Any winning contenders?

This blog has considered a wide variety of Geoengineering options....so what is the verdict? Are any of them a viable option for solving climate change?

Let us firstly look purely at the potential of each option: To compare Geoengineering options, the potential of each proposal to cool the climate is quantified in terms of radiative forcing (RF). RF describes any imbalance in the Earth’s radiation budget that could be caused by human intervention or natural processes. Once a RF is applied, then the Earth’s radiation budget will usually adjust itself and this will be seen through changes in global temperatures. IPCC (2007) states that the present anthropogenic RF is equal to 1.6 Wmˉ². This is the target that many Geoengineering proposals have adopted to counteract. Are any successful? However, what if mitigation continues to be unsuccessful? Lenton and Vaughan (2009) postulate that without mitigation, anthropogenic C02 forcing could reach approximately 7 Wmˉ² by the end of the century. And even with strong mitigation, anthropogenic RF may still exceed 3 Wmˉ². Therefore, which Geoengineering option/options could counteract this?

Placing sun-shades in space ad increasing planetary albedo through the injection of aerosols into the stratosphere are the only two options with the potential to counteract >3 Wmˉ². Moreover, these options could even be scaled up to counteract further anthropogenic RF. The RF potential of enhancing cloud albedo could also achieve 3 Wmˉ² globally, but the effects would be regional and patchy. This is also true for injecting aerosols, depending on when the aerosols are injected. These shortwave measures appear to have the most potential to roughly cancel the anthropogenic C02 RF, as long as strong mitigation measures are also implemented. The remaining measures such as enhancement of the albedo of deserts, urban areas, crops, grasslands etc, could be used in combination and could achieve a partial cancellation of the anthropogenic C02 RF.

Long-wave measures that influence the carbon cycle through the capture of CO2, either by plants, biochar or chemical means, could be used in conjunction to achieve a RF of approximately 2.5 Wmˉ². These options appear to be much more effective compared to ocean fertilisation, where tests have shown that this option only has a RF of 0.23 Wmˉ² (Lenton and Vaughan, 2009).

Figure 1:

So from looking purely from a Geoengineering potential perspective, air capture and storage, the use of sun-shades and stratospheric aerosols, appear to be the options that would induce the greatest radiative forcing...this can be seen in Figure 1. However, what about the risks....While the use of sun-shades and injections of aerosols may have the most potential, they are also the most risky. If deployment is suddenly stopped then rapid warming could occur (Wigley, 2006) (see post: ‘Geoengineering Projects – are they viable of just plain crazy!’). However, carbon cycle engineering carries less risk associated with failure. Therefore, in my opinion, air capture and storage along with afforestation and the use of biochar appears to be the best option. Compared to the remaining Geoengineering proposals, these options are the least risky, and when used in combination could be equally successful as the short-wave options. Moreover, they have the support from the IPCC and afforestion and bio char could also provide other benefits to society not just carbon sequestration. However, their effectiveness is over a long time scale. Furthermore, these options could only counteract 3 Wmˉ² of the anthropogenic C02 RF, what happens if society fails to mitigate emissions? What about the remaining 4 Wmˉ²? This is why many academics are emphasising the need to investigate the option of stratospheric aerosols (Lawrence, 2006; Schneider, 1996; Lenton and Vaughan, 2009; Victor, et al., 2009; Govindasamy and Caldeira, 2000; Matthews and Caldeira, 2007). Even though this option does have a significant risk element, it may be society’s last resort if rapid climate change occurs. The question is, is there any harm in having an insurance policy? Does it mean we will go out and take more risks if we do?

