Plan B?

As this term draw to a close, the question still remains: Is geoengineering a plan b for climate change?

Before I started this blog, I had a rough idea what geoengineering was, but without detailed knowledge on particular methods. In the course of the last three month I read and wrote about cloud seeding by spaying seawater, planting trees, stratospheric sulphur injections, ocean fertilisation and space sunshades. These are all very different methods with different side effects. However, they have two thing in common: The aim to change the environment and the climate on a global scale. Moreover, further research is needed, to be certain what impacts these methods will have. I am not sure we will ever know these impacts for sure if we do not try it out. But is that the best way? How much risk are we willing to take? It is obvious, that geoengineering alone cannot be the solution of our problems. We need to reduce our greenhouse gas emissions on any account. There is no way around that! Something has to be done, but I think we should be very cautious with those methods that hold the greatest uncertainties.

What do you think? Is there a particular method you think could work or is geoengineering not the right way to deal with our problems? I personally think, some of the less radical methods (e.g. seawater spraying to form clouds) could help to mitigate climate change, but first we really do need to know a little bit more about the consequences. However, on a long term only reducing emissions will help, there is no way around that!

Was Durban a success?

'Q&A: Why Durban is different to climate change agreements of the past'

The Guardian published a nice article on the outcome of the Durban climate change conference, in the form of questions and answers on what happend before, what the participants agreed on and what will happen next. It gives a short overview over a really sensitive issue.

In a last minute compromise, the participants agreed on setting up a new agreement on cutting down greenhouse gas emissions. For the first time developed as well as developing countries are included. The agreement is supposed to come into force in 2020. Furthermore this agreement should also be legally binding, making it more difficult for governments to just 'wriggle out' of the treaty. However, the exact goals of how far emission will be reduced are not yet clear and further negotiations will take place until 2015. Therefore it remains to be seen how efficient this agreement will really be.

Read this article online:
http://www.guardian.co.uk/environment/2011/dec/11/durban-questions-and-answers

The Guardian also has several other articles on the conference in Durban:
http://www.guardian.co.uk/environment/durban-climate-change-conference-2011

And this is the official website of COP17/CPM7 in Durban:
http://www.cop17-cmp7durban.com/

Are space sunshades the solution?

Another suggested way to mitigate global warming is using small spacecrafts, placed between Earth and sun as a ‘sunshade for the earth’. This method is analysed in an article by Roger Angel (2006). The idea comes from observations of great volcanic events, after which particles in the atmosphere lead to a cooling effect by scattering and reflecting sunlight. The same idea was used for the sulphur injections, which I described before. However, shielding the earth with space sunshades does not have the same negative side effects for the environment that sulphur has. 

The proposed location for the sunshade is near the Earth-sun inner Lagrange point (L1), which is a point between sun and Earth where theoretically gravity alone makes sure the sunshade remains stationary. The penumbra of the sunshade would cover the whole Earth in this position. However, little spacecrafts rather than just particles are necessary to stay in one formation.

The advantage of this technology is, that neither ocean nor atmosphere is modified, which makes this method more environmentally friendly. Furthermore Angel (2006) argues, that the results are easier to predict than the results for other methods, as only one factor (solar radiation) is changed.

The downside is, that it requires a sunshade at a really large scale, which is not only difficult to achieve technically but is also very expensive.

(source: Angel 2006: 17184)

 The idea is to launch many individual ‘flyers’ (Angel 2006) from the Earth. This way there is no need for a single large sunshade. Still there is a very high cost for transportation. Angel (2006) estimates it to be $50/kg. The whole project would have a cost of 1 trillion $, with a cost average of 100 billion/year (‘0.2% of current world gross domestic product’ Angel 2006: 17189). Also it is not enough to just bring the flyers away from the atmosphere. Additional energy is needed to reach the final location. An optimistic goal is that the flyers will stay in place for approximately 50 years, if the technology is improved further and works as ideal as it is hoped. After this they have to be replaces, but a life period for several decades would be a great achievement compared to other techniques. Angel (2006) further suggests that 20 launchers are needed, each launching 20 million flyers, one every 5 minutes. Launching the flyers obviously requires energy, but the positive effect they have once they reach their destination outweighs this negative on climate.

