One

Imagining an Engineered Climate

Techno-fixing the climate

The Nobel Prize-winning English scientist Michael Beard is on the point of unveiling to the world a wonder-fix for climate change. His solar-powered technology for splitting water into oxygen and hydrogen gas is about to demonstrate its vast potential for cheap, unlimited hydrogen-based energy:

The day after tomorrow a new chapter would begin in the history of industrial civilisation, and the Earth's future would be assured. The sun would shine on an empty patch of land in the boot heel of south-west New Mexico … and the storage tanks would fill with gas.4

But Beard's excessive and self-indulgent past behaviour catches up on him. His sins and misdemeanours lead to a tragicomic denouement as his cuckolded adversary takes a sledgehammer to the salvation technology, leaving nothing but wrecked machinery. Beard's dream of a techno-fix for climate change is crushed amid spiralling debts and the chaos of torn human relationships.

The above scenario is from the novel Solar, Ian McEwan's comic allegory of climate change. Finding a cheap and sustainable way of creating clean electricity without relying on fossil fuels is one way in which science and technology are frequently imagined to be able to fix climate change. And not just in fiction. At various times hopes have been raised that anthropogenic climate change can be solved through a transition to a hydrogen-based economy, through the wonder-technology of nuclear fusion or through a German-style Energiewende: an energy revolution based on large-scale deployment of solar, wind and other renewable energies.

But in recent years another discourse has emerged, in which science and technology are offered as a ‘fix’ for climate change, this time through the development and deployment of so-called geoengineering technologies (see Box 1.1). These rather eclectic technologies are united in their ambition to deliberately manipulate the atmosphere's mediating role in the planetary heat budget. They aim to do one of two things: either to accelerate the removal of carbon dioxide from the global atmosphere; or else to reflect more sunlight away from the Earth's surface and so to compensate for the heating of the planet caused by rising concentrations of greenhouse gases.

The possible realisation of geoengineering technologies – especially the idea of injecting sulphur gas into the stratosphere – was given a great scientific and psychological boost in 2006. The Nobel Prize-winning Dutch scientist Paul Crutzen wrote an influential article, titled ‘Albedo Enhancement by Stratospheric Sulfur Injections: A Contribution to Resolve a Policy Dilemma’.5 In it, he suggested that the time had come for Earth system scientists to seriously research this method as a backstop technology for limiting climate change – the ultimate techno-fix for climate change. Crutzen was no Beard. He was real rather than fictional; and he was rather more disciplined in his personal life than was Michael Beard. And he had won his Nobel Prize for work of great societal benefit. Rather than the abstract ‘Beard–Einstein Conflation’ with which McEwan's eponymous celebrity scientist had endowed the world, Crutzen's recognition in 1995 was for work conducted with two colleagues on the formation and decomposition of stratospheric ozone. This work had informed the 1985 Vienna Convention for the Protection of the Ozone Layer, which in turn led to the later global agreement to phase out production of the most damaging chloroflourocarbons that had been destroying stratospheric ozone at high latitudes.

Crutzen was careful to state in his 2006 article that injecting aerosols into the stratosphere was ‘by far not the best solution’ for climate change. Yet his intervention in 2006 spawned a series of research workshops, conferences, networks, studies, assessments and governmental hearings into the possibilities and risks of such a technology. The science reporter Eli Kintisch attended one such meeting in 2007, organised by the University of Calgary and Harvard University. ‘Should scientists study novel ways to alter Earth's climate to counteract global warming?’ asked Kintisch.6 The 50 elite researchers at the meeting concluded ‘yes’, but only after agreeing that ‘the road to understanding the science is fraught with booby traps and that deliberately tinkering with the climate could make the problem worse’.7 One of those scientists in attendance, David Battisti from the University of Washington, was seriously concerned about the meeting's outcome. Kintisch reported: ‘After speaking on the phone with his wife from his hotel room, Battisti confessed: “I told her this meeting is terrifying me”.’8

In this chapter I explain how this idea of creating a techno-fix for climate change by artificially reflecting sunlight has gained such plausibility in recent years and why some scientists such as Battisti might be privately terrified of the idea. But first I introduce the range of planetary intervention technologies that are often grouped under the label ‘geoengineering’.

What is geoengineering?

In controversial public debates it matters how terms are defined and understood. The term ‘geoengineering’ is a rather eclectic catch-all expression. The first use of geoengineering in the context of climate change was made by the Italian physicist Cesare Marchetti in 1977, in a rather obscure article titled ‘On Geoengineering and the CO2 Problem’. Marchetti was proposing to capture carbon dioxide emitted from power stations and to bury it either in the deep ocean (his preferred solution) or else underground, in the geological strata. Thirty years later, in the 2006 article referred to above, Paul Crutzen used the labels ‘geoengineering’ and ‘climate engineering’ interchangeably, to describe his proposal for stratospheric aerosol injection. More recently, the conventional definition of geoengineering has come to be this: ‘the deliberate, large-scale manipulation of the planetary environment in order to counteract anthropogenic climate change’. This definition is taken from the Royal Society's 2009 report Geoengineering the Climate: Science, Governance and Uncertainty (Royal Society 2009), which divides geoengineering technologies into two types: solar radiation management (SRM) and carbon dioxide removal (CDR).

The former set of technologies seeks to offset global warming by reducing incoming solar radiation; and it proposes to achieve this reduction by reflecting more sunlight back into space. Hence these reflecting technologies are sometimes called sunlight reflection methods (abbreviated with the same acronym SRM). These technologies include placing mirrors in near-Earth space orbit; injecting tiny sunlight-reflecting particles into the stratosphere (Crutzen's proposal); whitening low-level marine clouds by spraying seawater into them; and whitewashing dark urban infrastructures – roads, car parks, roof tops. The latter set of technologies seeks to remove carbon dioxide from the atmosphere and to secure it in long-term reservoirs. These sequestration technologies include ocean iron fertilisation, soil biochar, and carbon capture and storage. The latter is a process whereby carbon dioxide is captured either from the free atmosphere or from the waste flues of fossil-fuel powered stations. Box 1.1 offers a brief description of the main geoengineering technologies.

The first four technologies described below are sunlight reflection methods and leave atmospheric concentrations of carbon dioxide unaffected. In contrast, the four technologies in the second group remove carbon dioxide from the atmosphere and sequester or isolate the carbon in a variety of reservoirs, in effect reversing the process of fossil-fuel combustion.

Stratospheric aerosol injection This sunlight reflection technology seeks to mimic the cooling effect of huge volcanic eruptions. Millions of tonnes of hydrogen sulphide or sulphur dioxide would be artificially injected into the stratosphere, where these gases would oxidise into tiny sulphate aerosol particles, just a few tenths of a micron in diameter. Surviving here for a few years, these aerosols would scatter sunlight back into space, thereby reducing lower atmospheric heating. Other types of particle for injection have been suggested, but the favoured technology would use sulphur gas.

Marine cloud brightening Rather than ask sulphate aerosols to do the job of reflecting sunlight, this method would seek to accomplish it by whitening low-level clouds. The idea would be for mobile ships to spray jets of seawater droplets into the marine lower atmosphere. These would provide condensation nuclei on which cloud water droplets would condense, brightening the marine clouds that occur naturally over large parts of the world's oceans. Brighter clouds would reflect more sunlight back into space, cooling the lower atmosphere.

Orbital mirrors This method of sunlight reflection would insert trillions of tiny metallic reflectors into near-Earth orbit, to reflect the incoming solar radiation back into space before it ever entered the Earth's atmosphere. No chemicals would be involved, but the...