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carbon sequestration
How to Build a Climate Bomb
Starting and then stopping solar geoengineering would cause the warming that had been temporarily held in abeyance to show up quickly and with a vengeance.
Apr 10, 2024
A major effort to limit climate change could actually make the problem much worse. If that sounds maddeningly paradoxical, then welcome to the bizarre science-fiction world of solar geoengineering.
There are two main pathways for deliberately altering Earth systems (i.e., geoengineering) in order to reduce the severity of global warming: carbon dioxide removal and radiation shielding. The former pathway is widely discussed, though little progress is being made. Methods of removing carbon from the atmosphere are either biological (regenerating soil and planting trees) or mechanical (building machines to suck carbon dioxide out of the air). Generally, biological methods show far more promise. But, regardless of method, the problem of scale is daunting: As a result of decades of rising greenhouse gas emissions, there’s a hell of a lot of excess carbon that needs to be removed.
Hence the alternative pathway of radiation shielding or solar geoengineering. Why not cool the Earth by reducing the amount of sunlight warming it? By most calculations, this would be a cheaper and faster way out of the climate crisis than carbon removal. Again, there are diverging pathways. The two most frequently discussed are sending up high-altitude planes to disperse tiny reflective particles (this is known as stratospheric aerosol injection, or SAI), or building a space parasol to shield the planet from some of the sun’s rays.
What’s really needed to reduce climate risk is a coordinated effort to greatly shrink humanity’s overall energy usage and material consumption, along with massive investments in nature-based carbon removal.
Many people regard these as last-ditch, risky projects. However, the failure of humanity so far to reduce carbon emissions, plus a flurry of alarming recent studies about rapidly warming oceans, climate feedbacks, and tipping points, are leading some scientists and activists who previously dismissed solar geoengineering to now have second thoughts.
The first SAI pilot projects could start soon. But to achieve global cooling of, say, 1°C would require a fleet of planes hoisting and dispersing several million metric tons of particles high in the stratosphere. Forging international agreements for such a project and building the required infrastructure could take well over a decade. Constructing a space parasol would probably take even longer and be more expensive.
What could go wrong? Tinkering with the climate in one place could trigger droughts or mega-storms elsewhere. Only wealthy nations or corporations could undertake solar radiation geoengineering at the scale needed to achieve significant results, so there is at least the theoretical possibility of the technology being used in a subtle or overt form of global extortion. (Nice climate you’ve got there. You want it to stay that way? Pay up.) Also, fossil fuel industries and governments dependent on fossil fuel revenues could use geoengineering as an excuse to keep polluting.
But there’s one important risk that is discussed less frequently. If a global solar radiation management program were to start but then stop, then the warming that had been temporarily held in abeyance would show up quickly and with a vengeance. This is how a European Parliament briefing document from 2021 puts it:
Once started, solar geoengineering cannot be stopped. Assuming that carbon emissions continued, the artificial sunshade would mask increasing amounts of extra warming. If geoengineering ceased abruptly—due to sabotage, technical, or political reasons—temperatures would shoot up rapidly. This termination shock would be catastrophic for humans and ecosystems.
How Big of a Bomb Are We Talking About?
The word “catastrophic” in the text just quoted gives little indication of scale. A termination shock would be bad—but climate change is already bad. How awful might a geoengineering termination shock actually be? A couple of metaphors could prepare us to estimate the potential size of such a shock.
Think of climate change as a wildfire. An uncontrolled burn releases energy previously held in trees and grasses, adding it to the local environment in the form of heat. Similarly, by trapping solar radiation, greenhouse gases add energy in the form of heat to the global climate system (elsewhere, I have proposed calling the fossil-fueled industrial era “the Great Burning”).
In contrast, a sudden release of pent-up warming would metaphorically more closely resemble a bomb, whose explosion releases energy far faster.
The sudden release of just one year’s worth global warming energy would be the equivalent of nearly 1,000 times the energy yielded by exploding the world’s entire nuclear arsenal.