Geoengineering: Ticking timebomb

Hi everybody,

Today I am going to explain my reasoning behind the dramatic title of this blog. When first conducting research into this field I found that many of the academic papers I came across were titled in an equally dramatic manner, the majority of which with rhetorical questions  such as:

•          ‘The Geoengineering Dilemma: To Speak or Not to Speak’ (Lawrence, 2006)
•           ‘Geoengineering climate change: Treating the symptom over the cause’ (Kiehl, 2006)
•           ‘The Geoengineering Option: A Last Resort Against Global Warming’ (Victor, et al., 2009)
•           ‘Geoengineering: Could – Or Should- We do It?’(Schneider, 1996)

This was the first reason for the dramatic title, as right from the onset, even before reading the papers, it can be seen that the topic of Geoengineering is controversial, debatable and is surrounded by ethical and moral issues. Further reading then lead to the creation of the title for this blog as it became apparent that the prospect of Geoengineering could be compared to a ticking timebomb in so many ways: 

1. Even discussing it could have catastrophic impacts as it could cause people to question whether or not they should cut emissions if there are alternate solutions. Therefore even discussing Geoengineering options could give politicians, companies and people an excuse to carry on living their life without fear of the repercussions (Victor, et al., 2009).
2.  Deployment – this has been briefly touched upon in previous posts. Many of the options e.g. ocean fertilisation, enhancing the cloud albedo, injecting aerosols into the atmosphere – these could be carried out by individual countries or even private companies. Therefore, unlike cutting emissions, it does not require a collective effort to be deployed. If one government was to decide they no longer want to cut emissions and that they would prefer to adopt a less costly approach e.g. injecting aerosols (see last post) then they could do so. However, the impacts that this may have are still heavily unknown! (Victor, et al., 2009).
3. It is difficult to police – if a government or private company was to adopt a geoengineering approach e.g. injecting aerosols or enhancing cloud albedo, then it would be difficult to determine who initiated the action (Schneider, 1996).
4.  What is the boundary– unlike testing in other scientific fields that are deemed risky e.g. GM foods or nuclear weapons or nuclear power, although some of the impacts of these activities may be difficult to localise, it is still easier compared to Geoengineering approaches. Where is the line? At what point or amount does injecting aerosols into the atmosphere move from being an experiment, to significantly altering the climate of a region? Ocean fertilisation is easy to limit, but approaches that involve the atmosphere such as injecting aerosols or enhancing cloud albedo, become difficult to limit (Lawrence, 2006).

All of these factors make the Geoengineering field a very dynamic; one that as climate change continues, this field will gain more and more attention. However, to ensure that the negative consequences of Geoengineering do not occur (that the bomb doesn’t go off), a governing body is needed to monitor and regulate all Geoengineering activity. Currently, different projects have captured the attention of different bodies such as the IPCC, US Department of Energy, NASA, UNFCCC, Natural Environment Research Council (NERC) and the Royal Society. This shows that a variety of bodies are interested in Geoengineering, but due to its global nature, an overarching body is required to ensure that the symptom to climate change does not turn out to be worse than the cure.

The Economics behind Geoengineering

Let’s look at the idea of injecting aerosols into space more closely...(Previous posts go into the science, today we will be looking at the cost because as we know money matters!). One of the reasons why research into Geoengineering approaches is on the rise is due to the financial cost of cutting GHG emissions. Could Geoengineering approaches be more cost effective?

David Keith, from the University of Calgary, commissioned a study using a company that makes high-altitude drones. The study showed that small airlines could be newly designed in order to be capable at flying at altitudes of 20-25km and distributing tens of thousands of sulphuric acid vapour. It is estimated that approximately 80 such planes would be required every year to inject the vapour into the atmosphere and cool the Earth by a degree or two. This goal could never be achieved by purely cutting GHG emissions. The planes would have an operational lifetime of 20 years, and would cost approximately one or two billion dollars (Economist, 2010).

The study conducted may be deemed as a breakthrough for such Geoengineering projects...as it proposes that a couple of billion dollars a year spent on sulphur would be enough to offset the warming. If comparing this option with the option of moving to low-carbon energy sources, which would require hundreds of billions of dollars.....then for any politician it’s an easy choice to make! It maybe so easy that the potential risks of the approach could be entirely forgotten!

