The world is hurtling toward catastrophic temperatures—and governments show no sign of restraint. Scientists are now more seriously considering the option of geoengineering—using tech to cool down the world. Is this possible—more importantly, is this wise?
A quick intro to geoengineering
The problem with our planet—or rather humans on our planet—is that we’re producing too much carbon dioxide. This means lots of sunlight comes in—and then gets trapped in our atmosphere. Hence, the planet keeps getting hotter and hotter. There are two possible ways to hack your way out of this problem:
Carbon dioxide removal (CDR): This fixes the problem by sucking carbon dioxide out of the air. This can involve growing certain kinds of trees or vegetation. Or machines that perform ‘direct air capture’: “These machines suck in air, pass it over membranes to remove the carbon dioxide, and pump it underground, locking it away forever.”
Solar radiation management (SRM): This covers a variety of technologies that reflect more of the sunlight away from earth—either by spraying chemicals into the atmosphere or even launching giant umbrellas into space.
As Wired elegantly puts it:
Carbon removal is like taking an antiviral, which helps your immune system banish the virus from your body; deleting carbon from the atmosphere similarly targets the root cause of the climate change problem. On the other hand, solar radiation management is more like taking an aspirin to reduce the fever the flu is causing. It doesn’t obliterate the problem-causing agent, and only treats symptoms.
Point to note: In this Big Story, we’re going to focus on solar radiation management. But there is more on carbon capture in the reading list.
The rise of solar radiation management
Origin story: Geoengineering began as a form of warfare back in the late 60s:
Between 1967-1972, Operation Popeye saw 2600 aircraft flying over Vietnam, carrying chemicals such as silver iodide. These chemicals can trigger rainfall and the U.S. hoped that prolonging Vietnam’s monsoon season would obstruct the Viet Cong’s movements.
It was shunned for decades for that reason. Later, environmental groups and politicians remained highly resistant to SRM—since it advocated more of what got us in trouble in the first place: Messing with Earth’s climate.
Why SRM; why now: The planet is warmer by 1.2°C. And it has become increasingly clear that we’re well on our way to a rise of at least 1.5°C—which will trigger catastrophic floods, droughts, wildfires and rising sea levels. Despite increasingly urgent warnings, governments have shown little appetite for the hard choices required to cut emissions—and meet climate targets.
This has weakened the ‘moral hazard’ argument against geoengineering—the worry that focusing on a quick technological fix will fatally undermine efforts to actually cut emissions. If Plans A through E shows no sign of working, then it may be time to at least consider that ‘last resort’ Plan F.
The tech billionaire effect: Geoengineering also reflects the mindset of the richest men on the planet—who believe technology can solve pretty much everything. They are also heavily invested in the status quo. Cutting emissions inevitably requires making radical changes in how people live—which isn’t what people like Bill Gates or Jeff Bezos want:
In your experience, things have worked out really well, so therefore the thing we’ve got going right now is probably pretty good. But also this climate change stuff is definitively not-good. What to do? Solar geoengineering can seem like an answer to that question… [T]he idea is comforting, a reassurance that there really is a quick fix for climate change, that we can just try it out, roll the atmospheric dice on some neat tech-fix, and then get on with doing things basically the same way we’ve been doing them up until now.
SRM option #1: Sulphur seeding
This is all about deflecting more sunshine away from the planet—which could help it cool down by at least 1.5°C. In other words, an idea that seems more alluring with every scorching minute—and has the greatest support from those tech billionaires. The most popular among these involves injecting sulphur into the atmosphere.
How it works: The technology is inspired by what we have observed in nature—when volcanoes erupt. In June 1991, Mount Pinatubo volcano sent ash clouds 25 miles high into the atmosphere above the Philippines. The ash cloud dimmed the sun—and temporarily cooled the world as much as 0.6°C over the next two years. The tragedy killed 900 people but also piqued scientific interest in a sulphur-based solution—which is now the most popular:
The idea is to inject sulphur dioxide—or perhaps other chemicals such as calcium carbonate or powders made of aluminium or diamonds—not into the troposphere, but the stratosphere, which begins up to 20 km above the surface. Such high-flying particles would end up distributed more widely than those from ships or volcanoes, and would hang around for longer. That means much less would be required for a given level of planetary cooling.
Data point to note: Some researchers estimate it will require injecting 2 million tonnes of sulphur—every year—to bring the temperature down by 1°C. In comparison, Mount Pinatubo sent 15 million tonnes into the atmosphere in a single shot.
But, but, but: As seductive as that math may be, we really have no idea what will happen if we make such a drastic intervention in Earth’s climate. One environmentalist expert says:
It would cool the Earth and it would reduce some of the impacts of global warming, but it would also produce a lot of risks that could reduce precipitation, or could destroy the ozone layer and let ultraviolet radiation through.
And much like volcanoes, it may cool some parts of the world down—while making others hotter—even “cancelling the Indian monsoon.” Also: the sulphur may drill holes in the ozone layer—which would make for a saucepan/fire kind of situation.
