Atmospheric Sulphate Injections: blue sky thinking...think again

“The warming of earth by the increasing concentrations of CO2 and other greenhouse gases is partially countered by some backscattering to space of solar radiation by the sulfate particles, which act as cloud condensation nuclei and thereby influence the micro-physical and optical properties of clouds, affecting regional precipitation patterns, and increasing cloud albedo” (Crutzen, 2006).

This form of geoengineering is inspired by observations of volcanic eruptions. By utilising this property of sulphate particles as a form of solar radiation management, we could to cool the planet and offset global warming. However it is important to consider some of the other properties of sulphur dioxide (SO2), which include acid rain, ozone depletion and significant health risks.

“SO2 can affect the respiratory system and the functions of the lungs, and causes irritation of the eyes. Inflammation of the respiratory tract causes coughing, mucus secretion, aggravation of asthma and chronic bronchitis and makes people more prone to infections of the respiratory tract. Hospital admissions for cardiac disease and mortality increase on days with higher SO2 levels. When SO2 combines with water, it forms sulfuric acid; this is the main component of acid rain which is a cause of deforestation.” (WHO, 2011).

The dangers of SO2 mean that there have been considerable efforts and legislation put in place to reduce emissions and this reduction in emissions has to some extent amplified global warming. The situation is something of Catch-22.

The side-effects of atmospheric sulphate injections could include changed precipitation patterns creating pressure on food and water resources, potentially aggravating the risk of famine and drought in areas of the developing world (Tuana et al., 2012)

Atmospheric sulphate injections would also do nothing to combat ocean acidification but would have a negative impact on the production of solar power due to the increase of diffuse light. So while Wigley (2006) stresses the importance of mitigation alongside solar radiation management it seems significant to note that this approach could diminish one carbon-free energy source.

Another impact would be a change in sky colour. Atmospheric sulphate injections would impact the Rayleigh Scattering. Cruzen (2006) describes this impact as “colorful sunsets and sunrises” but others have a less rose-tinted view.

There is a theory that the volcanic eruption of Krakatoa on August 27 1883, which resulted in “Magnificent fiery sunsets and sunrises”, inspired Edvard Munch’s iconic painting “The Scream”. Munch recounts his experience of his inspiration:

"I was walking along the road with two friends—then the Sun set—all at once the sky became blood red—and I felt overcome with melancholy. I stood still and leaned against the railing, dead tired—clouds like blood and tongues of fire hung above the blue-black fjord and the city. My friends went on, and I stood alone, trembling with anxiety. I felt a great, unending scream piercing through nature."

(Olson et al., 2004)

Image Source: Wikipedia.org

Solar Radiation Management

Solar radiation management basically involves increasing the reflectivity of the planet so that less solar radiation is absorbed and the planet is cooler as a result. SRM proposals include:

• Increasing the reflectivity of the planet by painting structures white. This approach is often considered quite benign and would need to be implemented on a massive scale to have a discernible impact.

• Marine cloud brightening. The overall concept here is that albedo of clouds could be increased by making the clouds brighter. One way to do this would be to spray clouds with seawater.

• Atmospheric sulphate injections. This proposal aims to mimic the effect of volcanic eruptions.

• ”Placing shields or deflectors in space to reduce the amount of solar energy reaching the Earth”

(Shepherd, 2012: 4169)

SRM is at the heart of the controversy that surrounds geoengineering. This controversy is for number of reasons, including:

• The ethics of deliberate manipulation of the global climate.

• The military origins and associations with some geoengineering proposals.

• The known side-effects of SRM, which we are aware of and (we think) we understand.

• The side-effects that we do not understand and have not considered, or unknown unknowns (unless you take exception to that phrase).

The above is not an exhaustive list of SRM proposals, but it is representative of the main ideas. SRM proposals are complex and each one has its own advantages and disadvantages that must be carefully considered before ever being implemented.