Locking away the carbon

The IPCC has acknowledged that along with other mitigation options, Carbon Capture and Storage (CCS) could make significant reductions to GHG emissions. Geological storage is the preferred option as there are still large amounts of uncertainty regarding storing CO2 in deep oceans.

Carbon capture firstly involves capturing the CO2 directly from emission sources e.g. power plants and large industrial plants. The C02 is then dehydrated, compressed and transported and then finally injected into a reservoir. The capture and transportation is relatively easy, it is the storage part that is providing an obstacle and is causing concern.

Underground C02 of any kind must take place in sedimentary rock. Figure 1 shows the sedimentary basins of the world where CO2 could potentially be stored. C02 must also be stored deeper than 800m below the surface. Oil fields, gas fields and saline formations have been proposed as storage sites (Marchetti, 1977). Approximately 30 to 50 million metric tonnes of CO₂ are injected annually in the United States into declining oil fields. Both the report from the IPCC and House, et al. (2006) conclude the storage capacity for C02 is expected to exceed available fossil fuel reservoirs. Lenton and Vaughan (2009) postulate that in the long-term, carbon capture and storage could potentially sequester >1000 PgC.

Out of all the Geoengineering options discussed, the option of CCS appears to be the most researched, tested, implemented and supported. The backing and investigation by the IPCC has provided confidence in this option. In 2008, a German Power Plant run by Vattenfall conducted a pilot study through creating a CCS power plant. It was found that this plant reduced emissions of C02 by 80-90% compared to a power plant without CCS (IPCC, 2005). However, as with all of the other Geoengineering options discussed, there are downsides....firstly, capturing and compressing CO2 requires large amounts of energy. The amount of fuel required to operate a CCS plant would need to increase by 25-40% (IPCC, 2005). Secondly, there are numerous health and safety risks regarding storage, and many long-term uncertainties. For example, a big uncertainty regarding the use of deep oceans for C02 storage is the impact that this may have on ocean acidification.

Compared to many of the Geoengineering options investigated, CCS is the first one that I feel confident about. But is this because it has the backing of the IPCC? Compared to the other options were a few academics are leading the research, the IPCC appears to be taking point, bringing a variety of academics together to discuss and research CCS...so maybe Geoengineering is not all bad news!

Biochar? A silver bullet?

Biochar is created through the slow decomposition of organic matter at high temperatures in the absence of oxygen. Normally the organic matter would decompose rapidly after the vegetation/plant matter dies, releasing CO2, however, instead of allowing the plant matter to decompose, the process of pyrolysis can be used to sequester the carbon.

The use of biochar for carbon sequestration is a novel idea (I had never heard of it until I conducted this investigation!) Biochar can draw carbon from the atmosphere, locking it away for thousands of years, making it a long-term carbon sink (Winsley, 2007). Global analysis reveals that approximately 12% of terrestrial carbon emissions could be offset by biochar (Lehmann, et al., 2006). Moreover, by burying the biochar in the soil, this increases the fertility of the soil. Consequently, as with afforestation, the creation of biochar is another option that many land owners and farmers are pursuing as biochar can also be used to earn carbon credits. However, the disadvantage of biochar is that involves burning vast areas of natural habitats and ecosystems. If biochar was heavily integrated into the carbon markets then what would this mean for our natural ecosystems?

When the idea of biochar first came about, many referred to it as the ‘silver bullet’, seeing it as a method to utilise waste in a way that allows society to offset emissions. However, the extent to which emissions are offset is limited. Lenton and Vaughan (2009) suggest that by the 2060s a saturation point will achieved if biochar is fully adopted as a way to sequester carbon. Therefore, this shows that this option is difficult to scale up to a level that will make a significant impact to carbon emissions.

