Climate engineering

In the history of environmental policy it has long been accepted that cutting pollution at its source is usually better than 'end-of-pipe' solutions aimed at moderating the damage after it has been done. In the case of greenhouse pollution, it is a lesson some want to abandon in the most dramatic way. The best definition of geoengineering is 'the deliberate large-scale manipulation of the planetary environment to counteract anthropogenic climate change'.46 Methods fall into two types: carbon dioxide removal from the atmosphere, and solar radiation management aimed at reducing solar radiation coming in or reflecting more of it out.47 Various schemes have been put forward to remove carbon from the atmosphere. Fertilising the oceans with iron filings is thought to promote the growth of tiny marine plants called phytoplankton, which absorb carbon dioxide as they grow and, on death, take carbon to the ocean depths. Trials have been unpromising, and it is feared the technique would create 'dead zones' in the ocean. Another scheme aimed at hastening the removal of carbon dioxide from the atmosphere is to install in the ocean a vast number of floating funnels that would draw nutrient-rich cold water from the deep to encourage algal blooms that suck carbon dioxide from the air and then take more carbon back down. This idea has met with little enthusiasm.48 A third idea is to build thousands of devices, called sodium trees, that would extract carbon dioxide directly from the air and turn it into sodium bicarbonate from which carbon dioxide could be separated, using a method the inventors are keeping secret, before being safely disposed.49 This too remains speculative, and it is hard to see how it would be cheaper to extract carbon dioxide from the air, where its con centration is 0.04 per cent, than from the exhaust of a coal-fired power plant.

Rather than removing surplus carbon dioxide from the atmosphere, most geoengineering schemes are aimed at cooling the planet by increasing the Earth's albedo, that is, the extent to which it reflects incoming solar radiation. Some of the ideas would be far-fetched even in a science fiction novel, such as the proposal to send ten trillion 60-centimetre reflective discs, in lots of one million every minute for thirty years, to a point in space known as L1, which is 1.5 million kilometres from Earth towards the Sun.50 Another idea is to launch specially designed, unmanned ships to plough the oceans, sending up plumes of water vapour that increase cloud cover. Up to 1500 dedicated vessels would be needed, but they would do nothing for ocean acidification. Others have suggested converting dark-coloured forests into light-coloured grasslands. Or we could mandate the whitening of city rooftops and roads, a requirement already for some houses in California, although the creation of shining cities could offset warming only a little.51

The option that is taken most seriously is altogether grander in its conception and scale. The scheme proposes nothing less than the transformation of the chemical composition of the Earth's atmosphere so that humans can regulate the temperature of the planet as desired. It involves injecting sulphur dioxide gas into the stratosphere, 10—50 kilometres above the Earth's surface, to create sulphate aerosols, particles that reflect solar radiation. Currently the atmosphere reflects about 23 per cent of solar radiation back into space, and it's estimated that the injection of enough sulphate aerosols to reflect an additional 2 per cent would offset the warming effect of a doubling of atmospheric carbon dioxide.52

In the stratosphere sulphate particles remain in place for one or two years, unlike aerosols in the lower atmosphere that may last only a week.53 The effect would be similar to a volcanic eruption, with analysts often pointing to the 1991 explosion of Mount Pinatubo, the sulphur and silicate ash from which cooled the Earth by around half a degree in the first year and by somewhat less for the next couple of years.54 Another analogy is the brown haze, due largely to the burning of fossil fuels, that envelops the lower stratosphere and is concentrated over South Asia and China. By cutting the amount of incoming solar radiation, the haze keeps the Earth cooler than it would otherwise be, a process of 'global dimming' that masks the effect of global warming.55 Air pollution laws in affluent countries have reduced smog and allowed more solar radiation to reach the Earth's surface.56 The gains are being eroded by pollution from the expansion of global aviation. It is estimated that when all aircraft were grounded for three days after the 9/11 attack on the United States, daytime temperatures in that country rose as the skies cleared.57

Attempting to regulate the Earth's climate by enhanced dimming is fraught with dangers. We saw in the first chapter that the absorption of carbon dioxide by the oceans is an essential component of the carbon cycle. The oceans absorb around a third of the extra carbon dioxide in the atmosphere arising mainly from the burning of fossil fuels. The acidity of the oceans is slowly rising, dissolving corals and inhibiting shell formation by marine organisms.58 Injecting sulphur dioxide into the stratosphere (along with other schemes aimed at enhancing the Earth's albedo) would do nothing to slow the acidification of the oceans. In other words, responding to warming by reducing the amount of solar radiation reaching the Earth's surface disregards the complexity of climate change; it is not just about the atmosphere but the entire carbon cycle that governs life on Earth.