One of my concerns with SRM is that it does not address the root of the problem: CO2 emissions. So in some regards SRM can be viewed as making an allowance for CO2 emissions to continue. This effort to maintain current energy consumption and pollution creation patterns serves to diminish efforts to tackle the wider causes of global environmental issues, such as unsustainable societal and economic patterns (Corner & Pidgeon, 2010).

Bickel and Lane, in their report, “An Analysis of Climate Engineering as a Response to Climate Change”, seem to view climate engineering as a substitute for reduced emissions. Despite stating in the opening pages that “the reader should not interpret our focus on climate engineering as implying that other responses to climate change are unneeded”, the authors then go on to discuss the “economic freedom” that flourishes under climate engineering options as opposed to emission controls which are portrayed as an “infringement of economic freedom”. This comparison between climate engineering and emission controls serves to directly contravene the idea that geoengineering should only be implemented in conjunction with emission cuts.

If SRM methods were to be employed they could create “an artificial, approximate and potentially delicate balance between continuing increased greenhouse gas concentrations and reduced solar radiation, which would have to be maintained potentially for many centuries” (Shepherd, 2012: 4170).

Because SRM does not address the root of the problem it does not address the consequences of increased CO2 concentrations in the atmosphere, such as ocean acidification. SRM also adds its own side-effects to the mix, including changed precipitation patterns, ozone depletion and reduced potential for solar power (Tuana et al., 2012 / Shepherd, 2012).

The one big draw of SRM proposals is the time frame in which they would work. They could be called upon in an emergency, such as at the brink of a tipping point, and be implemented to relatively quickly reverse some potentially disastrous climate change trajectory (Tuana et al., 2012). The caution to this is that all of the risks and drawbacks of SRM would be diminished in the face of an impending global environmental disaster and so risky and radical policies could be implemented while a vulnerable public are unable to resist. This in some ways echoes Naomi Klein’s Shock Doctrine theory.

I think that solar radiation management merits further research and full public engagement so that if it is ever to be implemented policy makers and the public can have full confidence in the approach or conversely have the knowledge and power to resist its implementation.

Carbon Dioxide Removal: sweeping the problem under an oceanic carpet

As discussed in my previous post, geoengineering can be broadly categorised into Carbon Dioxide Removal (CDR) and Solar Radiation Management (SRM). Some make the distinction that CDR is not true geoengineering since it aims to reverse carbon emissions and so is more like pollution mitigation. However the scale at which CDR would need be implemented and the potential side-effects mean that it raises many of the same concerns as its cousin, SRM. SRM is often presented as the more sinister and risky side of geoengineering, but while CDR might be seen as the lesser of two evils it is far from ideal.   

Examples of carbon dioxide removal include carbon capture and storage (CCS) and air capture (AC). The distinction is that CCS removes CO2 from fixed point sources such as power plants, i.e. before the CO2 has been released to the atmosphere (and so is a form of pollution mitigation), while AC aims to remove CO2 directly from the atmosphere. In order to have a significant impact on global atmospheric CO2 concentrations AC would need to be implemented on a large scale for a long time, which puts it more into the realm of global climate engineering. The thing is however that this AC technology does not currently exist on a commercial scale (Keith et al. 2006).

In either case, supposing that the CO2 can be successfully captured, it needs to be stored and the most frequent suggestion is in the ocean. Oceans already operate as carbon sinks and by absorbing anthropogenic CO2 emissions the oceans may have diminished and disguised the impact of global warming. The Global Carbon Project estimate that 27% of total emissions from human activities during 2003-2012 were absorbed by the ocean sink. For this reason the ocean is central to many CDR proposals.

One suggestion is to store CO2 so deep in the ocean that the low temperature would change the CO2 from a gas to a liquid, which would be more dense than the water and so would remain in storage. Concerns surrounding this approach are that it would alter the chemical composition of the water, resulting in ocean acidification. Ocean acidification has ramifications for marine species and the development of coral, and in turn would impact human societies that subsist from the ocean. There are also concerns about leakage of carbon from these ocean stores (Nevala & Madin, 2008).

