One hundred miles beneath us lies the planet’s molten, roiling interior; one hundred miles above us, far beyond the protection of the clouds, the upper atmosphere basks in the brilliant white glow of the Sun. Everything in between, wrote the scientist and inventor James Lovelock, is Gaia: the “dynamic physiological system that has kept our planet fit for life for over three billion years”.
Gaia, in Lovelock’s conception, is the air we breathe, the water we drink, the soil we tread, the fruits we pluck from a tree. These are not discrete phenomena, according to the “Gaia hypothesis”, but different aspects of an interrelated whole. Mother Earth fills our lungs with air, our hands with food, and our river beds with water.
But what Gaia gives, warned Lovelock, she can take away. With “breathtaking insolence”, he wrote, humans have cracked open Gaia’s stores of carbon, hitherto buried so as to keep oxygen at its proper level, and burnt them as fuel. We have “usurped Gaia’s authority and thwarted her obligation to keep the planet fit for life”. Gaia, whose maternal patience lasts only so long, “now threatens us with the ultimate punishment of extinction”. With oceanic temperatures rising, predicted Lovelock, algae will falter in their production of dimethyl sulphide, a gas that helps clouds to form. With fewer clouds to shield us, the planet will become hotter and hotter. Perhaps a more apt Greek reference than Gaia is Medea — a mother who kills her own children.
Lovelock’s rather apocalyptic prognostications, published in 2006, might not be to everyone’s taste. Fossil fuels, though flawed, have helped lift billions of people out of poverty. Climate change, though devastating, is not remotely likely to be the death of humanity. Over the coming decades, we can expect longer droughts, hotter heatwaves, and more frequent and intense storms. As more data arrives, though, it seems that the worst-case forecasts, those that include runaway warming scenarios, look less likely than they did when Lovelock advanced the Gaia hypothesis.
Yet who among us has no weakness for animism? Last week, scientists informed conference-goers in Prague that the progressive melting of the world’s glaciers — which could lose as much as half their total mass by the year 2100 — will expose the long-buried volcanoes of Antarctica and elsewhere, sealed for millennia under gargantuan layers of ice. It is tempting to imagine that Mother Earth is preparing to punish her errant children, or that we dwarves, to invoke J.R.R. Tolkien, have indeed delved too greedily and too deep, awakening shadow and flame. Lovelock’s hypothesis did not posit Gaia as encompassing the magmatic fury of our planet’s interior, but it should have.
“Global warming will expose the long-buried volcanoes of Antarctica and elsewhere, sealed for millennia under gargantuan layers of ice.”
Two decades later, environmentalists still contend that, facing the vengeance of Mother Earth, we should simply submit to her will. Reduce, reuse, recycle — but do not re-engineer that dynamic physiological system. There are no workarounds, they argue; we must leave the planet as we found it.
This well-meaning submissiveness has amounted, in some cases, to a taboo against interfering with nature — a taboo that is now butting up against the hard reality of climate change. It is true that the most pessimistic and Lovelockian forecasts now seem less likely to be realised. But what we could think of as the medium-bad forecasts, in which we heat the planet by more than 2°C, are near-certain to be vindicated. The denialists, who have long insisted that climate change is not real, are as deluded as the environmentalists who insist it will eradicate humanity.
Our planet’s inarguable warming has led some iconoclasts — thick-skinned scientists and even a couple of audacious entrepreneurs — to argue that we should break the taboo against meddling. It is past time, in this view, that we rejected the authority of Mother Earth.
There is one particular act of meddling that will, over the coming years, prompt particular acrimony and vituperation. The act is “stratospheric aerosol injection”, by which we release a balloon filled with sulphur dioxide, a gas whose particles are reflective. The balloon, if it also contains helium, will rise — and when it pops, it will scatter those reflective particles. If the balloon, by that point, has soared above the clouds and into the upper atmosphere, then those particles will reflect the Sun’s brilliant white light back into space. And for every photon deflected back into the darkness, the Earth forgoes a quantum of warmth. Stratospheric aerosol injection, therefore, might seem to be a useful method for a species that is coming to regret its overheating of its home. Tiny amounts of sulphur dioxide can offset the heating effect of one’s annual carbon footprint. A sustained, large-scale operation, the argument goes, could do the same for humanity.
Environmentalists, who might putatively be in favour of the mitigation of global warming, call the method dangerous and its practitioners charlatans. Understandably, they see such schemes as entailing a failure to address the root causes of global warming, and a failure to address related problems such as air pollution. They also warn that the practice could change weather patterns and, if things go very badly, cause acid rain. More profoundly, many people feel intuitively that planetary systems should be sacrosanct, that to meddle with them would be tantamount to “playing God”.
Stratospheric aerosol injection is therefore the forbidden fruit in the garden of climate intervention. So far, only a very small number of people have dabbled in this dark art. Among them are the two co-founders of a start-up, Make Sunsets, that sends up balloons on behalf of customers. “We should not be the ones doing this!”, one of the start-up’s two founders told me last year, when I was writing a book on humanity’s efforts to avoid catastrophe. Make Sunsets’ operation resembles some of the more chaotic scenes from the TV series Breaking Bad: two rascals taking an RV to the wilderness in order to cook up something that many observers would view as utterly reprehensible.
