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Blue-sky thinking: can science save us from climate change?

The Climeworks carbon dioxide removal plant in Zurich, Switzerland is capable of drawing down 900 tonnes of the gas every year. Photo: Julia Dunlop

I’m not sure where I expected to find the front line in the fight against climate change, but it wasn’t in Switzerland’s answer to Swindon. Yet here in an industrial and retail estate on the outskirts of Zürich, perched on top of a waste incinerator and sandwiched between a sex-toy megastore and the rolling alpine countryside, a Swiss start-up is mounting a new offensive against the world’s rising temperatures.

Climeworks has been working on carbon dioxide removal (CDR) for a little over a decade and this plant is its biggest to date. It comprises 18 CO2 collectors, each capable of drawing 50 metric tonnes of carbon dioxide out of the air every year. So in the hours Climeworks’ communications manager, Louise Charles, and I have been talking the fans have just about wiped clean the emissions from my flight over from London. Not that Charles sees it that way. “We’re not your silver bullet,” she says sternly. “You cannot just expect us to draw down what you are putting up.”

It may not be my silver bullet, but the CDR pioneered by Climeworks could be one of the key weapons in the war on climate change. And according to the UN Intergovernmental Panel on Climate Change (IPCC), we need help from wherever we can get it. Its special report on global climate change, published on 8th October 2018, made for alarming reading. In it the world’s leading climate scientists issued a stark warning that urgent changes are needed for global warming to be kept within a maximum range of 1.5°C above pre-industrial levels.

The report makes it clear that in the next 12 years we need to radically decrease the 38.2 billion tonnes of carbon dioxide the IPCC estimates is released into the air annually from the burning of fossil fuels. If we fail, we risk unleashing a crescendo of deadly storms, floods and droughts. Hundreds of millions of people will be pushed into poverty and thousands of species will become extinct.

Most of the IPCC document stresses the need to reduce global emissions, but an alternative plan makes a brief appearance in its fourth chapter. Geoengineering is the deliberate intervention in the planet’s ecosystems to counteract climate change and broadly splits into two camps: carbon dioxide removal and solar radiation management (SRM). While SRM has divided the report’s writers, and the wider scientific community, CDR seems to unite them. The report stresses that “unless affordable and environmentally and socially acceptable CDR becomes feasible and available at scale well before 2050, 1.5°C-consistent pathways will be difficult to realise.”

“The IPCC special report marked a milestone,” says Louise Charles. “Climeworks, driven by our founders, engineers Christoph Gebald and Jan Wurzbacher, has for a long time believed direct air-capture technology is needed on a large scale to help tackle the climate issues we are currently facing. We all need to do all we can to reduce emissions, but that won’t be enough on its own. We also need to actively remove CO2 from the atmosphere.”

“We’re not your silver bullet”: Louise Charles at Climeworks’ Zürich facility. Photo: Marcus Webb


Clearing the air

There are a number of different ways that humans can remove CO2 from the air. The simplest is afforestation – planting trees on land that has not been forested for decades and letting them use up CO2 during photosynthesis. But afforestation takes time, land and money, which few countries seem keen to invest, and can have a considerable impact on food production.

There are a number of options involving the ocean including upwelling, whereby long pipes are used to pump water from the depths to the surface, in the hope that this new, cooler, nutrient-rich water will stimulate phytoplankton activity which will capture CO2. When the plankton die, they will fall to the seabed taking the absorbed carbon with them, effectively removing it from circulation. Phytoplankton could theoretically also be encouraged by fertilising the oceans with huge amounts of iron filings. Another option is alkalinisation, in which lime is added to seawater, altering its chemistry to be less acidic and increasing its capacity to absorb carbon dioxide. There is little agreement on how effective any of these options would be or about the impact they might have on marine life. Which brings us to direct air capture, the approach taken by Climeworks.

The company’s Zürich facility, which opened in 2017, works by drawing air through giant extractors onto a filter to which CO2 molecules are chemically bound. Once the filter is saturated it is heated to 100°C, which releases the CO2, to be pushed through pipes into a nearby greenhouse. The farmer who owns the greenhouse pays Climeworks to use the gas as an airborne fertiliser – higher CO2 concentrations inside a greenhouse can result in a 20 percent improvement in crop yield.

Climeworks was designed as a commercial venture from the start. “Ultimately it has to make sense as a business,” says Charles. But it’s not cheap. Climeworks’ engineers estimate that each tonne of carbon dioxide costs $600 to remove, and the company’s goal is to bring that down to $100.

