Geoengineering conspiracies Top Trumps continued...

Algae covered buildings: Algae on buildings could be implemented to actively take up CO2 from the atmosphere. Although it may not be majorly effective, it is worth a thought!

Vertical farming: Food production will allow for the production of crops to meet the planets growing food demand, without the requirement for deforestation as less land would be required for food production.

Artificial trees: Artificial trees would capture CO2 from road sides and secreting them into carbon storage facilities. Although this option would not have a major environmental impact, it may be faily cost effective and is quite a realistic option as the artificial trees could be produced from similar environmental concepts currently out there. 

Geoengineering conspiracies Top Trumps

This and the following blog post will attempt to address some of the crazy and borderline conspiracy geoengineering theories that are to be found from all corners of the web, evaluated in a ‘top-trump’ style review of each engineering method, because, well, why not? Each technique will by rated out of 100 points based on its ability to save the planet, it's cost-effectiveness, it's negative impacts and a realism rating - a higher rating being beneficial for each focus.

Ocean Fertilisation: The dumping of nutrients (e.g. Dust Fe) as a carbon removal option with the intention of this increasing productivity amongst microscopic phytoplankton in the oceans thus increasing the oceans carbon uptake.  

Dam the Med: Introducing a dam in the Mediterranean ocean, which could allow warmer water to circulate towards Canada creating increased snowfall and expanding Canada's diminishing Ice sheets.

Flood Death Valley: Flooding below sea-level Death Valley, and other similar localities could help fight rising sea levels

Wrapping Greenland in reflective blankets: Suggested by glacier expert Dr. Jason Box, wrapping Greenland in a reflective blanket would attempt t reflect more of the sun's energy back into space, thus reducing surface temperatures, allowing for greater control of the Earth's Albedo. 

Hmmm.

Giant Space Mirrors...Science-Fiction or Science-Fantastic?

Generic sci-fi poster

Giant space mirrors. They sound like something out of the latest 'end of the world' sci-fi film that will inevitably collide with an asteroid, sending the object hurtling towards Earth to threaten humanities very existence. 

At least, that's what you'd think...

In 2001, American climate scientist Lowell Wood proposed the insertion of ‘giant space mirrors’ into space to the United States government as a strategy to protect Earth from the worsening impacts of climate change. A giant space mirror would attempt to reduce the solar energy the Earth receives by reflecting solar rays back out to space. It is thought that a space mirror system could weaken global insolation from the solar rays at a rate of 1 W m^-2 per decade. This would increase the Earth’s albedo effect whilst balancing out the impact radiative impact of the planet’s ever increasing greenhouse gas emissions.

A theoretical idea of what a space mirror could look like
http://www.nerc.ac.uk/planetearth/stories/302/

Could it help?

The principle reason for the use of space mirrors is that it could have a very positive effect of limiting sea-level rise. Over 634 million people around the world live in an area of low elevation, including 46% of the population of Bangladesh who live within 10m of sea level. Thus, any impact that a geoengineering scheme can have on limiting sea-level rise may be of undeniable assistance to millions on our planet. 

Is it viable?

When assessing the practicality of this notion, one can quickly realise that the insertion of giant space mirrors is flawed. Firstly, Lowell Wood’s proposed space mirror requires a surface area of 600,000 miles². That's over twice the size of the state of Texas! This staggering assessment then leads to the thought of how costly space mirrors may be. The economic viewpoint is examined well by Takanobu Kosugi. His estimates vary depending on how much the planet would need to be cooled by. By 3ᵒC, costs my exceed $240 billion, however by 6ᵒC costs may be up to $1.9 trillion. Kosugi bases these figures too on the fact that mass production of required space parts would lead to reduced costs, a thought that carries no certainty.

To conclude, although it must be admitted that space mirrors would reduce global temperatures, at a cost of $1.9 trillion, they are certainly not a viable option as they do not address other key climate issues such as ocean acidification. Therefore it is with regret that I must label this geoengineering theory as nothing more than a good bit of science-fiction. 

Carbon Capture...Is it a YES or NO?

In the past two weeks, I have posted blog updates arguing critical points in favour (The great potential of Carbon Capture & Storage) of implementing Carbon Capture and Storage (CCS) as well as arguments against (So CCS isn't perfect either?!) this technology form. Here I shall attempt to evaluate the opposing arguments to determine whether this method of geoengineering is a realistic and viable option to tackle the threats posed by climate change.