Overall, research shows that biochar can store large amounts of carbon, it is stable and can last a very longtime, so it can even be termed as a ‘permanent’ carbon sink. However, what worries me is the conflicting results found regarding the impact that biochar may have only soil. Some scientists argues that is beneficial and increases the productivity of soil, while others argue that it increases the pH of soil and could be damaging (see video showing experiment with biochar). There is concern that companies may start to heavily invest in biochar through conducting pyrolysis on an industrial scale in order to gain carbon credits. Before this happens we need to ensure we know the effects that biochar will have on our soils; especially since that once it is mixed with the soils, it will be there for a very long time...

Trying the greener option!

While this blog has explored a variety of radical and alternative options, I thought it was time to take a look at a more conservative and greener option: Afforestation. This process, of establishing forests in regions that were not previously forests, sequesters carbon in the biomass of trees. While oceans are considered to be large carbon sinks, forests are also capable of storing relatively large amounts of terrestrial carbon: Occupying one third of the earth, forest vegetation and soils contain approximately 60% of the total terrestrial carbon (Winjum, et al., 1992).

Forest management for carbon sequestration is a low cost, low technology option, which may not stop climate change but will help to mitigate global climate change while more long-term solutions are adopted. It is now being incorporated into policies in the US as forests are now being considered as a source of offsets in carbon markets. Forest management for carbon sequestration also provides an opportunity for land owners to gain a new source of income (Charnley, et al., 2010).

Moore, et al. (2010) argues that that out of the variety of Geoengineering options available, afforestation and forest management is the least risky and most desirable. Chemical carbon capture from air would require an energy source, while ocean fertilisation is less likely to be as effective as terrestrial carbon capture methods and will also be more risky. It is predicted that through the afforestation of regions, CO2 can be reduced by 45ppm by 2060. This may appear minimal but there are numerous other benefits of afforestation e.g. increases in ecosystem richness, water management and providing social amenities. Moreover, the incorporation of afforestation into the carbon markets has yet to be achieved as there are still several questions that need to be answered: What is the management technique that will ensure maximum carbon sequestration? Does this forest management conflict with other aims of forested regions? How do we ensure that all land owners follow the same management practices?

Overall, this option is by far the most safe and the most ‘green’. Consequently, it fits in with many government’s ‘no regrets’ approach to climate change. And despite the fact that it doesn’t reduce C02 emissions significantly, in comparison to other Geoengineering options, afforestation would make the world a much ‘greener’ place...so what is wrong with that?

Other ways to enhance the Earth’s Albedo...

Hi all,

The last post looked at the effects on enhancing the albedo of the earth...however, this is limited to only enhancing the albedo of marine stratiform clouds. This got me thinking about what would be the impact if we increased the albedo of other regions e.g. urban areas and crops

Akbari, et al. (2009) found that by increasing the albedo of urban areas, this could, to some extent, counteract the warming induced by GHG emissions, by increasing the concentration of solar radiation reflected. Through using reflective materials in replace of roofs and pavements (that together make up 60% of urban surfaces) the albedo of urban areas could be increased by 0.1. This would be equivalent to offsetting 44Gt of C02 emissions. At $25 a tonne, this could potentially save $1,100 billion dollars just by changing the albedo of roofs and pavements.

Crops exert an important influence over the climate energy budget because of their difference in albedo compared to soils and natural vegetation. Therefore, one idea proposed is to bio-geoengineer  crops by having specific leaf glossiness to ensure maximum solar reflectance. Ridgwell, et al., (2009) estimates by doing this, temperatures can be reduce by 1°C during summer for much of Central America, if the bio-geoengineered crops are adopted.