The site of one of humanity’s best hopes in tackling climate change permanently reeks of burning cabbage”

The process requires energy, which is why the facility is situated on top of a rubbish incinerator: it uses electricity generated by Zürich’s waste. It’s also the reason why the site of one of humanity’s best hopes in tackling climate change permanently reeks of burning cabbage. Up close it’s an impressive ecosystem, a virtuous circle which even has large balloons to store CO2 captured overnight when it is not needed by the greenhouse (plants only absorb CO2 during the day as they need sunlight to photosynthesise).

Still, it’s difficult to envision how the technology could scale up to the point where it is extracting the “gigatonnes” of carbon dioxide climate experts believe is needed to meet the IPCC’s 1.5°C target. “Twelve years is not long,” admits Charles. “We would need a similar scale-up to the one we have achieved in the last ten years. When we founded the company we were capturing milligrams of CO2 a day in a lab. Really tiny amounts. And here we are ten years later capturing many thousands of tonnes of CO2 a year across all our operations. The challenge now is to succeed with a similar kind of scale-up.”

Scaling up means more CDR plants. A new bank of extractors is being built on the same pungent Swiss rooftop, and Climeworks has 14 plants in total, including in Italy and Iceland, where the facilities are powered by renewable energy, rather than energy from waste. It also means improving the technology’s efficiency. “What we see on the roof today is generation one of our technology,” says Charles. “Every year we will come out with a new technology generation. We already know exactly how we are going to optimise things, how we are going to make it more efficient, how we are going to bring the costs down.”


Stepping on the gas

But even if the gigatonnes of gas needed could be drawn down, what should be done with it? The agriculture and food-and-beverage industries currently use 30 million tonnes of CO2 a year in processes including the fertilisation of plants and the production of fizzy drinks. There are other areas where captured CO2 could be put to work, with the Japanese government’s Innovation for Cool Earth Forum estimating that 2.1 billion tonnes of carbon dioxide a year could be used for making renewable fuels and materials by 2030.

The numbers are based on the development of the Fischer-Tropsch process, a chain of chemical reactions that converts a mixture of carbon-heavy gases and hydrogen into liquid hydrocarbons which can be used as fuel, as well as in polymers, methanol, formic acid and in building materials such as concrete.

While most of these applications would reduce the amount of new carbon dioxide being produced, a lot of the gas would be re-released later in the cycle – when the fuel is burned, for example. But Climeworks is working on a project that would lock away carbon dioxide forever. This is where Iceland comes in.

We don’t need to just keep emissions flat, we need to be reducing them. We are going in the wrong direction at an increasing speed”

In October 2017 Climeworks joined the ambitious CarbFix project led by public utility company Reykjavik Energy at the Hellisheiði geothermal power plant in Iceland. As with its facility in Switzerland, Climeworks’ technology is used to capture carbon dioxide – but rather than the gas being reused, it is mixed with water and injected into underground basalt rock formations. The resulting chemical reaction forms carbonate minerals which permanently store the injected CO2: think fracking in reverse. The pilot scheme has been successful and to coincide with the IPCC report’s release, Climeworks announced it was expanding the project to 50 times the current capacity, meaning it will capture and store several thousand tonnes of emissions a year by the end of 2019.

It could be just the beginning. “Iceland was the best place to start, because there are huge amounts of this basalt rock we need,” says Charles. “There are multiple places in the US, in Africa and in the Middle East with a similar geology where this same process could be applied.” Climeworks estimates that by 2030 1.5 billion tonnes of CO2 could be locked away per year by CDR technology, and from 2050 onwards that figure could be as high as 10 billion tonnes – a quarter of what is currently emitted by burning fossil fuels annually.

Such ambitions, however, are unlikely to be enough on their own.


Breathing space

“The fact is we are very, very late in the game when it comes to trying to turn this climate ship around,” warns Gernot Wagner, a research associate at Harvard’s School of Engineering and Applied Sciences. “Despite lots and lots of people having said the same thing for a long time, and frankly us having known about this for decades, the world has not gotten around to doing enough to lower emissions.”

Wagner, a youthful-looking 38-year-old Austrian who delivers his dire warnings in a quick-fire staccato, co-authored the 2015 book Climate Shock: The Economic Consequences of a Hotter Planet. He has spent his career researching our warming earth and believes that the alarm bells rung by the IPCC report are nowhere near loud enough.

“The underlying science of the IPCC report is incredibly well done, but it’s based on findings from years ago,” he says. “It is not at the scientific frontier. We are now in a situation where global CO2 emissions are actually going up. Global fossil-based CO2 emissions were flat for three years in a row until 2016, but in 2017 went up and in 2018 they increased further. To hit 1.5°C we don’t need to just keep emissions flat, we need to be reducing them. We are going in the wrong direction at an increasing speed.”

