrolling education, public health, and more. Afforestation on this scale is basically geoengineering. Whether that dramatic transformation is easier, better, or more desirable than all the other approaches to removing carbon should be a vibrant matter of debate. But it’s not as simple as planting a seed in the earth.
Talk of forest creation begs the question: What exactly is a “forest”? There are things that look like forests, but they may not be carbon rich. A recent study in Science showed that Europe has been considerably afforested since 1750—with an increase of 10 percent over this period (most of it from 1850 to present). During this transition, 85 percent of the forests were put into management. Yet two and a half centuries of managing these forests has not contributed to cooling. Instead, converting deciduous forests into coniferous forests changed the albedo (the proportion of the light reflected by the earth’s surface), canopy roughness, and evapotranspiration from the land, which warmed things up. Europe’s forests accumulated a carbon debt of 3.1 gigatons over this time, as the extraction of wood released carbon that was stored in biomass, litter, deadwood, and soil carbon.24 Most biomass carbon is in the woody stems and roots of old trees, and primary forests store 30 to 70 percent more carbon than commercially logged or plantation forests. It takes hundreds of years to grow these carbon stocks to their natural capacity.25 There’s also a big difference between tropical and boreal forests, and the net climate effect of increasing boreal forest is unclear.26 Moreover, scientists have been sobered to find that trees can emit methane and volatile organic compounds, which could offset their cooling effects.27 Complicating it further, afforestation schemes need to be “climate smart” by accounting for projected climate impacts, including extreme storm events or outbreaks of forest diseases and pests. Forests may be a risky place to bet on for carbon storage, because in the event of wildfires or die-offs, the carbon could be lost.
Yet from Bhutan to the Sahel’s so-called “Great Green Wall” to China’s national reforestation project, aspirations for afforestation and reforestation are vast. Emerging technologies, like aerial planting of seedlings via drones, may aid states and organizations in their efforts. Theoretically, governments can play a large role in this. Much forestland is within the purview of governments: one-third of Latin American forests, about two-thirds in Asia, and virtually the entire area of forests in Africa.28 However, one problem with making calculations around the ability of countries to command afforestation or reforestation is the assumption that developing countries have full control over the lands and actors within their borders, notes geographer Jon Unruh. He points to the problems of enforcement, deep and long-lasting resistance to and suspicion of land-related policies, corruption, and discrimination.29 Existing forest carbon schemes such as REDD+ (Reducing Emissions fro
m Deforestation and Forest Degradation, the program under the UN Framework Convention on Climate Change) have run into a host of documented problems: the inadequacy of certification schemes to protect livelihoods and biodiversity when pursuing climate goals,30 the ways in which “carbon colonialism” via plantation forestry amounts to neoliberal land grabs,31 and many others. On the other hand, research has also shown how agricultural intensification, land use zoning, forest protection, increased reliance on imported food and wood products, and foreign capital investments can all work together in managing land use transitions.32 What’s clear is that it’s not useful to treat afforestation as something that happens “over there,” in the forest. Rather, it’s a complex social project that touches all of us—at the very least, through what we choose to eat every day. That juicy hamburger could instead be a tree storing carbon: modeled pathways for keeping warming to 1.5°C assume that it will become one.
Blue Carbon
Carbon stored in peatlands, mangroves, tidal marshes, and seagrasses is collectively known as “blue carbon.” These areas are thought to be hot spots for storing carbon, and so one of the best things for the climate would be to stop destroying wetlands. One-third of the world’s mangrove, seagrass, and salt marsh areas have been decimated over the past several decades.33 They are being degraded at devastating rates—in some instances, up to four times that of rain-forests.34 Between 2 and 7 percent of blue carbon sinks are being lost annually, which is a crazy rate of decline. Protecting these ecosystems could contribute powerfully to mitigation. One UN report estimated that doing so could amount to 10 percent of the reductions needed to keep CO2 concentrations below 450 parts per million.35 Seagrass meadows are particularly impressive: they can sequester carbon for millennia. Sediments in healthy coastal ecosystems can continue to accrete carbon vertically as sea levels rise. This means they can keep building up carbon, unlike the terrestrial carbon sinks, which become saturated in a few decades.
Enhancement of blue carbon via wetland restoration and protection seems like one of the carbon removal approaches with the fewest drawbacks. It’s something that can go alongside existing restoration and coastal adaptation / shoreline protection projects. For example, biochar and other carbon-rich materials could be used in these projects to sequester even more carbon. Despite its potential importance, blue carbon has scarcely been addressed in the literature on “climate engineering,” at least up until the 2018 National Academies report put it on the research agenda for “negative emissions.” I asked marine geochemist Sophia Johannessen about this apparent omission. She explained that it’s a new field: “These papers started to appear in about 2001, and the field has expanded rapidly since them.” Johannessen is actually at the center of a lively scientific debate on this topic, in the wake of a 2016 paper she published with fellow Fisheries and Oceans Canada colleague Robie Macdonald: “Geoengineering with Seagrasses: Is Credit Due where Credit Is Given?”36 In it, they argue that while seagrasses are reported to account for up to 18 percent of the carbon burial in the world’s oceans, the accounting is wrong because it doesn’t address how carbon is deposited in marine sediment. In fact, estimates may be off by 11- to 3,000-fold. I asked her what accounts for the incredible variance in assessments, and she speculated that it might be disciplinary boundaries between two communities of research. “The people who are publishing these papers, saying that there’s a huge sequestration potential in seagrasses, haven’t been working in marine sediment geochemistry,” she replied. “They know about the biology of seagrasses, but they don’t really understand how sediments process and sequester carbon.”