In Fixing Climate, Robert Kunzig and Wallace Broecker tell the story of the eminent geoscientist Harrison Brown, who in 1954 wrote a book in which he proposed solving world hunger by increasing the carbon dioxide content of the atmosphere to stimulate plant growth.59 Brown suggested the construction of 'huge carbon-dioxide generators pouring gas into the atmosphere', and calculated that doubling the amount in the atmosphere would require the burning of at least 500 billion tonnes of coal. Brown's book was endorsed by Albert Einstein. His wish has come true: we have huge carbon dioxide generators pouring gas into the atmosphere. They are called coal-fired power stations. Curiously, it was one of Brown's students, Charles David Keeling, who a decade later, from his measuring station on Mauna Loa in Hawaii, first alerted the world to the rising concentration of carbon dioxide in the atmosphere and its implications for the warming of the world.

Harrison Brown wanted to pump carbon dioxide into the atmosphere to improve the lot of humankind. Today there is incipient pressure to pump sulphur dioxide into the atmosphere to control the effects of pumping too much carbon dioxide into it. (There was an old woman who swallowed a fly . . .) Although our understanding of the effects of climate engineering is rudimentary to say the least, one effect of it may indeed be to increase hunger. A study published in 2008 in the Journal of Geophysical Research used a comprehensive atmosphere—ocean circulation model to simulate the effects of the proposed injection of sulphur dioxide into the stratosphere. The authors found that it would disrupt the Asian and African summer monsoons, reducing the food supply for billions of people.60

Although ideas for climate engineering have been around for at least twenty years, until recently public discussion has been discouraged in the scientific community. Environmentalists and governments have been reluctant to talk about it too. The reason is simple: apart from its unknown side effects, geoengineering could become a substitute for reducing emissions. Economically it is an extremely attractive substitute because its cost would be 'trivial' compared to those of cutting carbon pollution—cheap enough for a single country easily to offset the emissions of the whole world.61

Most scientists at the forefront of climate research fear that broaching the subject will weaken resolve to cut emissions. Governments fear being accused of wanting to escape their responsibilities by pursuing science fiction solutions. The topic is not mentioned in the Stern report and receives only one page in the Garnaut report. As a sign of continuing political sensitivity, when in April 2009 it was reported that President Obama's new science adviser John Holdren had said that geoengineering is being vigorously discussed in the White House as an emergency option, he immediately felt the need to issue a 'clarification' claiming that he was expressing only his personal views.62 Holdren is one of the sharpest minds in the business and would not be entertaining 'Plan B', engineering the planet to head off catastrophic warming, unless he was fairly sure Plan A would fail.

Nevertheless, so anxious are scientists at the escalation of emissions and the tardiness of the response that some now feel emergency measures must be considered. The dam broke with a 2006 editorial by the eminent German atmospheric chemist Paul Crutzen. Crutzen, who won the 1995 Nobel Prize for Chemistry for his work on the hole in the ozone layer, wrote that cutting emissions is 'by far the preferred way' to respond to warming, but in the absence of resolute action it is now time to explore 'the usefulness of artificially enhancing earth's albedo and thereby cooling climate by adding sunlight reflecting aerosol in the stratosphere'.63 He stressed that plans to alter the chemical composition of the atmosphere should be seen as an escape route if global warming gets out of control. The very best outcome would be for measures to be taken to obviate the need to enhance the Earth's albedo, although this 'looks like a pious wish'. Crutzen is one of the growing number of scientists arguing that we need to consider Plan B. The foremost scientific institutions now agree, with the US National Academy of Sciences organising a conference and the Royal Society issuing a report in September 2009.64

As we will see, not all influential advocates of climate engineering adopt a cautious approach; some are gung-ho. When the potentially severe side effects of geoengineering are pointed out the more cavalier climate engineers say they can be managed with other techniques, such as spreading lime in the oceans to counter acidification. (She swallowed a spider . . . ) They might concede that liming the seas would not be feasible as a generalised response, but it could still be deployed to protect highly valued zones.65 One idea is to offset acidification by installing a network of undersea pipes that inject alkalis around sites such as the Great Barrier Reef.66 If, in order to avoid phasing out coal, turning the planet into a museum of natural artifacts while the rest goes to ruin sounds demented then you are clearly neither a scientist channelling Robert Boyle's dream of the 'empire of man' over nature, nor a neoclassical economist confident that we can pick out ecosystems valuable enough to save, nor a coal company executive who has relinquished his soul.