How much energy? Let’s run the numbers. First, we should settle on a unit of measure. Energy can be expressed in watt-hours or joules, but for our purposes it might be more fitting to use a measure typically reserved for describing the energy released by nuclear weapons—the megaton (Mt), which refers to the explosive energy of a million tons of TNT.
The energy transfer that’s causing climate change can be measured in megatons. A recent study found that the Earth’s oceans, which absorb most of the heat trapped by greenhouse gases, capture “the heat of five to six Hiroshima atom bombs per second.” The Hiroshima explosion was estimated at 15 kilotons of energy, so a little quick math tells us the oceans are absorbing at least one megaton of energy from global warming every 13 seconds or so.
The total firepower of all current nuclear weapons is estimated at 2,500 Mt. A bit more arithmetic tells us that’s about nine hours’ worth of global warming. So, the sudden release of just one year’s worth global warming energy would be the equivalent of nearly 1,000 times the energy yielded by exploding the world’s entire nuclear arsenal.
That’s a really, really big bomb.
I’m not saying that the effects of global warming would mirror the immediate effects of detonating the world’s nuclear arsenal 1,000 times over. But there would surely be horrendous consequences from the Earth having to absorb all that energy so fast.
If we continue spewing greenhouse gas emissions, we will be capturing the same amount of energy from the sun and heating the planet just as much, but more slowly and over a longer time (that’s the metaphorical wildfire). Adaptation to global warming at current rates will be extremely challenging for societies and ecosystems; in some cases, adaptation will probably fail, leading to casualties and collapse. The last thing we should be doing is speeding up the rate of change by building a climate bomb.
If we Start Geoengineering, How Likely Is an Unintended Termination?
Whether the risk of humanity’s failure to maintain a solar geoengineering program, once it has started, is seen as substantial or trivial depends partly on whether you view modern industrial civilization as inherently sustainable.
Most governments and economists see industrial civilization as here to stay. We may have a few problems to contend with, say the techno-optimists, but these can be solved; ultimately, technological progress is unstoppable.
However, researchers in the fields of ecology and systems science claim that our current global industrial system will necessarily be self-limiting over time, due to resource depletion and pollution. We can improve the efficiency of industrial processes up to a point, but increasingly they are limited by supplies of natural resources and availability of waste sinks. For wealthy modern societies, whose resource flows and waste streams are gargantuan by any historical measure, those natural limits are set to bite soon, and bite hard.
If world leaders continue to fail to mount that effort and make those investments, will they eventually turn to solar radiation geoengineering as an alternative solution, because it’s cheaper and doesn’t involve as much perceived sacrifice? We’d better hope not, because it would be an epically, apocalyptically horrible idea.
Rockets, satellites, and high-altitude planes are all fixtures of the early 21st century. They depend on mining, manufacturing, and transport systems that didn’t exist until the late 20th century, and that probably can’t be maintained for more than another few decades. The future will be all about simplification—whether by design or default.
So, to me, the failure of humanity to maintain a solar radiation geoengineering project, once it has started, is not a remote risk; rather, it’s the most likely thing that would happen.
Maybe I’m wrong about that. Perhaps there’s only a 10% risk of a geoengineering failure resulting in a sudden global warming rebound. But it’s a risk that would entail global heating of a speed and magnitude that would be both unprecedented and terrifying.
What’s really needed to reduce climate risk is a coordinated effort to greatly shrink humanity’s overall energy usage and material consumption, along with massive investments in nature-based carbon removal. If world leaders continue to fail to mount that effort and make those investments, will they eventually turn to solar radiation geoengineering as an alternative solution, because it’s cheaper and doesn’t involve as much perceived sacrifice? We’d better hope not, because it would be an epically, apocalyptically horrible idea.
Finally, here’s the good news. Solar geoengineering is still in the category of bad things that aren’t happening, but might. This means that, with more public awareness, it could be prevented.
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Cerrado Deforestation Called a 'Stain' on Lula's Environmental Record
While Amazon deforestation fell nearly 50% in 2023, it rose by almost 43% in the unique and important grassland.