To sum it up, a cloud of small sunshade has the potential to mitigate the current trend of global warming by scattering incoming solar radiation. The environmental impacts, apart from the energy that is needed to produce and launch the flyers, are by far smaller than the impacts of e.g. ocean fertilization or sulphur injections, which makes the idea even more interesting.

However, this is one of the methods with the highest technological level and very high costs. Even if the costs can be reduced to the goal of 50$/kg with more research, the method is still more expensive than most other geoengineering ideas. Therefore I think, that even if the methods works good in theory, the high costs could be the reason why governments might not want to use it. Another question is, how big are the cost if we do nothing? Adaptation to climate change later might be even more expensive, than trying to mitigate it now. So, shouldn’t we make an efforts to raise the money for geoengineering now, rather than paying for the consequences later?

Literature:

Angel, R. (2006) ‘Feasibility of cooling the Earth with a cloud of small spacecraft near the inner Lagrange point (L1)’ PNAS, 103, 46, 17184-17189.
available online: http://www.pnas.org/content/103/46/17184.full.pdf

Ocean Iron Fertilisation

Today’s article deals with another geoengineering method: Ocean fertilization. These methods try to enhance the sequestration of CO₂, by releasing specific nutrients, especially iron into the oceans on a large-scale. The article by Cullen and Boyd (2008) investigates the consequences of ocean iron fertilisation (OIF). As this is another large-scale method, it also has large-scale consequences that have to be considered.

Studies have shown that fertilisation in HNLC regions (high-nitrate and low-chlorophyll, approximately 30% of the world’s oceans) could sequester 0.5 Gt of carbon per year. An even better rate could be achieved in oligotrophic waters by stimulating primary productivity of phytoplankton. However, using OIF leads to large-scale changes in ocean chemistry and the ocean ecosystem. The changes also occur over a long period of time, as the OIF is supposed to work in a scale of at least a hundred years.

The application of iron to the ocean directly leads to an increase in phytoplankton and thereby to an increased production of organic matter, which then sinks into deeper ocean levels. It is important that the sequestered CO₂ remains in the ocean over a longer period of time, which means it has to stay in depth below the zone where winter mixing occurs. Only the CO₂ that reaches deep waters can be seen as sequestered. However, a certain part will not reach this depth and can still affect the surface layer with increased availability of nutrients, inorganic C and an oxygen deficiency. Therefore processes in mid-depth water still need to be studies in more detail.

As a side effect the production of DMS (dimethylsulfite), which is a source of atmospheric sulfur, can be enhanced. As discussed in a previous post, sulfur can lead to cloud formation and thereby enhance albedo, which is another positive effect in terms of climate change mitigation.

With the increased availability of iron more of the macronutrients in the surface layer of the ocean can be used. This in turn leads to a change in the nutrient composition, which can later on lead to a limitation of further primary production. This again can have impacts e.g. on fishing resources.

As another downstream effect OIF could release N₂O and methane, which are even more potent greenhouse gases than CO₂.

Changes in source water in coastal areas can either have positive or negative effects. One positive effect is that the increased nutrient availability can lead to increased primary production. On the other hand, coastal hypoxia can increase or become more frequent, which has already been witnessed in previous OIF experiments. Cullen and Boyd (2008) further suggest, that all changes go on gradually, increasing with repeated fertilisation processes. However, the expected changes can so far not be quantified and we still rely on estimated values. Further research is still needed, before OIF can be seen as a promising and secure geoengineering method. The problem with predictions is the time scale, as experiments today can not show us the impact if iron fertilisation in 100 years. Furthermore there are likely to be other unpredictable effects, which result from the modification of the ocean system. The articles stresses the point, that currently uncertainties are still too high to make sell carbon offset, as it was also suggested. However, Cullen and Boyd (2008) see OIF as a promising method, which on the other hand bears risks.

I think they have a point. From what I have read, ocean fertilisation sounds as a promising option at first sight. However, in my opinion the uncertainties about side effects and long-term ecological consequences are still too high to modify the ocean system on such a large scale. It may be frustrating to repeat this with almost every suggested technique, but again further research is necessary to make a decision about the use of OIF.