Firstly, in terms of mere practicality aspect, there can be an excuse for...dare we say it...optimism. The storage potential for CO₂ within accessible geological formations undoubtedly impressive. Jon Gibbins and Hannah Chalmers' work alone which argues that the UK could use this technology to store forty years’ worth of carbon emissions is worthy of governments offering their attention to this concept. When examining this idea, one must also analyse the environmental risks offered by this method to determine whether this advantage is actually worth it at all.

As outlined in 'So CCS isn't perfect either?!', the threats to the environment through ways such as: CO₂ leaking at the surface and creating a risk of asphyxiation amongst those living close to the source, CO₂ leaking into oceans contributing to the production of carbonic acid further enhancing ocean acidification and the contamination of vital groundwater sources that are used to provide fresh drinking water for many. Therefore if we are to proceed with CCS, I believe that a certain criteria should be met to avoid or at the very least minimalise negative environmental impacts that may be caused. Firstly, the materials used to create transport pipelines and storage facilities must be of the highest quality and be constantly analysed for any potential re-occurring maintenance issues. Storage at onshore localities should be very limited, areas that contain diverse ecosystems should be totally avoided. I also believe there should be further collaboration between researchers, industrial companies and policy-makers to ensure that further testing of limiting CO₂ can be done before any amount of carbon is to be stored beneath the sea. If these points met, then CCS may be a viable option.

However, in refutation of the previous argument, to meet this criteria would impose an even greater financial burden for this technology. It is predicted that per tonne of Carbon removed, the cost would be €60-90, which when taking into account the megatons of carbon that would be abated represents a severe economic investment. Such an investment would no doubt require government subsidies to attract companies to undertake CCS.

Is at all worth it? Are we better suited investing or subsidizing ‘greener’ technologies?



To conclude, I believe that CCS is by no means a perfect solution, and requires further development and investment to ensure it would not hinder environmental processes. However, one must realise that currently (as of 29^th November) CO₂ concentration in the atmosphere is at 403.84ppm, the highest concentration of CO₂ in the atmosphere for 650,000 years. It is also clear that as a society, there will not be a decline in fossil fuel use for considerable time. Taking these thoughts into account I believe that there is hope for CCS as a policy. I’d like to point out the ‘Carbon bathtub’ analogy (fig.1). This analogy allows us to identify that even if we were to cut carbon emissions right now, we still have an atmospheric CO₂ and so we require at least some form of removing current CO₂ from the atmosphere. At this current point, a further enhanced CCS method may be a positive option.  





Fig.1 http://ngm.nationalgeographic.com/big-idea/05/carbon-bath

So CCS isn't perfect either?!

Like many things in life, a world of safe CCS may be too good to be true.

Carbon capture specialist Udayan Singh highlights the key problem areas for CCS: the safe transportation of CO₂ and precise and secure injections of CO₂ into geological formations. If this method is to be introduced there will be great pressure on the quality and constant maintenance of carbon pipelines and injection, as leaks could cause vast environmental damage and would prove very costly.

The devastation of the Lake Nyos disaster
http://www.emigennis.com/2014/04/06/lake-nyos-disaster-reference-photos/

Forgarty & McCally state that if CO₂ concentrations were to reach 7%, enough carbon would be present in the blood of humans to cause narcosis and eventually asphyxiation. To support their points, they offer the Lake Nyos, Cameroon 1986 case study. 100,000 tonnes of CO₂ was released as an overturn of a volcanic lake (near Lake Nyo, as described by Damel et al) as the bottom part became over saturated with CO­₂, Holloway importantly claimed that this was due to a slow leak of CO₂ from magmatic sources into the lake. The leak resulted in  carbon concentrations of up to 10% in surrounding areas and consequentially over 1700 people died whilst hundreds contracted skin conditions or suffered from memory loss. This volume of CO₂ equates to seven days of CO₂ emissions from a single coal-fired power plant, and shows just how catastrophically dangerous this technique may have the potential to be. Pro-CCS scientists argue that this singular event cannot form the basis for summarising the risks associated with CO₂ leakage from a geological formation, however, as CO₂ is heavier than surrounding air it accumulates readily in depressions such as lakes. Therefore I believe that this case study does provide strong and accountable evidence for the dangers faced by carbon capture, and it insists that serious considerations need to be introduced before CCS is implemented worldwide.