Jan 15, 2024
Deforestation in Brazil's vital Cerrado region jumped by 43% in 2023 compared to 2022, the highest level since deforestation measurements began in 2019.
The news, released by Brazil's National Institute for Space Research this month, came as deforestation in the more widely known Amazon rainforest fell by nearly 50% in 2023. President Luiz Inácio Lula da Silva has promised to end deforestation by 2030, but environmental campaigners say agriculture in the Cerrado could undermine that goal.
"Lula's sacrifice of the Cerrado to beef and soy production is a major stain on his environmental credentials, and needs to be reversed and rectified urgently," Mighty Earth senior director Alex Wijeratna told the Financial Times. "The Cerrado savanna is being massively overlooked in Brazil and by the global community."
Brazil's Cerrado is the most biodiverse grassland ecosystem in the world, hosting 5% of all plant and animal species, according to WWF. The roughly 200 mammal species that live there include giant anteaters and armadillos. It is also home to 860 species of birds, 1,200 species of fish, and 90 million species of insects. Almost half of its more than 11,000 species of plants only grow there and are important to the survival and culture of local communities.
Beyond providing biodiversity, the savanna is important for Brazil's water system. It provides the spring for six of the country's 12 most important hydrological regions. Globally, it, like the Amazon, is an important carbon sink. It is home to shorter trees with vast underground root systems that may keep as many as 118 tons of carbon per acre out of the atmosphere.
"If destruction of the Cerrado is not stopped, the global commitment to cap global warming at 1.5°C will become unattainable," WWF said.
"Unlike the Amazon where prevention can be done via law enforcement, in the Cerrado incentives have to be created for landowners to give up their right to deforest."
Despite its ecological importance, the Cerrado has not received the same global attention as the Amazon, and experts say this has hampered conservation efforts.
"Internationally, the Cerrado is not very well known. If it had a name like the Amazon, we would have more (public) policies that benefit the conservation of the biome," Ane Alencar, science director at the Amazon Environmental Research Institute (APIM), toldThe Associated Press.
Alencar said the Cerrado is currently harder to protect because of the laws in place. In the Amazon, Lula's government had success by cracking down on illegal logging, ranching, and mining, the Financial Times explained.
But in the Cerrado, most deforestation occurs on private land, and a significant amount of it is currently legal, Alencar explained. While landowners in the Amazon may only clear 20% of the trees on their property, landowners in the Cerrado may clear 65% to 80%. The Amazon also has more protected nature reserves and Indigenous territories.
"In many cases, the suppression of native vegetation is allowed by the forest code. So, unlike the Amazon where prevention can be done via law enforcement, in the Cerrado incentives have to be created for landowners to give up their right to deforest," APIM executive director André Guimarães told the Financial Times.
Deforestation in the Amazon soared to its highest level in 12 years under right-wing Brazilian President Jair Bolsonaro, according to BBC News. Bolsnaro favored extractive industries over conservation and Indigenous rights, while Lula has promised to safeguard the forest. In 2023, 5,153 square kilometers of forest were lost, compared to 10,278 square kilometers in 2022. Officials said it was the lowest deforestation rate in five years.
In the Cerrado, meanwhile, 7,852 square kilometers of vegetation were lost in 2023, AP reported.
"We saw some important victories on the environment in 2023. The significant reduction in deforestation in the Amazon was a highlight," Mariana Napolitano of WWF-Brasil told Agence France-Presse.
"But unfortunately we aren't seeing the same trend in the Cerrado... That is harming the biome and the extremely important ecosystem services it provides," Napolitano added. "And we saw the impact at the end of the year, with extremely high temperatures."
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Biden Move on Old-Growth Forests Called 'Important Milestone'
One campaigner said it is "a meaningful step towards averting climate catastrophe, safeguarding vulnerable ecosystems, and fulfilling President Biden's commitment to preserve old-growth and mature trees."
Dec 19, 2023
Conservationists on Tuesday applauded the Biden administration's first-of-its-kind proposal to conserve and restore old-growth trees across national forests and grasslands with limits on logging, "so nature can continue to be a key climate solution."