Another proposal to increase the absorption of carbon from the atmosphere into the ocean is to fertilise the ocean with nitrogen in order to promote phytoplankon blooms, which would remove carbon from the atmosphere. Once the phytoplankton die, they sink to the ocean depths, along with the carbon they are storing. The concerns with this approach are the scale on which it would have to be implemented to be effective, and again the potential for altering the chemical composition of the ocean is great. Not to mention the other side-effects, such as the promotion of toxic algae blooms. The cons are troubling and difficult to reconcile, particularly since the effectiveness of this approach is far from guaranteed (Nevala & Madin, 2008).

The Ocean Nourishment Corporation (ONC) however, sees so much potential in ocean fertilization that it “is developing its unique patented ocean nourishment technology”

"ONC’s agenda is to assist in providing scalable solutions to global environmental problems including the excess carbon dioxide waste in the atmosphere and its effects on climate security, ocean acidification and the decline of world fisheries from overfishing, poor management and environmental degradation. These are lofty goals and therefore ONC is no ordinary business, our triple bottom line is environment first, social second and economic third."

So the bottom bottom line is economic?

ONC describe Ocean Acidification as an important issue that “is seriously under investigated”. They acknowledge that “work is needed to clarify the processes, to gain a better understanding of what is happening”. They don’t mention if they are undertaking this work.

I think that understanding the issue of ocean acidification should precede research and development into site selection and nutrient delivery technology, but ONC and I must disagree on this point. The priorities of ONC are particularly interesting since ocean acidification has the potential to diminish ocean biodiversity and productivity, which seems directly at odds with the mission of ONC.

The below link highlights why ocean acidification is so troubling and why it could be worth reconsidering the ocean for carbon storage.

20 Facts About Ocean Acidification

Geoengineering by any other name...would be more palatable?

“It would be more literally accurate to rename geo-engineering “smoke and mirrors”, as those are the two most widely discussed measures for managing incoming solar radiation”

The above quote from Joe Romm is taken from an article he wrote in response to a report 

published by geoengineering experts in which they (among other things) attempted to relaunch geoengineering as “climate remediation”. Romm accuses the panel of “inanely and pointlessly” renaming geoengineering with a “nonsensical greenwashing term that simply isn’t going to catch on”. Given that three members of the panel did not agree with the introduction of the term, Romm probably has a point.

It isn't surprising that some proponents of geoengineering would try to turn their hand to marketing when you consider that geoengineering as a term has developed a bad reputation. Keith (2001: 420) proposes that it is a label reserved for “technologically overreaching proposals that are omitted from serious consideration”. Furthermore “the acceptability of geoengineering will be determined as much by social, legal and political issues as by scientific and technical factors” (Shepherd, 2012: 4167) so if geoengineering is ever to be implemented it has some bad press to shake off.

The concerns and issues surrounding geoengineering go deeper than just poor branding. While it would be better to resolve the “scientific and technical factors” before working on the sales pitch it is worth remembering that as a term, geoengineering is broad, contested and ill-defined. For this reason it is worthwhile examining different examples of geoengineering individually, and assessing them on their individual merits and risks.

There are ways of broadly categorising geoengineering. These categories could be science fiction and “all too feasible” (Hamilton, 2013: 2) or they could be grouped from the benign to the reckless. The mainstream categories are carbon dioxide removal (CDR) and solar radiation management (SRM). There is a distinction between the two.

Carbon dioxide removal would address the issue of too much CO2 in the atmosphere and so it gets close to the cause of the problem. It could be argued that it isn’t really climate engineering but is more like “pollution-mitigation” (Keith, 2001: 420).

Conversely solar radiation management addresses the issue of a warming planet; a side-effect of too much CO2. To borrow a much used analogy it deals with a symptom of the illness but not the root cause.  

The significance of this distinction is another issue.

Hamilton, C (2013) Earth Masters Playing God with Climate. Allen & Unwin