Additionally, another potentially severe environmental risk caused by CCS is the potential for ocean acidification caused by leaked CO­₂. Ocean acidification is caused by carbon dioxide reacting with the ocean to create carbonic acid (CO₂ + H₂O à H₂CO₃). The ocean represents the planets largest carbon sink, an increase in carbonic acid severely threatens carbonate secreting organisms in the ocean and in doing so reduces the oceans capacity for carbon storage and so more CO₂ is released into the atmosphere and in doing so worsening the greenhouse effect. 

Moreover, Forgarty & McCally point out that ocean acidification can cause an increase of contaminant (e.g. Arsenic and lead) leaching which would endanger the lives of countless species. Furthermore, Holloway (1996) argues that as well as oceans, groundwater located (100-200m below the surface) may be contaminated from CO_2­ leakage. CO₂ groundwater contamination may cause increases in water hardness as well as transforming the concentrations of trace elements present in the water and therefore has seriously negative effects on our drinking water aquifers.

Finally, there is much discussion within the scientific regarding induced seismicity caused by the injection of CO₂ into the ground. Environmental scientists Verdon & Stork state that large volumes of CO₂ injected into a geological reservoir increases the pore pressure of the reservoir rock, which increases the chance of rock failure. Holloway importantly argues that this could result in micro-seismicity or activating previous faults which may trigger earth tremors. Seismic events within reservoirs could damage cap rocks, natural springs or open up faults allowing for CO₂ leakage further damages to other parts of the environment, environmental effects described above can impact the plant. 

Through my research into the risks associated with CCS, it is absolutely clear that this climate mitigation method is not perfect, and requires serious evaluation as to whether these risks can be limited or if the method is even viable at all in sight of these concerns. Luckily for you, I’ll be doing this in my next blog post!

The great potential of Carbon Capture & Storage

Carbon emissions reductions

This year, British home secretary Amber Rudd committed the UK to the ‘fifth carbon budget’, which binds the nation to a maximum CO₂ output between the years 2028-2032 of 1,725 MtCO₂e. Currently, it is thought by many that the UK will not meet this target without substantial changes to energy policy. CCS has a potential to account for 17% of necessary the nations carbon emissions reductions, and so would offer great support for the British energy industry as it may mean that there wouldn’t be a need for such a rapid switch to renewable energies which would inevitably be very costly.

Storage potential

There appears to be a vast storage potential for CO₂ within the Earth, but due to the numerous types of geological formations, the planet’s potential is difficult to estimate. Scientist Udayan Singh reports on IPCC suggestions that there may be the opportunity to store 2000Gt of CO₂ within the planets formations. Further investigations into this reveal that between 675-900 Gt of CO₂ could be stored into oil and gas fields, 1000-10,000 Gt of CO_2­ may be contained in saline formations and between 3-200 Gt of CO­₂ within coal beds. Udayan Singh importantly points out that in 2010, annual global CO₂ emissions were less than 34 Gt of CO₂, thus clearly demonstrating that the world can take confidence in this environmental policy. In addition it is also important to note that as our fossil fuel consumption increases, more space in geological formations for CO₂ storage will become readily available.

Key carbon storage examples:  UK & India case studies

In terms of the UK’s personal environmental policy, Jon Gibbins and Hannah Chalmers predict the UK offshore CO₂ storage potential to be at least 20 Gt of CO₂. This type of formation alone could store the UK’s CO₂ emissions for 40 years!

Fig. 1 - A geological map of India, showing the presence of basaltic rocks
as well as highlighting regions of good, limited or fair storage potential
https://hub.globalccsinstitute.com/publications/regional-assessment-potential-co2-storage-indian-subcontinent/22-potential-geological

Researchers Udayan Singh also reveals information regarding the storage potential of India (the world’s third largest CO₂ producer) and combined their research with McGrail et al’s laboratory experiments to conclude that India alone has an incredible potential for CO₂ storage within onshore and offshore saline aquifers (360 Gt) and within Basaltic rock settings (200 Gt). McGrail et al’s tests revealed that the basalts within the region showed fast chemical reactions with CO₂-saturated water, enabling it to produce stable carbonate minerals. When analysing fig 1, one can realise that due to the vast quantities of basaltic rock within India (formed as a result of the Deccan Traps eruptions which produced material that covers 500,000km² of India’s Western provinces), India’s storage potential within this type of geological formation, and future potential after further scientific research into this field is immense.