Literature:

Cullen, J.J., Boyd, P.W. (2008) ‘Predicting and verifying the intended and unintended consequences of large-scale ocean iron fertilization’ Marine Ecology Progress Series, 364, 259-301.

Available online: http://www.int-res.com/abstracts/meps/v364/p295-301/

How to protect the planet

A little off-topic maybe, but here is a little cartoon about 'the perfect way to protect our planet'...

source: (http://www.haroldsplanet.com/daily/images/80_protect_planet.gif)

Should that make us think...?

Need for further research

"Geoengineering techniques need more study, says science coalition"

"The Solar Radiation Management Governance Initiative says geoengineering could be 'plan B' for climate change"

The guardian published an article about geoengineering on thurday this week. It states that geoengineering is not science fiction and could indeed be a way to combat climate change in future. However, it is still a 'risky business' and there is need for further research. In addition working together internationally and reducing political borders is essential for successful geoengineering.

Read the full article here:

http://www.guardian.co.uk/environment/2011/dec/01/geoengineering-techniques-study-science-coalition?newsfeed=true

Addicted to fossil fuels

(source: http://www.loleegreen.com/wp-content/uploads/2009/06/live-and-learn-or-vice-versa.gif)

Stratospheric Sulfur Injections

Today’s post focuses on an article by Crutzen (2006) with the title ‘Albedo enhancement by stratospheric sulfur injections: a contribution to solve a policy dilema?’. Crutzen describes the very controversial technique of actificially adding sulfur particles to the stratosphere to increase albedo.

Human emissions do not only consist of CO₂. Our industries also emit SO₂. Once emitted in the atmosphere SO₂ is processed into sulfate particles, which act as cloud condensation nuclei. More clouds can be formed, which causes a backscattering of incoming solar radiation and thereby enhances albedo. This can in consequence cool the earth’s surface and slow down global warming. The effect of great amounts of sulfur could be wittnessed after great volcanic eruptions e.g. Mount Pinatubo in 1991. The following diagram shows the reduced solar radiation that is transmitted after great volcanic eruptions:

(source: http://en.wikipedia.org/wiki/Stratospheric_sulfur_aerosols)

The idea of this geoengineering technique is now to artificially inject SO₂, S₂ or H₂S ‘near the tropical upward branch of the stratospheric circulation system’ (Crutzen 2006). This way the particles are transported into the stratosphere where they remain for 1-2 years. In lower heights in the troposphere their residence time is shorter and therefore more sulfur would be needed to achieve the same effect. So far this technique sounds like a solid plan, but it is not as easy as it seems to be: Sulfur can cause serious damage to the environment and to human’s health. It can e.g. cause premature death, “more than 500,000 […] per year worldwide (Crutzen 2006).

The dilemma is now that what is good for our health has negative effects in terms of climate change. A cleaner air can indeed lead to an additional warming of the earth’s surface. Crutzen estimates that a complete clean air leads to 0.8K warming of surface air temperature. However one suggestion is to clean the lower atmosphere level, which directly influence human’s health, and to inject sulfur above in the statosphere. Crutzen calculates the cost of stratospheric sulfur injections that are required to compensate for the additional warming and estimates a total price of US $25–50 billion/yr.

But is this really an option? As good as the intended effect is, we have to consider the negative side effects. In my opinion it is no solution to put at risk human health in this way. Sulfur particles may be injected in to the stratosphere but they will eventually loose height and affect us. I think the general idea to reflect sunlight is good, but there have to be other ways. Another method proposed is e.g. using mirrors in space or in the atmosphere. I want to discuss if this method might be an alternative in a later post.

What do you think about stratospheric sulfur injections? A way to save our climate or a way to destroy health and environment?

Literature:

Crutzen (2006) ‘Albedo enhancement by stratospheric sulfur injections: A contribution to resolve a policy dilemma?’ Climatic Change, 77 (3-4), 211-219.