Last not least: This isn’t a one-off solution: “It’s something you have to keep on doing, essentially forever, on human timescales.” Also: If a number of the countries involved pulled their funding or changed their mind, it would result in catastrophic consequences: “This termination risk may cause temperatures to rebound at astonishing rates to the levels they would have reached without geoengineering.” Some studies indicate that ending such a program would result in a 1°C increase each decade:
Plant and animal species have adapted to less severe temperature swings throughout Earth’s history, but nothing like this. The rapid heat rise would kill people and crops, and damage oceans. Particularly sensitive species, like amphibians, wouldn’t stand a chance. “Obviously, if you had a strong SRM program ongoing and then it suddenly stopped,” says [political scientist Tyler] Felgenhauer, “that would be catastrophic environmentally.”
SRM option #2: The giant parasol
In comparison to the hazards of sulphur, rocketing a giant umbrella into space seems a lot less risky. There are other variations on the theme: creating a shield made of “space bubbles” or anchoring a big solar shield on an asteroid. Here’s the basic concept:
The idea is to create a huge sunshade and send it to a far away point between the Earth and the sun to block a small but crucial amount of solar radiation, enough to counter global warming. Scientists have calculated that if just shy of 2% of the sun’s radiation is blocked, that would be enough to cool the planet by 1.5°C.
A small hitch: The sun shade will have to be about a million square miles—roughly the size of Argentina—to block the required amount of radiation. A single shade that size will weigh over 2 million tons—way too heavy to launch into space. So it would have to involve many smaller shades that look something like this:
But, but, but: There are a number of intrinsic problems in relying on any kind of umbrella in space:
A sunshade would be astronomically expensive and could not be implemented in time, given the speed of global warming, she said. In addition, a solar storm or collision with stray space rocks could damage the shield, resulting in sudden, rapid warming with disastrous consequences.
Critics say the money is better spent on reducing greenhouse gases right here on Earth—which we know will work.
SRM option #3: Saving the Arctic
Arctic glaciers are melting at an alarming rate. If left unchecked, it will have a range of catastrophic effects:
Arctic temperatures are warming around four times faster than the rest of the world, threatening to trigger “tipping points” of extreme sea level rise and melting permafrost which could release methane, a potent greenhouse gas that could cause warming of up to 8°C.
So saving glaciers is top priority—and there are two very different approaches.
Marine cloud brightening: involves “spraying a fine mist of seawater into clouds so that the salt makes them brighter, and more reflective of the sun’s heat.” It is a pet project of billionaire philanthropist George Soros—who is funding the Center for Climate Repair:
The centre is proposing to use more than 500 ocean vessels powered by waves and wind to spray seawater into the atmosphere during the Arctic summer. The ships would imitate the natural process that occurs when waves break over the ocean, creating tiny droplets of water vapour that could become sunlight-reflecting clouds.
The process reflects sunlight away from the ice layer formed over the Arctic sea during the winter—and each year that layer will grow thicker. The aim is to “refreeze the Arctic.”
But, but, but: The idea of refreezing glaciers may sound uncontroversial, but critics warn of unintended consequences for global weather:
A lot of weather patterns like monsoons depend on the difference in heating between the continents and the oceans. If you do something to cool down the North Atlantic, let’s say to preserve the sea ice or Greenland glaciers, that shifts precipitation in the tropics. Every part of the atmosphere is connected, so if you don’t balance your warming and cooling very carefully, then you get all sorts of changes in the climate system, some of which are difficult to predict.
And much like any other SRM technique, it will have to be renewed every week—without fail—to avoid a catastrophic ‘termination effect’.
A giant sea curtain: This is sort of like the umbrella in space—except it’s an underwater curtain. Or rather a series of underwater curtains. The idea is to place them in front of Arctic ice sheets—to protect key glaciers from warming oceans:
“Glaciers are affected by warmer air which melts their surfaces but they are also eroded at their bases by warm seawater,” said Shaun Fitzgerald… one of the partners in the scheme. And as the oceans warm as the planet heats up due to climate change, the more intense is the erosion of ice at the bases of these glaciers.”
You can see how it would work below:
Point to note: The 100 km-long curtain will be moored to the sea bed—and rise up 200 metres. If ever executed, the Seabed Curtain project will be the largest geoengineering project to date.
But, but, but: Seabed curtains are just a hypothesis for now:
At this stage, engineering design concepts for subsea anchored curtains are insufficiently developed and too little is known about seabed conditions for total costs of fabrication and installation to be estimated with great confidence
And it will take a decade or even two for the actual curtains to be installed. That said, it will be cheaper than protecting our coasts from sea level rise—which is expected to cost $40 billion dollars per year for every metre of sea level rise by 2100.
The bottomline: Even supporters of geoengineering agree that it isn’t a magic bullet that will solve the planet’s climate crisis. Essentially, it’s a hack that could buy us time—which is something we don’t have.
Watch this excellent Vox video explainer on SRM. Current Affairs and Wired are brilliant in laying out the geopolitics involved in any kind of geoengineering—not everyone benefits equally. The Economist has an upbeat take on solar radiation management. New York Times reports on the latest kind of SRM: sun shades in space. For more on marine-focused measures, The Guardian has two good pieces on underwater curtains and ‘hurricane slaying’. MIT Technology Review has a fascinating piece on plans to give our oceans some ‘Tums’ to cure their acidity. For more on the carbon capture approach, check out the Financial Times (splainer gift link). TIME looks at how and why tech billionaires have taken the lead in funding geoengineering projects—and the hazards of the same.