But it is not just these two climate cowboys who are interested in the dark arts. The US government, for instance, has funded research into solar geoengineering, which encompasses methods such as making clouds more reflective. (Since then, the US Environmental Protection Agency has let it be known that it is willing to crush the Make Sunsets operation if it gets much bigger.) ARIA, which is a British government agency best thought of as a moonshot factory, has its own solar geoengineering programme, one that was derided in The Guardian as a “dangerous distraction from the work that needs to be done to achieve net-zero carbon dioxide emissions”. Leftist environmentalists typically prefer degrowth, irrespective of the damage it would do to global prosperity, to technical fixes.
Yet, as Britain is discovering, the race to Net Zero is a painful hobble. The project depends on political capital that elites are burning unsustainably fast. Voters are concerned about the climate, but they are also concerned about high energy costs and the economic stagnation that these high energy costs have contributed to. Given these circumstances, there is a good chance that, faced with an inexorably heating planet, some governments will — within a few years, and for better or worse — attempt to mount a serious solar geoengineering operation.
The existing operations, small and exploratory programmes that they are, do not amount to our species playing God. But decades of burning fossil fuels amounts, in its own way, to geoengineering. As a futurist scientist, Anders Sandberg, once said to me of the climate: “If you break it, you bought it.”
But the purchase comes with catches, of which one is the increasing public paranoia about weather intervention. When heavy rainfall caused lethal flooding in Texas this month, conspiracy theorists blamed foreign interference and vandalised weather monitoring equipment. Geoengineering is a Pandora’s box: not only environmentally, but also socio-politically.
Yet some scientists dream of even more muscular interventions. Should Gaia punish us by unsealing a horde of volcanoes, we will have even more reason to learn to tame their kind. We must learn, now or later, to prevent the kind of mega-eruptions that, at several times in the Earth’s history, have caused massive loss of life worldwide. Around 74,000 years ago, for instance, the eruption of the Toba supervolcano, in what is now Indonesia, caused so much atmospheric smog — as stratospheric aerosol injection would, but involving many orders of magnitude more material — that it has been accused of wiping out almost every living human. Volcanic winter, as this phenomenon is called, kills first the plants that can no longer photosynthesise, and then the animals that can no longer eat the plants.
The lethality of the Toba eruption has been contested, but we can say with confidence that severe volcanic events, those that come around every 50,000 to 100,000 years, would result in a world much like the one that followed the catastrophic arrival of Chicxulub, the asteroid that eradicated the dinosaurs. Relatively few of them would have been killed by the collision. Such was the amount of matter lofted into the atmosphere that most of them would have perished in the gloom that followed. The fossil record tells an eerie tale of an abundant planet transformed into one that was cold, dank and ruled by fungi.
It was with these events in mind that, 10 years ago, some researchers at the Nasa Jet Propulsion Laboratory suggested it might be possible to defuse a supervolcano. We would do so by extracting geothermal heat from it for millennia, thus wicking away the energy that would otherwise have found expression in an eruption. The paper remains a source of exasperation for geologists with even the most moderate streak of realism. The engineering challenge, I was told in 2024 by a beleaguered employee of the Yellowstone Volcano Observatory, is “just beyond description”: centuries of work, in very dangerous conditions, on a scale far larger than anything ever attempted in geothermal engineering.
Sandberg, the futurist who made the quip about humanity having to buy the climate, is one of the few scientists to have made a serious case for volcano geoengineering. Super-eruptions occur only very infrequently, but they occur all the same. In a paper published in 2023, Sandberg and his two co-authors gently point out that there are precedents for directly manipulating natural hazards, be they avalanches, forest fires, floods, landslides, or even, as of 2022, asteroids. They also refer to the handful of attempts in the 20th century to redirect dangerous flows of lava. These redirections were well-intentioned, although there were some who proposed to use volcanoes offensively. Reginald Purbrick, a wartime British MP, was keen on the idea of bombing Vesuvius so as to trigger an eruption. Similarly, it was suggested to President Roosevelt that the same might be done to Mount Fuji in order to “convince the mass of Japanese that their gods were angry with them”. Those dangerous schemes were never realised, but it is notable that they were even mooted. Perhaps it would not be wholly for the best if humanity became better able to direct the behaviour of volcanoes.
Lovelock, who died in 2022, was wrong about the character of Gaia. In some ways, as he identified, our world is exquisitely suitable for us. In other ways, though, it is irrevocably hostile. It is comforting to imagine that we are a foetus in the womb of Mother Earth, but the reality is harsher.
Addressing that harshness will create new and complex problems. Stratospheric aerosol injection, like cloud-seeding, will provoke rancour and paranoia. The engineering challenges will be much less arduous than the problem of fairly coordinating across different countries and interest groups. It is much likelier that geoengineering, of the climate and beyond, is undertaken without unanimous global consent than with it. Such projects will therefore violate two further taboos: one being democratic consent, the other being the principle that life-saving interventions must “first, do no harm”. These taboos should not be lightly broken. It is quite possible that, in a quest to avert a bigger eruption, we will incur smaller eruptions, affecting people who never agreed to the project.
For now, the idea of volcano geoengineering is fanciful. And so too is the idea of an imminent supervolcano eruption. But, in the long term, these events could pose a direr threat than climate change. One need only to consider a dinosaur fossil to be reminded of the peril of a darkened planet. It is true that Gaia is a beneficent Mother Earth as well as a callous Medea. But a child is only a child for so long.