In classical Athens hubris was a crime. In a memorable instance, after Achilles killed Hector he tied the body to a chariot and dragged it around. Humiliation of a corpse, although unique for its brutality, reflected the same hubris that Agamemnon displayed when he desecrated a divine tapestry by walking on it. In modern times, parallels can be seen in the willingness of US soldiers at Iraq's Abu Ghraib prison to take photographs of their captives in humiliating poses.67 In Ancient Greece Hubris was paired with Nemesis, the god of divine retribution, whose 'blade of vengeance . . . yields a ripe harvest of repentant wo'68 on those who imagined themselves to be beyond the reach of the gods or put themselves above the laws of men. Today, we expect hubris to be accompanied by foolishness, a wilful disregard for the consequences of our actions. Messing with Gaia will perhaps provide the material for the legends of the twenty-second century.

We moderns believe implicitly that technology can solve any problem because we understand the world mechanically and because growth based on technological advance has been the easy way to resolve social conflict. Changing technologies always seems easier than changing people or challenging power. In 1959 the philosopher Karl Jaspers wrote in response to the threat to human existence posed by the atom bomb: 'We want to find salvation in a technological conquest of technology—as if the human use of technology might itself be subject to technological direction.'69

I have written before of the wealthy Texans who enjoy sitting in front of a log fire.70 As it is hot in Texas, this can only be done comfortably by turning on the air-conditioner. Geoengineering is akin to those Texans responding to overheating by turning up the air-conditioning while continuing to pile more logs onto the fire. For millions of years the temperature of the Earth and the amount of carbon dioxide in the atmosphere have more or less moved together, creating ice ages and warm epochs. The relationship is governed by primary factors (known as forcings)—notably peaks of solar radiation, volcanic events, methane release and, now, human release of fossil carbon—and secondary feedbacks— especially ice melt changing the Earth's albedo and carbon dioxide release from the land and oceans.71 Recent research indicates that the interaction is moderated by life forms that benefit from keeping the temperature in a habitable state.72 Recourse to climate engineering to counter human-induced warming is an unconscious attempt by one species to decouple the great process that links the composition of the atmosphere to the temperature of the Earth and the biotic systems of the land and oceans. Instead of decoupling growth of the economy from growth of carbon emissions, the climate engineers want to decouple global warming from growth of carbon emissions.

The implications are sobering. In August 1883 the painter Edvard Munch witnessed an unusual blood-red sunset over Oslo. He was shaken by it, writing that he 'felt a great, unending scream piercing through nature'. The incident inspired him to create his most famous work, The Scream.73 The sunset he saw that evening followed the eruption of Krakatoa off the coast of Java. The explosion, one of the most violent in recorded history, sent a massive plume of ash into the stratosphere, causing the Earth to cool by more than one degree and disrupting weather patterns for several years. More vivid sunsets would be one of the consequences of using sulphate aerosols to engineer the climate; but a more disturbing effect would be the permanent whitening of daytime skies.74 A washed-out sky would become the norm. If the nations of the world resorted to climate engineering as an expedient response to global heating, and in doing so relieved pressure to cut carbon emissions, then as the concentration of carbon dioxide in the atmosphere continued to rise so would the latent warming that must be suppressed. It would then become impossible to stop sulphur injections into the stratosphere, even for a year or two, without an immediate jump in temperature. It's estimated that, if we did stop, the backup of greenhouse gases could see warming rebound at a rate 10—20 times faster than in the recent past,75 a phenomenon referred to, apparently without irony, as the 'termination problem'.76 Once we start manipulating the atmosphere we could be trapped, forever dependent on a program of sulphur injections into the stratosphere. In that case, human beings may never see a blue sky again.

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