The plan would protect the nation's most ancient forests from commercial logging on approximately 25 million acres of public lands, though it would allow some cutting of trees under stricter conditions than currently exist.
The United States is a top contributor to planet-heating pollution, largely from fossil fuels. White House Council on Environmental Quality Chair Brenda Mallory noted in a statement that "our forests absorb carbon dioxide equivalent to more than 10% of our nation's annual greenhouse gas emissions."
The proposal to amend all 128 forest land management plans in line with an executive order issued last year by President Joe Biden comes from the U.S. Department of Agriculture (USDA). Agriculture Secretary Tom Vilsack said that "climate change is presenting new threats like historic droughts and catastrophic wildfire. This clear direction will help our old-growth forests thrive across our shared landscape."
Many campaigners agreed—including Earthjustice's Blaine Miller-McFeeley, who praised the proposal "an important milestone," and Ellen Montgomery of Environment America, who called it "unprecedented."
"Protecting our old-growth trees from logging is an important first step to ensure these giants continue to store vast amounts of carbon, but other older forests also need protection."
Sierra Club forests campaign manager Alex Craven stressed that "our ancient forests are some of the most powerful resources we have for taking on the climate crisis and preserving ecosystems."
"We are pleased to see that the Biden administration continues to embrace forest conservation as the critical opportunity that it is," he added. "This amendment is a meaningful step towards averting climate catastrophe, safeguarding vulnerable ecosystems, and fulfilling President Biden's commitment to preserve old-growth and mature trees across federal lands."
Oregon Wild's Lauren Anderson declared that "President Biden is taking a major step forward in protecting these national treasures."
While welcoming the administration's plan, conservationists also pushed for further action from the USDA's Forest Service—which, along with the U.S. Department of the Interior's Bureau of Land Management, manages approximately 32 million acres of old-growth forests and 80 million acres of mature forests nationwide.
"Protecting our old-growth trees from logging is an important first step to ensure these giants continue to store vast amounts of carbon, but other older forests also need protection," explained Randi Spivak of the Center for Biological Diversity. "To fulfill President Biden's executive order and address the magnitude of the climate crisis, the Forest Service also needs to protect our mature forests, which if allowed to grow will become the old growth of tomorrow."
Standing Trees executive director Zack Porter pointed out that "more than 99.9% of old-growth forests in New England have already been cut down."
"For the climate and biodiversity, the Forest Service must put an end to destructive mature forest logging that prevents the recovery and expansion of old-growth forests across the U.S.," he said. "We are buoyed by today's announcement, and remain optimistic that the Forest Service will take further action to secure protections for America's future old-growth forests."
The Washington Post reported that "some environmental advocates also questioned whether the policy will last, as a future administration could easily undo it," considering that the changes "won't be finalized until the agency has completed an environmental impact statement, which it expects to finish in early 2025."
Campaigners have also long argued that protecting the carbon storage capacity of U.S. forests cannot be considered a real climate solution unless paired with other key actions. As Food & Water Watch's Thomas Meyer put it last year, "Protecting forests without addressing the root cause of the climate crisis, namely the continued extraction and burning of fossil fuels, will do very little to slow global warming."
The global phaseout of fossil fuels was a primary focus of the recent United Nations climate talks, which wrapped up in Dubai earlier this month with a deal that scientists decried as "a tragedy for the planet" because it failed to explicitly demand ending the era of oil, gas, and coal. The United States was represented at COP28 by John Kerry, Biden's climate envoy, as the president skipped the summit.
Biden, who is seeking reelection next year, has been blasted by experts, frontline communities, and younger voters for refusing to declare a national climate emergency, continuing fossil fuel lease sales for public lands and waters, enabling the Willow oil project and Mountain Valley Pipeline, and supporting the expansion of liquefied natural gas exports.
For his part, former President Donald Trump, the leading contender for the Republican Party's nomination, has vowed to "drill, drill, drill" if he wins back the White House in 2024.
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