Another advantage which would result from storing CO₂ within depleted oil and gas fields is that it will allow for the  recovery of further oil and gas that was not initially recovered for a variety of reasons, for example because it was not initially economically viable. CO₂ also has many industrial purposes, and is used in pharmaceutical, fertilizer and beverage carbonation industries (Udayan Singh).

These methods provide further advantages, as pumping CO₂ into oil fields can also help to retrieve more fuels that were not recovered during initial oil exploration. This is due to the fact that CO₂  injection reduces the viscosity of oil, thus improving the ability of oil  to flow up boreholes to the surface.Whilst in basalt formations, CO₂ reacts with the basalt to form carbonate minerals, further adding to the stability of the formation.

Economic incentives

An interesting economic incentive to carbon capturing is the emission trading mechanism, which limits a country to a maximum volume of CO₂ that can be emitted. However if a country to reduce its emissions below the maximum amount, they would be able to use the CO₂ as a commodity which they could then use in trading and thus generate profits from. This offers yet another advantage for Less Economically Developed Countries, who may not otherwise prioritise emission reductions due to their respective financial situations.

Furthermore, the UK government reports that should CCS be fully implemented into power plants that produce electricity for domestic use, energy prices for citizens would decrease by up to £0.02 per Kilowatt hour (Kwh) by 2030 (fig.2). Correlating this to the whole UK population would show significant energy savings nationally. 

Fig. 2 - A chart expressing future energy savings (in pence per Kwh) per year
with CCS implementation.
https://www.tuc.org.uk/sites/default/files/carboncapturebenefits.pdf

Therefore one can conclude by realising that there is a great potential for CCS, with positive practical and economic aspects, what now needs to be decided is whether these positives outweigh negative issues, which will be talked about in the next blog post.

Another option: Carbon Capture & Storage

What does it entail?

Carbon Capture & Storage (CCS) is defined by the Intergovernmental Panel on Climate Change's (IPCC) Special Report on Carbon Dioxide Capture and Storage as a “process consisting of the separation of CO₂ from industrial and energy-related sources, transport to a storage location and long-term isolation from the atmosphere”. Energy policy experts John Gibbins & Hannah Chalmers offer insights into the three types of carbon separation: post-combustion, pre-combustion and oxyfuel combustion.

Post-combustion capture aims to remove CO₂ just before emission into the atmosphere. An aqueous amine solvent is used to remove the CO₂ from the waste gas at a temperature of approximately 50ᵒC. This solvent can then be re-created for later use by heating it to approximately 120ᵒC before further cooling and recycling. The captured CO₂ is dehydrated and compressed before being transferred to a safe geological storage facility.

Pre-combustion capture involves reforming fossil-fuels with sub-stoichiometric volumes of oxygen at high pressures of approximately 30-70 atmospheres creating a synthesis gas which consists of CO and H₂. Steam is then added before the temperature is reduced to allow for the conversion of CO to CO₂. The CO₂ can then be captured, leaving a Hydrogen-rich gas, as through the use of a physical solvent the CO₂ can be dissolved at higher pressure before being released as the pressure in the system is reduced. Following this, the gas dehydrated and compressed for transporting to a storage site. This method does not require heat to separate and capture the CO₂, and therefore has an advantage over the post-combustion method as it requires less energy for the process to function.

Yukun Hu offers important information on the final process, oxyfuel separation. This method begins by adapting the combustion chamber so that it is filled with almost-pure oxygen using an air separation unit. The fossil fuel is then burnt within the oxygen and a mixture of recycled flue gases which are used as a replacement for Nitrogen (which the carbon would usually burn with in the atmosphere). This produces CO₂ and water vapour which is cleaned and separated during the dehydration and compression processes. Key advantages to this process compared with the other carbon capture methods include the lowest level of CO₂ emissions for all three processes, lower fuel consumptions as well as having the highest combustion efficiency.

Diagram illustrating the processes that take place during the different types of carbon captures.

Transportation:

Unlike the capture methods, there is a fairly unanimous opinion on the best ways to transport captured CO₂. As explained in the IPCC's report, if the gas is only being transported relatively short distances, ships or large vehicles are preferred. However if there is a large transporting distance to the storage site, e.g. thousands of kilometres, then pipelines would be the favoured option. This method of carbon transport is currently in use in nations such as the USA, who have pipelines transporting 40Mt CO₂ over 2,500km every year.