Enhancing the albedo of regions will not cause significant changes in temperature, unlike other Geoengineering options, but it will provide society with more time to advance the development and use of low–emission energy and conversion technologies (Hamwey, 2006). Personally, the idea of bio-geoengineering crops sounds a bit scary, as these crops will be then eaten by people, but genetically modifying crops is an idea that has been debated for years, research into whether crops could be modified further could be interesting...However, the idea of increasing the albedo of roofs and pavements does seem more viable...if roofs and pavements were replaced gradually with more reflective material then this could buy us more time, with relatively little inconvenience. Moreover, it would likely cause significant changes to temperatures locally, reducing the urban heat island effect. Overall, it could be a very small step to mitigating global climate change...or would it be an excuse to relax regulations on emissions? To do or not to do...that is the question!

Whitening the atmosphere....

Hey all, so after a week in Greece with leading scientist in the past global and regional climatic change, Mark Maslin, the topic of climate change came up! This coupled with one specific day devoted to understanding micro-climates has inspired the blog post of today!

A couple of years ago, I went to San Francisco. Now seeing how the city is located relatively close to regions such as Los Angeles and Las Vegas, and I was going in summer, I packed very few warm clothes. My family and I realised only after a couple of hours that this was a big mistake. Therefore, we now each have a very warm fleece with a San Francisco label on it that we say we bought as a souvenir on our very first day!. So why am I going down memory lane? And what does this have to do with climate change and micro-climate...well when looking into the concept of micro-climates during the fieldtrip, we learnt the importance of cloud cover and how the concentration of cloud cover influences the amount of solar radiation that reaches the ground. When using this understanding along with typical photos of San Francisco’s Golden Gate Bridge (see Figure 1), the cold temperatures experienced on my summer holiday are now very much understood!

Figure 1:

This brings me on to one geoengineering approach that I have particularly found interesting: the idea of enhancing cloud albedo. The idea that by increasing the white and shiny parts of our earth to increase solar reflectance and reduce temperatures; without severely altering ecosystems or polluting the atmosphere or even crossing the border into space, seems like a wish come true. And people like John Latham put across a very convincing argument!

In the same way that San Francisco has its fog and cloud cover to protect it from the sun, academics such as John Latham and Steven Salter, argue that this idea could be replicated and could influence temperatures on a global scale. Using a fleet of futuristic cloud seeding yachts (see Figure 2) that work by atomising sea water to feed clouds, making them denser and more reflective, the temperature of the earth could be influenced. 

Figure 2:

As the sea water is sprayed into the atmosphere, the freshwater evaporates leaving salt particles which rise into the clouds, attracts water vapour, condenses and increases the density of the clouds. Latham predicts that the warming produced by carbon dioxide emissions could be balanced by 15-20% increases in cloud cover (Latham, 1990). This would roughly equate to 500 litres of water being sprayed into the atmosphere per second, which would require 50 ships to be built per year to keep temperatures stable. This seems doable, especially compared to more radical ideas of solar shades in space.  

So now that we know the science, lets break down this option to see if it is viable solution to climate change?

Advantages: (Latham, 2002)

1. The amount of cooling can be controlled by measuring cloud albedo and using satellites
2. If any unforeseen or adverse impacts occurred, the entire system could be switched off, and cloud properties will return back to normal after a few days
3. This action is benign ecologically and also would not contribute further GHGs

Disadvantages: (Latham, et al.,2008)

1. A lot of further work and understanding is needed
2. Increased water vapour between the oceans and clouds is likely to have a high impact in localized regions
3. If implemented on a global scale, it would result in significant changes to the distribution of temperatures
4. Since the cloud albedo is enhanced only over the oceans, this may result in changes to the land-sea temperature gradient which drives precipitation
5. Unknown climatic impacts e.g on storms

Overall, like with the other Geoengineering options discussed, further work is desperately required (Feingold, et al., 1999). John Latham appears to be spearheading the research in this field, without little opposition or debate regarding the science (He has his name in nearly every paper read on enhancing cloud albedo..the few that exist anyways!). I would feel a lot more comfortable if we threw some more academics into the mix to join in the debate and extend the understanding of what could be a viable option to ameliorate the impacts of climate change!