Arguably, climate change is the greatest existential threat humanity has ever faced. Until now our response to that threat has rightly been to try and free ourselves from an over-reliance on fossil fuels and cut greenhouse gas emissions. But what happens if that’s not enough? What if climate change has already gone too far and grown too rapidly to be reversed?
The Paris Agreement on climate change certainly provided validation for commentators who had been saying for years that we need to make changes and we need to make them now, and it’s heartening to see the vast majority of countries working together and combining the political, economic and social will of their people to meet the threat of climate change head on. Cutting emissions though is only one technique for fighting climate change, and not everyone sees it as the only tool in our arsenal.
The Paris agreement is a major step in the right direction, but it falls a long way short of the giant leap needed to tackle climate change
The Paris Agreement laid out a framework for, within this century, keeping global temperatures below 2°C above pre-industrial levels, while also optimistically challenging nations to go even further and limit the temperature increase to 1.5°C. The targets are ambitious on their own, and that’s before you elect a climate change denier/sceptic like Donald J Trump to the most powerful position in the world. But as stringent and as challenging to achieve as the Paris targets are, some believe they don’t go far enough. Speaking to the Guardian, Asad Rehman, international climate campaigner at Friends of the Earth, said: “The Paris agreement is a major step in the right direction, but it falls a long way short of the giant leap needed to tackle climate change. Far tougher action is needed to rapidly slash emissions.”
Ultimately, net greenhouse gas emissions need to be reduced to zero to limit climate risk, and even then eliminating emissions does not eliminate climate risk, because it does nothing to address emissions already in the atmosphere.
If climate change is the greatest existential threat humanity has ever faced then perhaps we need to think bigger when looking for solutions. That’s not to say that we necessarily need to replace cutting emissions, but rather, we should be looking for something to supplement it. And that’s where geoengineering comes in.
As engineer, physician, entrepreneur and creator of the X Prize Foundation and Singularity University, Dr Peter Diamandis, said in an interview with Tim Ferriss: “The fact of the matter is we are a smart species, and while we should be trying to reduce CO2 and go to an electric and solar economy, if we’re screwed I don’t want to sit here and boil, I’d like to take some actions to reduce that please, and there are actions we can take.”
What is Geoengineering?
Geoengineering is essentially a catch-all term that refers to techniques that could be used to artificially engineer the climate’s temperature. The concept isn’t a new one – the ideas were first kicked around in the 1960s – but given the current political climate and the pessimism over whether we will be able to meet the targets set out in the Paris Agreement, it’s certainly a technique that has seen its profile raised in recent times.
There are two major types of geoengineering being discussed. The first of which is concerned with removing greenhouse gases, which includes carbon and methane. This technique is considered relatively benign because it directly addresses the increasing concentrations of greenhouse gases that are causing global warming and can logically be combined with emissions mitigation as a response to climate change.
The second major, but far more controversial, example of geoengineering is solar radiation management (SRM). Solar radiation management or solar geoengineering is the process by which humans might deliberately reduce the effect of heat-trapping greenhouses gases, particularly carbon dioxide, by reflecting a small fraction of sunlight back to space. This technique would balance the warming from greenhouse gases with cooling that could be done by releasing aerosols into the stratosphere or by brightening clouds.
“The one thing that I would say with solar radiation management is that you can get it to work quickly and I’m pretty sure that it would work effectively – at least for small temperature changes – but there’s a lot of devil in the detail about how you can do any sort of deployment, what altitude you inject at, what latitude you inject at and what particles you use,” says professor of Atmospheric Science at the University of Exeter, Jim Haywood.
Geoengineering isn’t Superman
There’s a theory about Superman. It goes that while he’s going all over the world saving people, nobody else bothers to lift a hand because they live safe in the knowledge that, oh well, Superman will clean it up. And that’s pretty much the main – but not the only – criticism levelled at geoengineering.
But geoenginering isn’t a Superman, solve-all solution. It’s doesn’t replace cutting emissions and it shouldn’t be viewed as our last-minute salvation. It’s a short-term solution that wouldn’t deal with the root cause of climate change, and beyond contributing to a kind of global hubris there are more risks associated with SRM. For a start, it’s hard to gain global approval for a technique that could be used unilaterally, and while SRM may benefit some nations it could have a disastrous effect on others.
“If one country were to geoengineer in the Northern Hemisphere you would actually end up pushing the rain bearing monsoon clouds to the South, which would have some pretty devastating effects on places like the Sahel and India,” says Haywood.
