I have found there is no single answer for fixing climate via geoengineering. With all schemes I've studied there are disadvantages; whether it be cost, moral or environmental implications, social reasons etc. As a result I think it would be better to implement several techniques simultaneously (cost dependent of course), and a balance of SRM and CDR will be required to cool the planet more quickly as SRM doesn't deal with the amount of greenhouse gas currently in the atmosphere.
Although I've not posted about it directly I have found geoengineering is a 'moral hazard'. Conflict of interests occur about the idea as a whole, with massive organisations such as Oxfam and Greenpeace opposing the idea, suggesting it should only be used as a last resort. Most of the techniques I have looked at also have criticisms from the public and scientists alike; for various reasons. Sometimes these pressures can delay or even halt the implementation of a technique which could potentially rescue the planet; as I saw in the case of the UK testing of stratospheric sulfate aerosols for example. I've said it several times before but its great we can do such a thing as geoengineering and we should utilise it for our benefit.
SRM
The solar radiation management techniques I looked at were stratospheric sulfate aerosols, cool roofs, reflective desert crops, desert reflectors and space mirrors. Of all of these, I have found the space sunshade idea to be the least practical, mostly due to cost. Cost of research, production, launch and maintainance exceeds $1 trillion, basically meaning this idea is unaffordable (Koysugi 2010). Additionally, the majority of papers on the subject mention the need for further research, mentioning at least a decade until we would know for sure the effectiveness of the project; and I don't think we can afford the much time, as greenhouse gas emissions are rising dramatically each year.
My personal favourite SRM technique was injecting sulfate aerosols into the stratosphere to scatter incoming sunlight away from the Earth. I like how the idea has come from nature; volcanoes cool the planet upon eruption, as seen the Mount Pinatubo. The idea comes from Crutzen, who won a nobel prize for his work in 1995. The technology required is developed; meaning less funding required for research and the technique is proven to be highly effective. As sulfide injections are also a natural phenomena; it has allowed for indepth models and predictions to be made, as well as accurate evaluations of the costs and disadvantages.
Compared to some other techniques, this is relatively affordable and it has the advantage of guaranteed success is achieving a cooling effect, as well as an instantaneous effect. Lastly, there are minimal associated negative consequences of implementing the technique - a paper by Kravitz concluded there would be no negative consequences for ocean ecosystems, whilst Wu (2002) confirmed this was also the case on land. That is why if I were in charge of the world, I'd inject some sulfates into the stratosphere right away!
Lastly; surface albedo enhancement which can be broken down into several smaller schemes such as cool roofs, GM crops to enhance reflectivity and desert reflectors. Cool roofs is a great idea because it's so easy; paint your roof white and you'll have yourself money in air conditioning whilst saving the planet. Although obviously only beneficial in hotter climates, I think it's really important idea because it can be achieved on a local scale, and the public need to be aware of climate change and how easily they can make a difference. Although relatively cheap it would help if governments or organisations offered subsidies to cover the cost and hopefully encourage more buildings to adopt the technique.
Reflective crops are feasible and technologically ready, but it just doesn't produce a big enough effect to combat climate change solely. I think it could be helpful if implemented in conjunction with other geoengineering methods. Desert reflectors in my opinion are a cheaper, uglier version of space mirrors. Although they will do the job it has been predicted they will completely change precipitation patterns in vulnerable parts of the world, and they are very expensive.
ssa = lots of pressure from opposition,
CDR
I've seen carbon dioxide removal techniques in the form of ocean iron fertilization, afforestation, carbon capture and storage and the creation of terra preta. Ocean iron fertilization seems to be the least effective method, with only a handful of studies done on a largeish scale with underwhelming results. The effect is too short-term as the iron will become mixed in, and the cost too great to maintain continuous injections. Larger-scale experiments are required to answer the many questions which still need answering about using this technique, especially as it is very difficult to quantify the amount of carbon b eing captured and sequestered, making it hard to evaluate it's effectiveness. The technology implemented to achieve a result from iron fertilisation hasn't really advanced much in 20 years; and I think there are much better ways to fix climate change than stimulating algal growth.
Terra preta creation is an ancient idea stemming from the pre-Columbian Amazonian people. Palaeo records don't shed much light on whether they were formed intentionally or not, but it is clear they are huge soil carbon reservoirs. Their formation is limited due to social and economic reasons - farmers would have to give up their land in order to form it, and although they would probably benefit due to increased productivity, these effects wouldn't be felt for several years.
Afforestation is the most environmentally friendly technique; whereas practically all others produced some sort of negative environmental consequence, growing trees is the greenest thing you can do. However, this is not enough to halt and reverse the effects of global warming, and unfeasible to cover such a large area of landsurface with trees. Unfortunately as with terra preta, land inevitably belongs to somebody and if it is not economically viable for them to do this then it probably will not be applied. There are some success stories of countries offsetting their total emissions (such as Iceland) by afforestation, but the world's worst emitters (eg. China) aren't doing enough to offset, due to investing in the wrong type of tree. I think overall afforestation is a great technique but isn't big enough; although carbon is sequestered in the tree, roots and soil profile it would definitely need to be implemented correctly and coupled with another geoengineering scheme to be effective.
Lastly, carbon capture and storage. Definitely my favourite CDR technique; carbon can be removed during combustion or from ambient air and deposited deep underground, under the sea or in minerals and never seen again. This is the newest technique and has only been developed in recent years but has been adopted in various places all round the world; showing that it is worth investing in and has huge potential for tackling climate change. The fact this is such a new technology is a downfall as many schemes are only in pilot phases; but once further research has been applied I have a good feeling about this one and think it has huge potential to cool the planet. However, it's still unknown if it will be able to reverse the effects of climate change and even when the technology is readily available, if it will be to late to do so.
So overall? I think it would be better to focus most attention on a CDR technique(s), favourably CSS with the possibility so a SRM technique, preferably stratospheric sulfate aerosols. Perhaps aerosols could be injected to cool the planet while CSS is developed, and it could then take over as the main climate change mitigation technique. It is also essential to remember it is phenomenlly important to actively reduce our carbon footprint simultaneously with developing geoengineering methods. Although I have only touched on it, there are loads of small things (or even larger, like cool roofs) which are applicable on a local scale, and together all contribute to fixing climate change. Although science is a great thing, it should not be taken for granted; the 2 approaches need to be integrated and it is of paramount importance we reduce our emissions. I hope you have enjoyed reading about the geoengineering ideas as much as I have!