Storage:

Cross-section of a carbon capture storage site, including a
 water-filled reservoir (e.g. Sandstone), cap-rock (e.g. Basalt)
and Oil and Gas fields.
http://www.glossary.oilfield.slb.com/Terms/c/cap_rock.aspx

Favourable geological sites for carbon storage include both onshore and offshore oil and gas fields, Basalt formations, unamenable coal seams and deep saline aquifers. A key requirement for a storage site is depth. To create an optimum density (500kg/m³) for storage, a depth of 1km is needed. Furthermore, a cap-rock (an impenetrable, hard rock which prevents the escape of materials such as oil and gases from escaping to the surface)  would also be required to ensure that the CO₂ can actually be stored underground. 

Although the scientific methods and reasoning behind CCS appear to be reasonable on a practicality level, there remains many further advantageous and problematic aspects to this option will be discussed in the coming blog posts. 

Analysing SPICE

No…not that kind of SPICE…

SPICE refers to the Stratospheric Particle Injection for Climate Engineering project. This was a motion created by a collaboration of minds from the University of Cambridge, Oxford, Bristol and Edinburgh, set up to investigate the benefits, risks, costs and practicality of injecting sulfur aerosols into the atmosphere as a geoengineering method to control the effects of global warming.

This project is of specific interest because it is unique in not only investigating the effectiveness of sulphur in the environment but also researching into public opinion surrounding this form of Solar Radiation Management. If public opinion were not to be on side, this form of geoengineering is unlikely to ever become part of world’s environmental policy. SPICE carried out three workshops, in Cardiff, Norwich and Nottingham with a wide demographic of personnel in an attempt to understand genuine public perception of geoengineering. Several controls were made, such as attempting not to overload participants with too much information as to prevent deterring the development of their natural thoughts. At the workshops, researchers offered background information on climate change and the current challenges being faced before describing the specific method of SRM so that the participants could develop a reasonable understanding from which they could develop their own conclusions on the matter.  Researches then explained that sulfur aerosols would be injected into the stratosphere via a 20km pipeline, as this may be the most cost-effective and environmentally-effective way of releasing the aerosol. Participants were then told that a 1km ‘test-bed including scaled-down versions of the tether, balloon and pumping system will be designed and constructed’ to give geoengineering researchers greater knowledge of the functionality of a tethered balloon within various weather systems as well as to allow for an improved understanding of the scattering of pumped particles.

The response:

“The only thing is when you put in the money it would take to set up those schemes to get that short-term gain, that could be money going into actually solving the problem, I think that’s where the issue is. That’s why it feels like it’s cheating as I said” (Laurel, Norwich).

The public workshop groups discovered a consistent and coherent  response from each group, a view that SRM is not actually solving the original problem, and is instead just treating the symptoms of the issue and that financial resources should be spent tackling emission issues head on. Furthermore, although the participants welcomed the test-bed for sulfur injection, there still remained many concerns over the practicality of aerosol injection. Primary issues were based upon where the injection would take place, with participants stating that they would not want this process occurring near their local areas, and the need for transparency amongst the research process, testing and the executing the policy.

This data poses yet another stumbling block for aerosol injection as it is clear through this research that currently, public opinion is not in favour of this method. This is majorly significant as with such doubts about this method across the nation, governments are less likely to support this environmental policy in fear of political backlashes, and thus poses severe doubts over the realistic chances of this method ever becoming practically developed. 

Hang on, there are downsides to Solar Radiation Management? Like an environmentalist once said, ain't that a kick in the head...

Dean Martin captured on a rumoured SRM flight mission 

In total, 240W of sunlight per square metre is absorbed by earth and is the principle method of how the Earth natural maintains or increases its temperature. Since the beginning of the industrial revolution, atmospheric CO₂ has almost doubled to 401.1ppm and at current trajectories is predicted to surpass the 450ppm ‘tipping point’ in which issues including ocean acidification and temperature increases may become so critical that they pass the point where by which they are salvageable. 

