Friday, 5 April 2013


"Geoengineering is large-scale intervention in the Earth system to counteract human-induced climate change. There are two main types of geoengineering approaches: Carbon dioxide removal (CDR) and Solar radiation management (SRM)."

— University Of Exeter: Climate Change & Sustainable Futures.

In 2009, a Royal Society report warned that geoengineering was not an alternative to cutting greenhouse gas emissions, but conceded the technology might be needed in the event of a climate emergency.

Writing in the journal Nature Climate Change, Haywood and others show that moves to cool the climate by spraying sulphate particles into the atmosphere could go spectacularly wrong. They began by looking at the unexpected impacts of volcanic eruptions.

In 1912 and 1982, eruptions first at Katmai in Alaska and then at El Chichón in Mexico blasted millions of tonnes of sulphate into northern skies. These eruptions preceded major droughts in the Sahel region of Africa. When the scientists recreated the eruptions in climate models, rainfall across the Sahel all but stopped as moisture-carrying air currents were pushed south. 

Having established a link between volcanic eruptions in the northern hemisphere and droughts in Africa, the scientists returned to their climate models to simulate SRM projects.

The scientists took a typical project that would inject 5m tonnes of sulphate into the stratosphere every year from 2020 to 2070. That amount of sulphate injected into the northern hemisphere caused severe droughts in Niger, Mali, Burkina Faso, Senegal, Chad and Sudan, and an almost total loss of vegetation.

The same project had radically different consequences if run from the southern hemisphere. Rather than drying the Sahel, cooling the southern hemisphere brought rains to the Sahel and re-greened the region. But Africa's benefit came at the cost of slashing rainfall in north-eastern Brazil. 

The unintended consequences of SRM projects would probably be felt much farther afield. "We have only scratched the surface in looking at the Sahel. If hurricane frequencies changed, that could have an impact on the US," said Haywood. 

Matthew Watson, who leads the Spice project at Bristol University, said the study revealed the "dramatic consequences" of uninformed geoengineering.

"This paper tells us there are consequences for our actions whatever we do. There is no get-out-of-jail-free card," he told the British newspaper Guardian.

Whatever we do is a compromise, and that compromise means there will be winners and losers. That opens massive ethical questions: who gets to decide how we even determine what is a good outcome for different people?

"How do you get a consensus with seven billion-plus stakeholders? If there was a decision to do geoengineering tomorrow, it would be done by white western men, and that isn't good," Watson said.

The idea of applying large-scale technologies to manipulate the Earth’s global temperature in response to climate change, sounds like the plot of a science fiction novel. Nevertheless, it is migrating to the infinitely more unsettling realm of science policy. The notion of a direct intervention in the climate system — by removing carbon dioxide from the atmosphere, or reflecting a small amount of sunlight back out into space — is slowly gaining currency as a ‘Plan B’. The political subtext for all this is the desperation that now permeates behind-the-scenes discourse about climate change. Despite decades of rhetoric about saving the planet, and determined but mostly ineffectual campaigns from civil society, global emissions of carbon dioxide continue to rise.

This is the context in which several scary, implausible or simply sci-fi proposals are being put on the table. They range from the relatively mundane (the planting of forests on a grand scale), to the crazy but conceivable (a carbon dioxide removal industry, to capture our emissions and bury them underground), to the barely believable (injecting millions of tiny reflective particles into the stratosphere to reflect sunlight increasing albedo). In fact, the group of technologies awkwardly yoked together under the label "geoengineering" have very little in common beyond their stated purpose: to keep the dangerous effects of climate change at bay.

Playing around with the Earth’s systems at a planetary scale obviously presents a number of unknown — and perhaps unknowable — dangers. How might other ecosystems be affected if we start injecting reflective particles into space? What would happen if the carbon dioxide we stored underground were to escape? What if the cure of engineering the climate is worse than the disease? But I think that it is too soon to get worked up about the risks posed by any individual technology. The vast majority of geoengineering ideas will never get off the drawing board. Right now, we should be asking more fundamental questions.

Geoengineering differs from other approaches to tackling climate change not in the technologies it seeks to deploy but in the assumptions it makes about how we relate to the natural world. Its essence is the idea that it is feasible to control the Earth’s climate. It is a philosophy, then — a philosophy that characterises the problem of climate change as something "solvable" by engineering, rather than a social phenomenon emerging from politics and culture.

Thinking about it in this way — as a set of assumptions about how to tackle climate change rather than a set of technologies — makes it easier to see why the ethical issues embedded in the concept are trickier than any scientific disputes about the side effects of this or that piece of machinery. Here is a project that elevates engineers and their political masters to the status of benevolent deities — "terraformers" we were living in an Scott Card's novel. A project that requires us to manage a suite of world-shaping technologies. Do we have either the desire or the capacity to do that? As the late American climate scientist Stephen Schneider wrote in 2008: "Just imagine if we needed to do all this in 1900 and then the rest of 20th-century history unfolded as it actually did!" In other words, world history is volatile enough even without the question of how to manage the global climate.

These political questions obscure a still deeper issue. If geoengineering involves remaking the global climate, might it also remake the connection between humans and nature?

Sources: Royal Society, University Of Exeter, Guardian, Science, PopSci.

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