Available online: http://www.springerlink.com/content/t1vn75m458373h63/ 

The Anthropocene

Today I want to present two articles by Steffen et al. (2007 and 2011), which give some background information on my topic geoengineering. They both deal with the Anthropocene, a term introduced about 10 years ago, describing the new era in Earth history which is strongly influenced by humans. The term is still not officially defined, but it generally describes the time until now where human influences on the Earth system became so strong and global in scale that they are able to modify the ‘great forces of Nature’ (Steffen et al. 2011: 843). The exact starting point of this time described as a new geological epoch is still discussed. Some scientists are of the opinion that clearing of forests 8000 years BP and first agriculture 5000 years BP are the first measurable human influences on e.g. the global carbon cycle. Human influence is also often linked to the extinctions of the Pleistocene megafauna. (Steffen et al. 2011)

However most scientist hold the opinion that the most determining factor for global changes in natural cycles is the industrialisation and the developments that followed. Whichever opinion is right, there are clear evidences for a strong human influence since the start of the Industrial Revolution 1700. The rise in atmospheric CO₂ is often taken as an indicator for human influence, as it is a result of fossil fuel use and other human activities e.g. deforestation  (Steffen et al. 2007 and 2011).

Due to the ability of natural carbon sinks to delay the response in CO₂ concentration in the atmosphere, the value for 1850 (285 ppm) is still within the natural variability of the Holocene. The human influence became visible later on: CO₂ concentration rose to 311 ppm in 1950, which is clearly beyond natural fluctuation (Steffen et al. 2007).

The time after 1950 is also described as the second stage of the Anthropocene or the Great Acceleration. The reason for this are the dramatic increases in the observed human impacts. ‘Every indicator of human activity underwent a sharp increase in rate around 1950’ (Steffen et al. 2011: 849). Changes can be seen e.g. in population, urban population, water use, transport or tourism:

source: Steffen et al. 2011, figure 1, p. 842

The same trends can be observed in natural cycles or events e.g. CO₂, N₂O and CH₄ concentrations in the atmosphere, flooding events or species extinctions:

source: Steffen et al. (2011), figure 1, p. 852

With those findings the human influence cannot be denied. The atmospheric CO₂ concentration reached 379 ppm in 2005 (Steffen et al. 2011), which is 102 ppm higher than the pre-industrial value of 1700. That means geoengineering techniques that aim so sequester CO₂ would have to deal with this amount of carbon dioxide, if we want to return to pre-industrial levels. 

The newer article from 2011 also highlights some points concerning geoengineering. It holds a rather critical view and reminds the reader, that side effects also have to be kept in mind. Steffen et al. (2011) chose the example of artificially added aerosols to illustrate the topic of geoengineering, but I don’t want to go into depth this time, as this is another technique that I want to present later in my blog. All in all the authors stress that further research is still needed before a decision on geoengineering can be made. In addition there are ethical, social and organisational/governmental questions that still need to be answered (Steffen et al. 2011).

Literature:

Steffen, W., Crutzen, P. and McNeill, J. (2007) ‘The Anthropocene: Are Humans Now Overwhelming the Great Forces of Nature?’, AMBIO, 36 (8), 614 – 621.
available online: http://www.bioone.org/doi/abs/10.1579/0044-7447(2007)36%5B614:TAAHNO%5D2.0.CO;2

Steffen, W., Grinevald, J., Crutzen, P. and McNeill, J. (2011) ‘The Anthropocene: conceptual and historical perspectives’, Philosophical Transactions of The Royal Society, 369, 842-867.
available online: http://rsta.royalsocietypublishing.org/content/369/1938/842.short

Public supports geoengineering. Really??

This comic that I found online ties in with my last posts and the idea of planting trees to offset some of the impacts of climate change:

source: http://www.cartoonmovement.com/cartoon/3058

It holds a rather critical view towards geo-engineering. But is that the overall public opinion? A recently published survey by A M Mercer, D W Keith and J D Sharp (available online) in Environmental Research Letters investigated the public understanding and opinion on geo-engineering, in this case especially on solar radiation management. When reading the results of their survey the first thing that stands out is that, as it seems to me, only a minority of people are familiar with geoengineering methods. While 20% stated that they have heard about geo-engineering before, only ‘8% of the population can correctly describe geoengineering’ (Mercer et al. 2011). According to the survey more people are familiar with the term climate engineering (45% were able to define it). When first asked if geoengineering should be a solution to global warming, respondents could give answers on a four-point scale (‘1 = strongly disagree and 4 = strongly agree’, Mercer et al. 2011). The mean answer was 2.35, which is relatively undecided with tendency towards disagreement. However a quarter of respondents selected unsure, which I think confirms that there is probably a lack of information in general public. While several newspapers or news websites like the Guardian or BBC report about this survey, I think that headlines should be treated with care: According to the survey ‘72% somewhat or strongly support’ (Mercer et al. 2011) allowing research on solar radiation management. In the press and in many headlines or blogs online on the other hand it appears that 72% generally support geoengineering. This again could give a false idea about what is actually said in the study.  There are already some strong reactions e.g. this video I found on youtube. It refers to the BBC article from last week.

http://www.youtube.com/watch?v=PfIpEl-WKrM

I think it is very important to pronounce statements like this carefully to prevent misunderstanding. It is important to inform the public about what geoengineering methods are and what effects they aim at. As the survey also shows that scientists are considered trustworthier than governments, the source of information could also influence respondents. 64% of respondents supported the statement that ‘humans should not be manipulating nature’ (Mercer et al. 2011) and 2/3 doubt that one technology alone is sufficient to fix the earth’ complicated climate. From my point of view the survey shows that there is still a lack of information in general public, but that the majority of people would support further research – this does not necessarily imply the implementation of geoengineering methods.

So what do you think about geoengineering in general? Is it a solution to our problems? And is it even possible to come to a definite conclusion?

Literature:

A M Mercer, D W Keith and J D Sharp (2011) 'Public understanding of solar radiation management', Environ. Res. Lett., 6 

Discovery Project Earth

The following video shows a brief summary of Dr. Mark Hodges' idea of planting trees on a grand scale via aircrafts.


Source: http://dsc.discovery.com/videos/discovery-project-earth-raining-forests-in-a-nutshell.html

Planting trees?

Another way that was proposed to mitigate climate change is to 'simply' plant more trees. Carbon dioxide circulates between different reservoirs. Forests currently cover roughly 1/3 of the world’s land surface and are the most significant terrestrial carbon store (Eliasch 2008). Trees sequester CO₂ through photosynthesis and store it in their biomass. This is the reason why one geo-engineering approach suggest to plant more trees to compensate for anthropogenic CO₂ emissions. But can that really work?

When examining this approach it falls into place that CO₂ reduction is not the only impact of planting new forests. Other biophysical effects like changes in evapotranspiration, cloud formation and albedo also have to be taken into account (Bala et al. 2007, Betts 2000, Gibbard et al. 2005).

Albedo effects are especially significant in boreal forest regions. Planting trees leads to a decrease in albedo most notably in winter, because bare ground, lower vegetation structures and snow-covered ground have a higher albedo than forests. Afforestation therefore has a warming effect at high latitudes and is therefore counterproductive,  because the albedo effect outweighs the cooling effect though carbon sequestration (Bala et al. 2007, Betts 2000, Gibbard et al. 2005).

Tropical forests at low latitudes in contrast have higher rates of evapotranspiration and for this reason more clouds are formed. In addition to the carbon induced cooling effect, evapotranspiration leads to a cooling and cloud formation enhances albedo. Thus the net effect of afforestation at low latitudes is cooling (Bala et al. 2007, Betts 2000, Gibbard et al. 2005).

Temperate forests take an almost neutral position in this geo-engineering method. According to Bala et al. (2007) warming effects due to a albedo descrease and cooling effects carbon sequestration even out.

The following graphic taken from Bonan (2008) illustrates the environmental impacts of the three mentioned forest types (A-C) and their geographical distribution:

There is still a need for further research on the quantity of effects and on comparison of different models, but so far the conclusion can be drawn that forestation CAN have a positive impact on mitigating climate change, IF applied in the right place. Afforestation on a large scale at low latitudes can have a cooling effect, while it would only increase warming at higher latitudes.