Caldeira writes that the doubling atmospheric CO₂ results in a radiative forcing of approximately 4Wm^-2. He then states that as a percentage of sunlight absorbed by the Earth per square metre, 1.7% of incoming solar radiation would need to be prevented from reaching the Earth’s surface to minimalise temperature rises. Thus, one would think that limiting this sunlight could help limit global warming. Enter, solar radiation management (SRM) – specifically Sulfur aerosols. For a detailed insight into the specifics behind this technique, see last weeks blog post.

So there you have it, a miraculous cure to save the planet from the impending doom of climate change. Well, not quite. Just like most quick-fixes, there are numerous severe stumbling blocks of this scenario, such as: resultant effects on regional climate; continued ocean acidification; the effects on clouds and the consideration about what happens if we change our mind and wish to stop this approach.

Oh, the weather outside is frightful…

A map of East Asia showing which areas are effected  by
reductions in precipitation, and by how much  (measured in mm).
http://onlinelibrary.wiley.com/doi/10.1111/j.1600-0889.2009.00427.x/pdf

Alan Robock identifies a link between large volcanic eruptions and weakening African and Asian monsoons. In addition, Robock also points out the link between the eruption at Lake Fissure (Iceland) between 1783-84 and the following reduction of precipitation in Africa, Asia and Japan which resulted in the a famine responsible for the deaths of 25% of the Egyptian population.

S. Tilmes et al takes Robock's link further by discuss climate model experiments which have been used to simulate the consequences of Sulfur aerosol injections. They also write that when testing effects on regional weather systems with atmospheric CO₂ at pre-industrial levels that would result from SRM, there are significant impacts on precipitation and evaporation predominantly in the tropics and mid-latitude regions. They discovered a decrease in a mean precipitation of 3.6% over land. Specifically, the region hit with the greatest reductions in monsoon precipitation are East Asia (by 6%). This impact is extremely worrying as it would result in reduced yields for important crops in this region, leading to food shortages and a worsened quality of life for up to 1.5 billion people that live in this region. Thus, in light of this potential hydrological impact one could argue that it may be immoral to injection sulfate aerosol . 

When the world starts to shine like its had too much wine...it may be because Sulfer Aerosols offer no help with regards to the problem of ocean acidification

Up to 33% of Carbon Dioxide emissions from the human combustion of fossil fuels is absorbed by the ocean consequentially resulting in ocean acidification. As CO₂ is absorbed by the ocean it reacts with water to form Carbonic acid (H₂CO₃). This Carbonic acid dissociates within the water to produce bicarbonates releasing Hydrogen ions, hence causing an increase in acidification. The knock-on effect of this is that it would reduce the amount of carbon that could be stored in the oceans, which are the world's largest carbon sinks. doing so cause further global warming. Aerosol interjection offers no relief for this issue and would only allow this issue to worsen.

Everybody loves somebody...unless Sulfur aerosols divide international communities and starts a world war

Robock shines light on the political complexities tied to this stream of geoengineering. If an event were to happen, for example a world war, the aerosol injection programme would become seriously hindered. If there were to be a sudden halt to sulfur injections then we would see rapid global warming due to fact that greenhouse gas levels would have continued rising at exponential rates. Environmentalists such as Caldiera argue a rapid global warming process would cause exceedingly more damage to the worlds ecosystems than a more gradual global warming that we see happening today.

Furthermore, Robock suggests that if we were to proceed with this process, how do nations decide on whether a specific region such as East Asia should have to absorb the potential harsh impacts of this whilst other regions are relatively unscathed? This is an extremely valid point raised, and leads one to hypothetically argue that this could one day present the grounds for conflict itself if a nation being unfairly subjected to man-induced environmental alterations was rise up and fight against the environmental predicament that they had found themselves in. Therefore we must ask ourselves whether we would be truly comfortable with a global warming quick-fix that has the potential to one day be a proxy for future global conflicts.

In conclusion, although the analysis in last weeks blog post does suggest that injecting sulfate aerosols into the atmosphere would cool the Earth and restrict global warming. I feel that upon evaluating the side-effects and political uncertainties of this method, global governments should not seek to implement this form of geoengineering. Instead, we should investigate further other forms of geoengineering, such as solar mirrors or perhaps Carbon Capture and Storage. Both of which will be discussed in the continuation of this blog.

A deodorant to save planet Earth...no, really?!