Gernot Wagner, research associate at Harvard’s School of Engineering and Applied Sciences. Photo: Rose Lincoln

Given the timeframes, Wagner doubts that carbon capture will be enough on its own. “CDR is perfect in the sense that it actually tackles the root cause: excess CO2 in the atmosphere,” he says. “But it is slow and expensive.” Wagner says that solar radiation management is a “fast, cheap and imperfect” complement to CDR that could, he believes, buy humans the time they need to decarbonise the global economy and get CDR up to speed.

Solar radiation management involves reflecting a percentage of the sun’s light back into space in order to counter the effects of global warming by cooling the planet. Suggested methods have included painting cities white, launching giant mirrors into space, covering the Sahara in a reflective material and launching millions of ping pong balls into the world’s oceans. Wagner believes the most promising model is stratospheric aerosol injection, which would involve distributing particles into the upper atmosphere.

“How do we know stratospheric aerosol injection would work? Because volcanoes have been doing it forever,” he says. When a volcano erupts it spews tonnes of sulphur dioxide into the atmosphere along with copious amounts of ash. This gas spreads around the world and combines with water vapour to make aerosols, tiny droplets that reflect some sunlight away from the Earth, lowering its temperature. “Mount Pinatubo erupted in the Philippines in 1991 and global average temperatures in 1992 were half a degree centigrade lower,” says Wagner. “Now that doesn’t mean it’s a good idea, but it does mean that in principle it works.”

Good or not, solar radiation management is not a new idea. In 1965 the science advisory committee to Lyndon B Johnson submitted the very first climate change report to a United States president. It warned that “man is unwittingly conducting a vast geophysical experiment. Within a few generations he is burning the fossil fuels that slowly accumulated in the earth over the past 500 million years.”

The committee members warned that “the climate changes that may be produced by the increased CO2 content could be deleterious from the point of view of human beings”. The report concluded that solar radiation management could be a solution: “The possibilities of deliberately bringing about countervailing climatic changes therefore need to be thoroughly explored…”

This long-standing taboo has prevented the scientific community from doing research since 1965. We lost five decades”

Johnson made a speech to Congress about the report, stating that, “This generation has altered the composition of the atmosphere on a global scale through radioactive materials and a steady increase in carbon dioxide from the burning of fossil fuels.” He made no mention of geoengineering, however, and no thorough exploration was commissioned. Wagner believes this was because most politicians and many senior scientists found the solution too radical to comprehend. “It’s been met by this long-standing taboo,” says Wagner. “This has prevented the broader scientific community from doing research since 1965. We lost five decades.”


Throwing caution to the wind

Joanna Haigh, a professor of atmospheric physics at London’s Imperial College disagrees that those decades were lost. “There’s enough we know about solar radiation management now to make it not worth spending money on research and going to field trials,” she says. “It’s like testing an atomic bomb. Theoretically you know it works and the damage it can do, so why create it?”

Haigh is co-director of the Grantham Institute for Climate Change & Environment and was awarded a CBE for services to physics in 2013. She’s been studying the climate for over 40 years and manages to deliver both bone-chilling warnings and more reassuring observations in the same calm manner.

It is only the subject of SRM that provokes her to raise her voice. Haigh believes that far from saving the planet, solar radiation management could destroy it. “Climate models show quite clearly that yes, in terms of global average temperature you can compensate [for global warming with SRM], but you’re not ending up with the same atmosphere you started with,” she says. “You’re ending up with changes in the hydrology, especially in the tropics, in the monsoons, in the positions of the storm tracks. You’ve got a different climate system, one which could bring its own disastrous impacts even though the global average temperature possibly can be kept to zero change.”

If we were to reflect seven percent of sunlight back it would cause a snowball earth. It would freeze the planet to the equator, and life on earth would cease”

In December Climate Analytics, a non-profit climate science and policy institute based in Berlin, released a briefing entitled ‘Why geoengineering is not a solution to the climate problem’, which recommended a global ban on solar geoengineering. “SRM would alter the global hydrological cycle,” claims the report, highlighting the likely impact it would have on monsoon activity. “These [monsoon] rains not only play a vital role in food security and exports, but also provide essential water for very large, and often already vulnerable populations,” it states. And that’s not the only problem.

The Climate Analytics report also warns that once SRM begins it must be carefully maintained or risk exposing the world to “termination shock”. As aerosols disperse quickly, failure to maintain the levels would expose the planet to the full force of the sun’s rays once more which would result in “very rapid and large-scale planetary warming” that could occur “on a timescale of months”. If that weren’t enough, the report concluded that SRM could result in a major war. “SRM will strongly alter the climate system, producing ‘winners’ and ‘losers’ in different regions and with different levels of deployment,” it stated. “It could therefore become a source of massive conflict between nations.”

