Pessimism is growing about humanity’s ability to save the planet as world leaders prepare to convene for climate change talks at the COP26 summit in Glasgow on October 31. Faced with increasingly apocalyptic projections, some scientists are calling for plans to cool the planet with geoengineering. But is this a realistic path out of the nightmare?
UN climate experts were unanimous in their latest report published in August: Unless we keep global warming below 1.5 degrees Celsius, the earth will be racked by heatwaves, cyclones and storms, entire species will be wiped out, and large swathes of humanity will have to leave their homes when coastal settlements go underwater.
As despair growths about humanity’s ability to avoid this fateful threshold, researchers are looking at geoengineering as a potential means of reversing the damage.
“Geoengineering is a way of using various technological tools to cancel out the environmental effects of human actions,” explained Sofia Kabbej, a researcher in the Climate, Energy and Security Programme at France’s Institute of International and Strategic Relations.
Sci-fi or reality?
A range of ideas come under the umbrella of climate geoengineering. Some seem totally fanciful, even dangerous. But other technologies are already operational.
“There are two categories of geoengineering,” said Roland Séférian, a climatologist at France’s Meteorological Office.
The first – and most controversial – involves ways of “modifying solar radiation”, Séférian noted. One such idea is to “reproduce what happens during volcanic eruptions when clouds of dust emerge in the sky and form a kind of screen between the sun and the earth, cooling the atmosphere in the process”.
As things stand, this is still just an idea scientists are thinking about. But for several years a team of researchers at Harvard University led by scientist David Keith have been planning to test it in real conditions. In 2021, this team intended to launch two balloons into the stratosphere in Sweden and release several kilos of calcium carbonate. However, vociferous opposition from locals and numerous NGOs put an end to this project.
Another technique is to “whiten” cloud formations by spraying salt into the atmosphere to reflect more of the sun’s rays – and consequently heat – thereby limiting the warming of the oceans.
An experiment was carried out on a small scale in Australia in 2020. But research into this technology is still in its infancy. Dozens of similar plans have been suggested – some rather eccentric and of dubious plausibility – including putting mirrors in space and even modifying the earth’s trajectory.
The second category of geoengineering consists of projects to take CO2 out of the atmosphere. “Some potential means of doing this have already been widely explored,” Séférian pointed out. Myriad techniques are being considered, from using natural carbon sinks such as forests or oceans to installing carbon vacuum cleaners in various places to even putting filters on factories.
“One approach we’re already using a lot in trying to address climate change is planting trees to capture CO2,” Séférian continued.
Outside of that natural means of capturing carbon, two technologies were mentioned in the IPCC report as potential methods of taking CO2 out of the atmosphere.
The first is called direct air capture (DCA), which involves installing kinds of vacuum cleaners to suck CO2 out of the air. The carbon is then buried underground. Some 20 such projects are already in place across the globe, according to the International Energy Agency. Swiss company Climeworks, for example, attached carbon suction machines to a waste incineration plant in the Zurich region.
The second such technology is called bioenergy with carbon capture and storage (BECCS). This means producing energy by burning biomass – such as wood and agricultural waste – trapping the resultant CO2 and burying it underground.
So far, neither technology has proven its worth. DCA looks inefficient, requiring a lot of energy to work. Meanwhile, there may not be enough arable land for planting forests or using BECCS to make a significant difference in tackling climate change.
The chimera of a quick fix?
But these geoengineering technologies worry many environmentalists. They fear that focusing on a technological fix will distract attention from the urgent task of drastically reducing CO2 emissions.
“Affecting how the sun’s rays reach earth would amount to giving humans quasi-divine status,” Kabbei said. “And there’s something quite problematic about that.”
Some on the political left especially may also be concerned that oil companies stand to profit handsomely from it. “It’s a huge financial opportunity for them,” Kabbei put it. “Carbon capture can only happen through the transport of CO2 – which requires pipelines and storage space; the kind of infrastructure oil companies have.”
A further problem for some critics is that geoengineering is something only countries in the global developed countries can afford to do – while the worst effects of climate change will likely be endured by underdeveloped countries.
And with geoengineering technologies still at an embryonic stage, scientists do not know what unintended consequences they might create.
“Even with the best scientific models, it’s hard to see exactly what would happen if people tried to absorb or bounce back solar radiation,” Séférian said. “CO2 capture and storage also raises questions: What would happen if the carbon leaks during transport? How long could it stay buried?”
Despite these concerns, given the way things are going “we can’t be 100 percent sure we’ll never need this technology”, said Olivier Boucher, an expert on geoengineering technology at the CNRS research institute in Paris. “Maybe we’ll find out that these ideas don’t work out in practice – but in any case it’d be a waste to deprive future generations of our work on these possibilities.”
“Anything to do with modifying solar radiation should be seen as a last resort,” Boucher continued. “But – in my opinion – CO2 capture and storage techniques really could become tools to help combat global warming.”
Séférian agreed: “It’s pretty likely that we’ll have to use CO2 capture technology in order to achieve carbon neutrality,” he said. “And the more we fall short with our current policies to tackle climate change, the more it will become inevitable – even though, in an ideal world, we shouldn’t need to use it.”
In any case, the research is continuing – although there is no international framework to regulate it.
An international convention prohibiting the use of “environmental modification techniques” for military purposes was adopted in 1976 – but its scope is limited. States and private actors can thus develop their own projects as they see fit.
“Right now it’s early days for geoengineering, but it’s definitely going to become a lot more salient within the next few years,” Kabbej said. “So countries are going to have to start talks to agree on how it should be done.”
“There’s got to be a public debate,” Séférian added. However, it is not on the official agenda for COP26. “It’s certainly something that we should be talking about, but it’s not a priority at these stage. The important thing is reducing CO2 emissions. Geoengineering comes later.”
This article was adapted from the original in French.