Well, not exactly Lynx Chocolate (other products are available), but many important environmental scientists including Paul J. Crutzen and Philip J. Rasch have discussed injecting aerosols into the atmosphere in an attempt to prevent UV radiation from the sun from striking the Earth’s surface and warming the planet. A key concept with regard to controlling the Earth’s surface temperature is the planet's radiative balance. This is the balance between energy hitting the earth from the sun and outgoing thermal (longwave) and reflected (shortwave) energy. If one side of this balance outweighs the other, for example if there is an unbalanced increase in reflected shortwave energy, then effectively the Earth’s albedo will be enhanced causing a cooler planet. This then leads one to the thought that what if mankind could develop a way of controlling the earth’s radiation balance within the Earth's atmosphere and use this to tackle climate change? Enter, Solar radiation management (SRM). 

Who to thank for such an atmospheric rise (pardon the pun) in environmental thinking …Volcanoes!

The famous eruption of Mount Pinatubo (12/06/1991)
http://volquake.weebly.com/mt-pinatubo-1991.html

This type of geoengineering has long been inspired by volcanoes. During large volcanic eruptions, immense volumes of SO₂ emitted and are converted into Sulfate aerosols in the atmosphere, which then reflect and absorb infrared energy whilst emitting long-wave radiation. On 12^th June 1991, Mount Pinatubo in the Philippines erupted producing the greatest aerosol cloud of the century. Crutzen states that as a result of this eruption, 10TgS of SO₂ was emitted into the stratosphere. The stratosphere (the second layer of the atmosphere, encompassing area 12-50km above the Earth's surface) is the most significant layer of the atmosphere with regards to the planets radiative balance, as not only does this layer contain the ozone layer, but also in the stratosphere sulfate aerosols have long residence time of 1-2 years. In comparison, the troposphere (the first layer of the atmosphere, located below the stratosphere) only has a sulfate aerosol residence time of a few days. This volcanic event initiated the cooling of the Earth by 0.5ᵒC for the following year and thus offered greater hope for the success of SRM as a means for geoengineering.

This notion poses perhaps even more questions, such as: What type of aerosol would we inject into the atmosphere? What quantity of aerosol would be required and where should this be distributed?

Rasch et al state that the most favoured way of injecting sulfate aerosols into the atmosphere are via precursor sulfide gases, such as sulfuric acid, Hydrogen Sulfide (H₂S) and Sulfur Dioxide (SO₂). These precursors become oxidised to end products which importantly contain the Sulfate anion (SO₄^-2). The majority of stratospheric sulfate aerosols undergo further oxidation to form an assortment of Sulfuric acid, water and nitric acid hydrates. A perilous aspect of this task is determining just how much aerosol would be required to reduce global temperatures. Using the effects of the Mount Pinatubo eruption to model SRM, geophysicist James Hansen calculated that this eruption resulted in a radiative cooling of approximately -4.5W/m² caused by 6TgS that remained in the stratosphere six months after the first eruption. This gives a 75% cooling efficiency which offers a basis for suggesting an aerosol quantity that would be required to restrict the Earth's temperature.

This figure shows the widening gap between 'natural and human factors' and 'natural factors
only' for global temperature changes, expressing the clear relationship between human impacts
and global temperature change.
https://www.epa.gov/sites/production/files/2016-07/models-observed-human-natural.png

When analysing the difference between human and natural influences on climate, there is a clear temperature gap of approximately 1.2ᵒC. To reduce temperatures by 1.2ᵒC a radiative cooling of -10.8W/m² is required. When equating this to a sulfate aerosol volume, using a cooling efficiency of 75% we would require 14.4TgS to be emitted into the Stratosphere. However, this would be the upper limit of the amount of aerosol that would be required. This is because sulfur from anthropological aerosols differ to volcanic sulfur particles, they are finer and have a longer residence time. Thus, less than 14.4TgS would actually be required. However, one must also realise that by the time that a form of SRM could be implemented, global temperatures would be even greater than the present day and thus more Sulfate would actually be required. Although this is a huge amount of sulfur, it is still comfortably within the total amount of sulfate that is created every year throughout the world for various purposes. Therefore one can realise that little extra effort would actually be required to meet this increased sulfur demand.

Practical or impractical?...How do we actually inject aerosols into the stratosphere?

