Global dimming: technological fix or folly?

Sensemaking / Global dimming: technological fix or folly?

18 Apr 2011

Clive Hamilton highlights the global risks and implications of stratospheric spraying

Since its formation 4.5 billion years ago, the amount of solar radiation reaching the Earth has been regulated by the sun. Now we are not happy with the arrangement and want to take over regulation ourselves.

Space mirrors are science fiction, but plans to transform the chemical composition of the Earth's atmosphere through a programme of stratospheric aerosol injections are all too real.

If we have learned anything from the last two decades of climate research it is that the global climate system is fiendishly complex. We don't know what the consequences of enhancing 'global dimming' through aerosol spraying would be, and even with another two decades of intensive study, it's unlikely we could predict the global effects with any degree of accuracy.

Early studies suggest that, like some volcanic eruptions, stratospheric aerosol spraying could cause major changes in rainfall patterns. It may disrupt the Indian monsoon and African rainfall patterns, leading to widespread crop failures. These regional impacts would exacerbate the likely conflicts between nations over the optimal temperature at which the global thermostat should be set.

One of the most powerful arguments against enhancing global dimming arises from the fact that climate change is not only about global warming. The oceans absorb around half of the additional carbon humans are pumping into the atmosphere, causing its acidity to rise. The oceans are already around 30% more acidic than before the Industrial Revolution, impeding shell formation by marine organisms and jeopardising coral reefs.

Aerosol spraying may be able to offset warming, but ocean acidification would proceed unchecked as carbon concentrations rise. There is no known answer to acidification, other than crazy schemes to pump alkalis into the waters around coral reefs. So what are we to do? Sacrifice the oceans?

Aerosol spraying would also reduce the amount of direct solar radiation available for plant photosynthesis, and anything else which runs on sunlight, like renewable energy systems. The effect may be small, but many plant systems operate at the margin. A high-level aerosol haze would whiten the skies in the daytime and impede astronomers at night.

But perhaps the foremost danger of SRM is what is known as the 'moral hazard': the possibility that geoengineering would relieve the pressure on nations to cut their carbon emissions. Unrestrained growth in emissions would accelerate latent warming and thereby lock in the need for a spraying programme without end.

The analysts worry about how big a risk this is. Those with their feet on the ground know it is not a possibility, but a certainty. Once the floodgates open, governments and industry will seize on SRM as a means of getting themselves out of a tricky situation while carrying on with business as usual – particularly as controlling sunlight is expected to be much cheaper than cutting carbon emissions. The temptation to shift the burden from powerful industries and affluent consumers to the faceless victims of aerosol spraying will prove too great.

The build-up of latent warming would soon make it impossible to stop regulating solar radiation without drastic consequences. The 'rebound effect' of ending enhanced dimming – due to war, for example, or to a shortage of sulphur – would see accelerated warming, perhaps shifting the Earth to a new climate within months.

The perils of planetary technology

The moral implications of this generation committing the next 20 generations to permanent management of solar radiation are immense. Perhaps if the judgement were left to 'this generation' (as a whole) there would be less to worry about. But the decision as to how much solar radiation should reach the planet will depend on who makes it.

So who in practice will authorise sending up the specially equipped fleet of 747s, or turning on the spigot of the 40km Kevlar sky-tube? The Central Committee of the Chinese Communist Party? President Palin? A rogue billionaire? The military? At present there is no law to stop any of them doing just that. Whose interests do they serve? What is their preferred thermostat setting?

One thing seems certain: the poor and powerless will not be allowed near the control panel. Some climate engineers fear that a UN treaty to regulate SRM would prevent implementation, and even research. Yet, ethically, taking control of the Earth's atmosphere cannot be justified without the informed consent of those affected, especially the most vulnerable. The UN is the only route by which consent may be given, even if consent stops geoengineering in its tracks.

Commercial vultures are circling. Start-ups and venture capitalists are already making plans to cash in on planetary management technologies. Perhaps someone is already quietly acquiring control of the world's sulphur supply. Most sulphur used today is a by-product of oil and gas production, although a share is scrubbed out of the flue gases from coal-fired power plants. That would be the final irony: extracting sulphur before it pollutes the lower atmosphere in order to save ourselves by spraying it into the upper one.

The sulphur industry already has its own lobby group in Washington. Dominated by oil companies, it actively promotes greater use of sulphur. Once big corporations have a stake in any endeavour, they become a political force with an interest in growth. In the future, will the promotion of shareholder value in oil companies determine how much light reaches the Earth?

There lies perhaps the greatest anxiety about enhanced dimming: if we start a programme to reduce the amount of sunlight reaching the Earth, will we ever be able to stop it? Will enhanced dimming be locked in because it gives the green light to continued carbon emissions, and the overconsumption behind much of them? Will it create its own political and commercial power bloc? Will the rich who benefit ignore the pleas of the poor who suffer? Will we be too afraid to stop it because cessation risks disaster?

Global warming promises a grim future because we have come to believe that technology can solve any problem. But if technological thinking gave us the problem of climate change, is it not folly to believe that the same thinking will fix it?

Clive Hamilton is Professor of Public Ethics at the Centre for Applied Philosophy and Public Ethics in Canberra. He is the author of Requiem for a Species: Why we Resist the Truth about Climate Change (Earthscan 2010), and of a series of papers on geoengineering and the psychology of climate denial.

This article is taken from the Green Futures Special Edition, Under New Management.

Image credits: Steve and Donna O'Meara / National Geographic; cinoby / istock

What might the implications of this be? What related articles have you seen?

Please register or log in to comment.