Biologists are naturally intrigued by sequestration in seagrass meadows because seagrasses are crucial habitat for juvenile fish. But these ecosystems, being right at the coastlines, are under threat from urban development. Carbon sequestration would add a compelling reason to protect seagrasses. Yet to a marine geochemist, carbon sequestration in seagrass seems elusive. First of all, most of the carbon that’s sequestered in coastal sediments isn’t sequestered where seagrass grows. Organic carbon sticks best to very fine particles. But seagrasses generally grow in coarser sediment, like sand—so the places where the seagrass is growing aren’t really the places where carbon tends to build up. Another issue is that a lot of global estimates of carbon sequestration in seagrass meadows are based on measurements of one specific type of seagrass that grows in beds in the Mediterranean and Southern Australia, Posidonia. It has extremely long root mattes that extend for meters into the ocean floor. These root mattes are not the norm for seagrasses generally, yet measurements from Posidonia haven been extrapolated throughout the world.
Coastal sediments, root mattes: this all sounds pretty obscure. But the stakes for getting it right are high, because the first international protocols are now emerging around the voluntary market for carbon burial via seagrass. Sequestration in seagrass meadows could therefore be used to offset emissions elsewhere. “But if the seagrasses really aren’t actually storing as much as people think, and credits for planting seagrasses are used to offset emissions elsewhere, then the net effect could be an increase of carbon emissions into the atmosphere—just the opposite of what carbon credits are supposed to achieve. So it’s a really important topic, even though it sounds boringly technical.” Johannessen explains, summarizing the short story: Seagrasses are important for habitat and protecting coastlines. “Some people have said that seagrasses also bury a lot of organic carbon, and that we should be able to claim carbon credits for protecting or restoring them. Marine geochemists reply that the current accounting methods are wrong, and the estimates are far too high. But there is methodology that can be used so that people actually could assess carbon storage in seagrass meadows properly, and there is a potential for it to be used for claiming carbon credits in the future.”
On one hand, it’s disheartening to see how information about carbon removal can fall into this void between disciplines and lead to these technical mistakes in calculating global potential—we could probably find similar illustrative examples for every other carbon removal technique, too. On the other hand, it’s promising to see the scientific process engaged and self-correcting, lending hope to the idea that maybe we will have better estimates to guide us in the future. Yet even if we did have perfect knowledge about how much carbon all these practices could sequester, would people act on it?
Will natural carbon removal fulfill our hopes?
These regenerative, land-based approaches to carbon sequestration are exciting in part because people bring such love, care, and devotion to them. Through these conversations about regeneration and natural climate solutions, people are developing a broader vision for how to live with the earth in the future.
This capacity to envision alternate futures is precisely what is needed. It is invigorating a stale climate politics with grassroots energy. And yet, in terms of the capacity of natural climate solutions to not only mitigate but reverse climate change, there are three sobering realities that must be kept in mind.
The first is the difference between one-off removal and continual removal. Both large-scale afforestation and soil carbon sequestration face this issue of being techniques whose storage capacity levels off over time. Second, many natural climate solutions aren’t permanent—they require maintenance and could be reversed by future decisions, as well as by climate change itself. For example, some research on conservation tillage shows that it may only increase soil carbon to a depth of ten centimeters. Because this thin layer is very vulnerable to changes in management, agricultural practices may not sustain surface soil carbon over the centuries or millennia for which climate policies must be designed.37 However, this maintenance requirement should not be thought of simply as a burden or liability. “Though premised on a logic of escape and exit, the marking of buried materials is also tied to the marking of sites of ongoing obligation,” write Kearnes and Rickards.38 These types of obligation and care are of a very different logic than our socie
ty has been running on. But care and the intention to maintain carbon can only go so far: if left unchecked, climate change could reverse terrestrial carbon sinks by mid century.39 Wind and rain will erode soil into the ocean; fires will burn down forests. In this sense, the efficacy of the solutions is vulnerable to the problem itself.
A third reality concerns the scale of these measures’ results compared with the scale of emissions. Remember, current emissions are on the order of forty gigatons of CO2 per year, or fifty gigatons of CO2 equivalent when you count other greenhouse gases. Afforestation, soil carbon, and biochar, at the extremes of their socio-technical potential, could remove perhaps ten to twenty gigatons of CO2 equivalent per year of that (as per the 2017 UN Environment Programme’s Emissions Gap Report). But this would be a tremendous work of social and industrial transformation. This highlights, first, the need to stop emitting. It’s impossible for these techniques to make up for our current levels of carbon emissions. And this peak in emissions needs to happen right away. For even if you view the problem on a longer time frame, say 200 or 300 years, those natural sinks will be sequestering their ten gigatons CO2 equivalent per year for, say, 50 years—then they will be full.
Try this thought experiment. Imagine that emissions flatline in 2020; the world puts in a strong effort to hold them steady, but it doesn’t manage to start decreasing them until 2030. It’s plausible that it would take ten years to start a worldwide decrease, right? But ten years steady at 50 Gt CO2eq—and there goes another 500 GtCO2eq into the atmosphere. That one decade would cancel out the 500 GtCO2eq the soils and forests could sequester over the next fifty years (sequestered at an extreme amount of effort and coordination among people around the whole world). Plateauing emissions for a decade before starting to bring them down might not sound that bad—the world would probably celebrate that triumph—but it would take fifty years of Herculean effort in enhancing these natural sinks just to make up for that decade alone of flat emissions. Then, the sinks would be maxed out in terms of additional removals. But we’d still have to maintain the storage, or we’d risk releasing the carbon again. Moreover, there wouldn’t be enough sink capacity later on in the century to make up for small amounts of continued emissions from some hard-to-mitigate sectors, like shipping, aviation, steel, or rice production.
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