Literature:

• Bala, G., K. Caldeira, M. Wickett, T. J. Phillips, D. Lobell, C. Delire, and A. Mirin (2007): Combined climate and carbon cycle effects of global deforestation, Proceedings of the National Academy of Sciences, 104(16), 6550-6555. Available online: http://caos.iisc.ernet.in/faculty/gbala/pdf_files/Bala_etal_PNAS2007.pdf

• Betts R.A. (2000): Offset of the potential carbon sink from boreal forestation by decreases in surface albedo, Nature, 408, 6809, 187-190 Available online: http://www.nature.com/nature/journal/v408/n6809/full/408187a0.html

• BonanBetts, G.B. (2008): ‘Forests and Climate Change: Forcings, Feedbacks, and the Climate Benefits of Forests’, Science, 320, 1444 - 1449. Available online: http://www.sciencemag.org/content/320/5882/1444.full

• Eliasch, J. (2008): Climate Change: financing global forests: the Eliasch review, London: Earthscan. Online version: http://www.official-documents.gov.uk/document/other/9780108507632/9780108507632.pdf

• Gibbard, S. et al. (2005): Climate effects of global land cover change, Geophysical Research Letters, 32, 23. Available online: http://www.agu.org/pubs/crossref/2005/2005GL024550.shtml

Impact of cloud seeding on hydrological cycle

Today I want to briefly amend another aspect to the method introduced in my last post. The study by Bala et al. (2010) deals with impacts of cloud-seeding on the hydrological cycle. The method of cloud-seeding produces low-level clouds only above the ocean while the cloud layer above land remains unmodified. That means solar radiation is only reduced over the oceans. Nevertheless this geo-engineering method has an impact in the whole hydrological system. The article further describes that reflecting radiation via maritime clouds leads to a decrease in global mean precipitation and evaporation (1.3%) but an increase in runoff over land (7.5%) and land-mean precipitation. According to the study this is a result of the cooling of the atmosphere over the oceans which leads to a ‘monsoonal circulation with rising motion over land (...), and sinking motion over ocean with associated statistically significant increases in precipitation over land.’ (Bala et al. (2010): 927)

The study emphasises that an enhancement of albedo does not only have a cooling effect for our climate, but that that there are other side effects that have to be kept in mind. It is mentioned that those results contrast with previous studies, which is why further research is necessary before a decision on the implementation of cloud-seeding on a global scale is made.

Literature:

Bala, G., Caldreia, K., Nemani, R., Cao, L., Ban-Weiss, G., and Shin, H.-J.: Albedo enhancement of marine cloud to counteract global warming: impacts on the hydrological cycle, Clim. Dy- nam., doi:10.1007/s00382-010-0868-1, 2010.

available online: http://www.springerlink.com/content/9569172415150486/

Seeding maritime clouds to enhance albedo?

The first method I want to focus on tries to increase the earth’s albedo to prevent a further rise in global temperature as presented in Latham et. al (2008). In order to achieve this goal scientists try to seed low-level maritime stratocumulus clouds.

Clouds can contribute to the cooling of the earth’s temperature through albedo, but can also have a warming effect by reflecting long-wave radiation from the surface into space. The method of seeding clouds seeks to increase the albedo and thus the cooling effect of the cloud layer by increasing the natural droplet number concentrations. (Latham et al. 2008). This methods works as follows:

• Seawater droplets from the ocean surface are disseminated into the air to form cloud condensation nuclei (CCN). CCNs are solid particles in the atmosphere that are needed for water to coalesce droplets. In this case salt, that remains after the disseminated water particles evaporate, acts as the solid particle.
• Thus additional droplets can be formed and the enhanced total droplet surface of a cloud leads to an increase in albedo.
• As an additional effect it is possible that clouds are more stable and persist longer.
• The technical implementation of cloud-seeding requires ships for the dissemination of seawater. Scientists suggest to use ships with special ‘Flettner rotors’ which allow unmanned and remote-controlled vessels. These rotors are ‘vertical spinning cylinders that use the Magnus effect to produce forces perpendicular to the wind direction’ (Salter et al. (2008)).

 (source: Salter et al. (2008): 3998, figure 8)

Latham et al. suggest that ’doubling of the natural droplet concentration (...) would produce cooling sufficient roughly to balance the warming associated with CO₂ doubling.’ (Latham et al. (2008): 3971)

According to the essay of Latham et al. the method is not yet fully developed and ready to be applied at a global scale, but the authors are positive that cloud-seeding could stabilise the average global temperature, once all open questions are answered.