Wagner agrees that there are considerable risks. “Theoretically, solar geoengineering can wreak a lot of havoc,” he says. “It is a very powerful tool that if misused could do a lot of damage. If we reflect a fraction of a percent of sunlight back into space it would potentially do a lot of good, but if we were to reflect seven percent of sunlight back it would cause a snowball earth. It would freeze the planet to the equator, and life on earth would cease as we know it.”

Despite the apocalyptic vision of a misstep plunging earth into an ice age, heat shock or World War III, Wagner believes that humans have been left with no choice. “Whether you like solar geoengineering or not, our climate’s current trajectory and SRM’s fundamental properties point to it being a question of when, rather than if, we use it.”

The Hellisheiði geothermal power plant in Iceland. Photo: Arni Saeberg


The heat is on

The when could be sooner than you think. In November 2018, Wagner released the most detailed engineering analysis of SRM to date. It concluded that spreading particles into the stratosphere could cost as little as $2.2 billion a year.

The report found that the most cost-effective method would be to develop a new type of aircraft capable of delivering tonnes of sulphate particles at an altitude of 12 miles. At that height the particles would remain aloft for at least a year before dispersing: if the sulphates were released from the much lower levels reached by commercial jets, the particles would fall out of the sky in days.

Wagner and his fellow researchers have mapped out the cost of a 15-year programme which would begin with 4,000 flights a year and end with 60,000 flights a year by almost 100 aircraft. Wagner’s calculations are based on emissions being curbed from today’s levels but still rising – leading to 3°C of warming, a level considered catastrophic by climate scientists. He believes the programme would reduce warming by 0.1°C per year, with a total reduction of 1.5°C by year 15.

Wagner believes that people, rather than technology, will be the stumbling block. “The governance questions, the political-science questions, all these broader societal implications are much more important than the actual scientific technological questions,” he says. “We need to create the kind of global conversation that is necessary to lend this sort of potential intervention the legitimacy that is needed to ensure that whatever comes out on the other end is more of a success than a failure.”

Professor Haigh believes this is all just more hot air. “There’s got to be some sort of international body that’s going to decide who does what, where and when, and who controls it? I cannot see it,” she says. “If you consider the problems just getting to the Paris climate deal, which was an agreement just to do some good for the world… This is just fantasy, really.”

Haigh believes the debate over SRM detracts from what we as individuals need to do. “Geoengineering is not going to let us off the hook,” she says. “Nobody is coming to save us from climate change. We need to save ourselves. Eat less meat, travel less, have fewer children, spend the money that’s needed on green energy. We know what we need to do.”

If anything we need to stop people from doing too much solar geoengineering too soon, stupidly”

Wagner is less optimistic that the message will get through. “We could as a society decrease emissions significantly, but it’s not going to happen given our socioeconomic system,” he says. “We need to explore other options and pass that knowledge on to our children. They will have to make the tough decisions and the least we can do is arm them with the knowledge. If you ask me today a binary question of whether we should implement solar geoengineering tomorrow or never touch it I would vote for never touching it. What I’m arguing is that we should do more serious research on the topic because we simply can’t keep disregarding this option.”

And it may be the case that a nation, or even a wealthy individual, decides to launch an SRM project unilaterally. There would be nothing to stop them from playing with the earth’s atmosphere – but if they did there could be consequences for every human on the planet.

“That’s the real danger,” says Wagner. “It is the exact opposite of when it comes to incentivising mitigation action, where we need lots of people to take action now. If anything we need to stop people from doing too much solar geoengineering too soon, stupidly.”

We need to plant more trees and we need direct air capture and we need other approaches all working together”

In February 2019 a long-term forecast released by the UK Met Office warned that global temperatures could exceed 1.5°C above pre-industrial levels in the next five years. Until now, the hottest year on record was 2016, when the planet hit an increase of 1.11°C. The second hottest was 2017 (a 0.9°C rise) and eight of the warmest years on record have been in the last decade. If the earth keeps warming on the same trajectory we could hit a 4°C rise on pre-industrial levels by the turn of the century, at which point Wagner believes that our planet will become “largely unlivable”.

On Climeworks’ Zürich rooftop, Louise Charles stresses that no single thing – carbon dioxide removal, solar radiation management or a reduction in emissions – is likely to be enough on its own. “We are not the only way to solve this issue,” she says. “We see ourselves as part of this portfolio. We need to plant more trees and we need direct air capture and we need other approaches all working together… And we still might not get there. There is no get-out-of-jail-free card.”


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