An initial idea for ejecting aerosol into the atmosphere was to release Carbonyl Sulfide (COS) from the earth’s surface. COS is thought to be a principle source of sulfur in the stratosphere that is emitted from low activity volcanoes. The stumbling block for this idea is exposed by Crutzen , where he points out that of the total amount of COS emitted into the atmosphere, approximately 74% is absorbed by plants, 21% removed by reactions with OH in the troposphere leaving only 5% of the emitted COS to reach the stratosphere. Therefore when reviewing this option, to make it a successful sulfur pre-cursor it would have to be developed photochemically in the stratosphere to produce sulfate aerosols. Bearing in mind that this gas would also need to have a long residence time whilst being nonreactive with OH^- it appears that this concept for aerosol distribution seems some what implausible at the moment.

Future testing for developing techniques to eject aerosol into the atmosphere seem to point towards the use of high altitude military jets which would have aerosol ejecting features attached to them. This option poses political issues, as questions such as who’s military equipment are to be used? As well as who would be funding this? Questions which are likely to be unanswered for a considerable time.

To conclude, there remains great potential for injecting sulfur aerosols into the environment as a means of increasing the earth’s albedo, as volcanic evidence proves that this model can work. Key difficulties which must be addressed include configuring a definitive sulfur gas pre-cursor to be emitted into the stratosphere as well as deciding how to best deliver the aerosol into the stratosphere. Nevertheless, the overriding factors determining whether this form of geoengineering will ever be introduced will likely be the predicted costs and environmental impacts. Both issues will be discussed in next weeks blog post…

An introduction to the debate



This figure depicts CO₂ increases over the past six years.
Perhaps the most striking part of this graph is that up until
August, 2016 shows the largest CO₂ increases.

On 22^nd April 2016, otherwise known as international ‘Earth Day’, the Paris Agreement was signed by nations across the world symbolising their commitment to the United Nation’s Framework Convention on Climate Change (UNFCC). The quintessential intention of this agreement is to force governments to adapt new policies to eventually limit global temperatures below 2ᵒC above pre-industrial levels by the end of the century in an attempt to avoid irreversible environmental impacts to the planet.



Firstly, when analysing the current environmental trends caused by human activities, it becomes apparent that in order to achieve the targets set out by the Paris Agreement, fundamental energy policies and technologies must be rapidly adapted. As depicted in figure 1, atmospheric Carbon Dioxide levels have moved past 400ppm and are constantly rising, principally caused by the incomplete combustion of Carboniferous fossil fuels to feed mankind’s ridiculous energy requirement.







This figure shoes the exponential increases in energy
usage respective to different energy sources. Here we
can identify that world energy consumption is incredibly
 reliant on unsustainable resources (Coal, Oil and Natural Gas)
www.financialsense.com/node/7827

When analysing the uptake of our most common fossil fuels (Coal, Oil and Natural Gas), an inevitable issue is exposed. Our fossil fuel consumption is increasing at a frighteningly unsustainable level leaving nations increasingly dependent on sources of energy that are becoming ever more sparse. Figure 2 represents the surreal energy gaps between fossil fuels and more sustainable energy sources such as Hydro-electric and Biofuels as a total of world energy consumption.



Subsequently, the issues raised at the start of this blog lead us to the principal theme of my future blog posts. In a world where sudden changes are required to not only meet international frameworks, but to ensure that irreversible and deadly changes to our planet do not occur, what choices are humans, effectively the navigators of the modern earth left with? Do we immediately invest mass financial support into the development of renewable energies whilst risking a threatening energy gap between production and consumption? Or do we look to new innovations in an attempt to micromanage the perplexing systems of the Earth i.e. Geoengineering? Geoengineering is  described by scientist W. Burns as the “deliberate large-scale manipulation of the planetary environment to counteract anthropogenic climate change". Fundamentally, geoengineering breaks down into two paths, either removing Greenhouse Gases (GHGs) from the atmosphere, or by the use of Solar Radiation Management (SRM). Following blog posts will examine scientific reports on key examples of geoengineering, evaluating whether these innovations are both practical and an appropriate allocation of funds to ensure that we can effectively fight climate change.

Personally, at this stage I hold a hesitant view of Geoengineering and am a firm believer that the British government should be investing significantly more into renewable industries today. However, my natural scientific curiosity ensures that I am amenable to the idea of other measures of controlling the planet as it is clear that due to climate change being such a problematic issue, there will not be one sole cure and therefore we must show adaptability to new ideas and cunning concepts to save the Earth.