To get a better insight in how the implementation of such an idea could look like I recommend watching the following BBC report. It summarises the idea of cloud-seeding and shows the technical implementation:

So could this method really stop global warming? On the first sight it sounds like a ‘mild’ form of geo-engineering as no chemicals or big machinery is used and the dissemination of seawater can be stopped relatively quick. But on the other hand there may be other side effects caused by a higher salt concentration in the air. This could have an influence on ecosystems and soils if transported towards the land. I think these side effects need to be considered but if they are not significant and cloud-seeding really has good results in enhancing albedo it may be a good way to at least slow down global warming.
What do you think? Should we use this method in future times?

Literature:

• Latham, J., Rasch, P., Chen, C.-C. J., Kettles, L., Gadian, A., Gettelman, A., Morrison, H., Bower, K. & Choularton, T. (2008): Global temperature stabilization via controlled albedo enhancement of low-level maritime clouds. Phil. Trans. R. Soc. A 366, 3969–3987. Available online: http://rsta.royalsocietypublishing.org/content/366/1882/3969.abstract?sid=43023fa5-b6bb-436b-9101-8ab82698ff60

• Salter, S., Sortino, G. & Latham, J. (2008): Sea-going hardware for the cloud albedo method of reversing global warming. Phil. Trans. R. Soc. A 366, 3989–4006. Available online: http://rsta.royalsocietypublishing.org/content/366/1882/3989

What is geoengineering?

Before focusing on a particular method I first want to give a brief overview over geoengineering. It is a frequently-used and yet very vague term. But what exactly does geoengineering mean? What methods are described as geoengineering? Although there is no standardised definition for the term one can find many attempts to define it. David W. Keith gives a short and nicely illustated overview over what is implied in the term ‘geoengineering’: ‘Geoengineering is planetary-scale environmental engineering, particularly engineering aimed at counteracting the undesired side effects of other human activities’ (Keith 2001: 420). This comprises all actions that intent to have an effect on environmental conditions and that operate at a large (i.e. global) scale. In most cases specific sophisticated technology plays an important role in realising a geoengineering method. However the distinction between geoengineering methods and other methods that do not meet both of the two mentioned conditions is not always clear.

The term geoengineering was first used in the early 1970s, as scientists realised that using fossil fuels has an impact on our environment and climate. They tried to inject CO₂ into the deep ocean. The term became then more popular in the 1990s in discussions about climate change. (Keith 2000: 248)

Geoengineering focuses on different aspects that could help to slow or stop global warming e.g. reducing the solar radiation by using giant mirrors in space, fine particles in the atmosphere or artificial clouds. Other methods focus on decreasing the amount of CO₂ in the atmosphere by enhancing oceans sinks through fertilization with iron, terrestial sinks or biological sinks e.g. forests.

There are various ways in which scientists try to find a solution to global environmental change. Which methods are feasible and can actually be successful remains to be seen.

Literature:


      D. W. Keith (2001). Geoengineering. Nature, 409: 420.

PDF available online:

http://people.ucalgary.ca/~keith/papers/37.Keith.2001.Geoengineering.e.pdf


David W. Keith (2001). Geoengineering and carbon management: Is there a meaningful distinction? Greenhouse Gas Control Technologies: Proceedings of the 5th International Conference. D. Williams, B. Durie, P. McMullan, C. Paulson and A. Smith eds., CSIRO Publishing, Collingwood, Australia, p. 1192-1197.

PDF available online:

http://people.ucalgary.ca/~keith/papers/41.Keith.2001.GeogineeeringAndCarbonManagment.f.pdf

Plan B for Climate Change?

This blog is part of the course ’Global Environmental Change’ at University College London. I chose the title for my blog ‘Plan B for climate change’ because finding ways to combat global warming and man-made climate change is one of the biggest challenges we have for the future. In this context geoengineering has become a very popular term and various ways of changing the current trends are discussed among experts and even in general public. Therefore I will have a closer look at different geoengineering techniques, their function and feasibility as well as benefits and/or disadvantages to see if geoengineering could really be a plan b for our environment.