If one country were to geoengineer in the Northern Hemisphere you would actually end up pushing the rain bearing monsoon clouds to the South, which would have some pretty devastating effects
Naomi Klein makes the same point in her book This Changes Everything that SRM originating in the Northern Hemisphere could have disastrous effects on the African and Asian summer monsoons. One study examining a Northern Hemisphere point of origin estimated a 60% to 100% decrease in plant productivity in the Sahel.
Africa would fare better with a Southern Hemisphere point of origin, but this would come at the expense of increased hurricane frequency in the United States. While that’s not ideal, it’s certainly preferable, but as Klein said: “Does anyone actually believe that geoengineering will be used to help Africa if that help could come only by putting North America at greater risk of extreme weather?”
Some scientists believe threat of deploying SRM and the risks associated with its use may serve as a powerful reminder of the pressing need for action on emissions. Although, given Trump’s scepticism on climate change and the fact that he has given a platform to geoengineering apologists like David Schnare, an architect of Trump’s Environmental Protection Agency transition, and US Secretary of State Rex Tillerson – who once said climate change was an “engineering problem” that “has engineering solutions” – it’s unlikely that he will heed that message.
But as SRM advocate and Harvard engineer David Keith said in a paper on SRM, Trump favouring geoengineering as the sole response to climate change isn’t a good thing either. “Under a pessimistic scenario, a Trump administration might gut climate and related geoscience research, eliminate the USGCRP, make deep cuts to Department of Energy renewable energy programmes, kill the Clean Power Plan, eliminate the federal renewable production tax credit, and withdraw from the Paris Agreement.
“It would be counterproductive to establish a formal federal solar geoengineering research program under this scenario because the likely result would be that forces lobbying for climate action would single out and attack research on solar geoengineering, labelling it as an excuse for inaction,” said Keith.
How do we get sulphur in the air?
Ultimately though, like Singularity University’s Dr Peter Diamandis, I don’t want to sit here and boil, so providing we have a global consensus, would it be possible to use SRM if we needed to? Well at the moment the technology has only ever been tested using computer models to simulate its effectiveness, and as Keith points out: “There might be some yet undiscovered risk making the technology much less effective in reality than the largely positive story told by computer models.”
Some people told about what geoengineering entails – flying a plane over your daughter’s school and spraying sulfuric acid in the air – become stronger advocates of mitigation
In order to physically test SRM Keith and his colleague Professor Frank Keutsch have proposed flying a balloon, filled initially with frozen water, about 20km into the air to quantify the microphysics of introducing tiny particles into the stratosphere and to improve our knowledge of the risks and benefits of solar geoengineering in large atmospheric models. Later tests might include tiny amounts of calcium carbonate or sulphates.
Testing may not be popular, but as Alan Robock, professor of climate science in the Department of Environmental Sciences at Rutgers University, says, increased publicity about the realities of SRM also may be no bad thing. “Some people told about what geoengineering entails – flying a plane over your daughter’s school and spraying sulfuric acid in the air – become stronger advocates of mitigation. If we discover SRM is too risky, that will increase the push to do mitigation,” says Robock.
At the minute scientists are still investigating the risks associated with SRM, but even if they decided that SRM was worth the risk and should be used, the technology needed to deploy it on the scale that would be required doesn’t exist.
“You’re talking about [releasing] millions of tonnes of sulphur dioxide, for example, into the stratosphere and that’s just not easy to do. You want to inject that at altitudes above 20km, and that is enormously high; there’s very few aircraft that can fly at 20km and we certainly don’t have the payloads, so that’s one big thing against them,” says Haywood.
“You could use rockets but their payloads are very small. There has been suggestion about tethered balloons but there’s a whole plethora of problems for landing them, including things like lightning, icing, turbulence, a whole bunch of technical and technological barriers that are in the way. Regarding, marine cloud brightening, a huge amount of technical barriers are in the way still and the amount of injection that you might need would extraordinarily large.”
Put simply, we don’t know how to deploy SRM and without conducting field experiments we’ll never know how dangerous artificially altering the climate would be, so many scientists, including the UK Royal Society and US National Academy, support continued research. The consensus is that geoengineering techniques like SRM won’t replace cutting emissions; they will work in support of that aim. That’s not to say there isn’t a healthy fear surrounding a technique that, without being hyperbolic, would aim to hack the planet’s climate and block out the sun.
“I think it’s rather like people who work on things like nuclear winter. They don’t work on things like nuclear winter because they think it’s a good idea,” says Haywood. “They work on it because they want to know the potential outcomes and cataclysmic outcomes of nuclear war. Not everyone has to agree with some of the things that we’re working on. I don’t know whether geoengineering is a good idea or not and I think that the jury is still certainly out on that.”