CAJ - The negative side-effects of spraying stratospheric sulphate aerosols

The negative side-effects of spraying stratospheric sulphate aerosols

In order for you to get to know all aspects of this geoengineering technique and understand why it is such a heated topic, I like to present even the possible side-effects that may occur with the realization of it. Some scientists say that this strategy to counter global warming could reduce the amount of electricity which is produced through solar power. However, David Keith, one of the leading scientists around geoengineering, does not find this argument convincing and he believes that the creation of electricity through solar energy can only be  negatively affected when solar geoengineering is being used very heavily. Most of the arguments are based on an analysis of the volcanic eruption of Mt. Pinatubo. Injecting sulphate aerosols, as what happened after the eruption, may reduce the total amount of water vapor in the atmosphere. Another fact attributed to the eruption and therefore can be seen as a side-effect of this geoengineering technique is the possibility of rough, widespread droughts. David Keith said that he has not seen a serious, direct analysis that supports this argument. Furthermore, this technique could alter weather patterns such as precipitation and increase acid rain. 

 

Another potential consequence of this technique is the increase in ozone depletion. The ozone hole over Antarctica is caused by a chemical reaction and introducing sulphate aerosols could increase the surface area on which these chemical reactions occur. As a consequence, the ozone hole would become larger and more ultraviolet radiation could reach the Earth.
One critical issue remains: Solar geoengineering does not reduce the danger of CO2 emissions. People/Countries/Cities/Companies would continue to live their lifestyles the way they have, creating too much CO2 emissions and thereby worsening global warming. Moreover, the spraying of sulphate particles does not solve the problem of ocean acidification which harms coral reefs and many other marine lives. 

However, studies that have been carried out have proved that crop yields could potentially increase in some regions, because plants grow more efficiently in diffuse light. Another interesting fact is that CO2 from the atmosphere could actually have a fertilising effect on crops. Isn't that fascinating?

CAJ - Stratospheric Sulphate aerosols

Stratospheric sulphate aerosols

The last Geoengineering technique in the group of solar radiation management is the spraying of sulphate aerosols into the upper atmosphere, also called the stratosphere.

So far, the strategies to reduce greenhouse-gas emissions have not shown any effective results. The rate of emissions is actually even beyond the level which we thought is too dangerous a couple of years ago. The Intergovernmental Panel on Climate Change foresees a rise of 2.0 to 5.2 or 11.5 degrees in 2100. Scientists expect this rate to become even higher since developing nations such as India or China will burn more coal and use more vehicles. Even if we all stop creating carbon emissions immediately, which will obviously not happen, the problem of global warming would still persist. A great deal of the heat-trapping gas is expected to remain for decades, even for centuries, in the atmosphere. Doomsayers among scientists say that whatever we do with the existing carbon emissions, we will still face the threat of a worsening of global warming. To avoid the planetary warming getting even worse than it is now, scientist keep on saying how important it is to finally take effective revolutionary measures, a plan B so to speak. This is where the geoengineering technique of spraying sulphate aerosols becomes attractive. By implementing this technique, we could easily solve the problem in a short period of time. The best thing about this technique is that the costs would be minimal. To be precise, it would not cost more than military spendings which means a few billion dollars annually. With this in mind, would it not be more useful to invest this money in something important such as in measures to prevent global warming? Shouldn’t humanity have already reached the point where we can evaluate what really is crucial for the future of the planet? Why throw money out of the window? Shouldn’t we do anything to prevent long-term consequences of global warming such as rising sea levels, increasingly severe storms and droughts, melting glaciers as well as permafrost? In fact, the idea of countering global warming with airplanes in the stratosphere, burning sulphur to make aerosols, goes back to the mid-1970s. How and why did a shift in our thinking about global warming occurred?

Let’s get back to the technique itself:

Sulphate aerosols are considered an important part of the Earth system in the stratosphere as well as in the underlying troposphere. These particles have been studied for a long time since they play an essential role in the chemistry of the the lower stratosphere and, when it occurs, after a volcanic eruption. Sinks of aerosols are so much stronger in the troposphere and they only remain in the troposphere for a few days. However, stratospheric aerosol stay in their layer for approximately a year. The fact that their lifetime is longer means that only a few aerosols need to be introduced per unit of time to create an aerosol burden and to have them dispersed over a large area. This dispersion has a global, not a local, effect which is a very important aspect of geoengineering techniques. Sulfate aerosols occur naturally in the stratosphere because of the transport of natural sulphur compounds from the troposphere. Much higher concentrations are introduced when a volcanic eruption occurs, such as what happened with the Mt. Pinatubo. This eruption results in a temporary cooling of the Earth’s system. The eruption causes sulfur dioxide (SO2) to convert to sulfuric acid (H2SO4) that condenses rapidly in the stratosphere to form fine sulfate aerosols. Winds in the stratosphere spread the aerosols until they cover the globe. Once these aerosols are formed, they remain in the stratosphere for approximately two years. They reflect sunlight and thus reduce the amount of energy that reaches the lower atmosphere, the troposphere, and the Earth's surface. On the other hand, they also absorb heat which is radiated up from the Earth. 

The relative coolness of 1993 is thought to have been a response to the stratospheric aerosol layer that was produced by the Mt. Pinatubo eruption in 1991. The volcanic introduction of sulphate aerosols, therefore, serves as a natural simulation to the geoengineering technique. The only difference is that the volcanic aerosols remain in the stratosphere for a few years, whereas the injected particles will have to be introduced regularly to balance the global warming temperatures. 

Just to give you an idea of how many aircrafts you will see flying  in the future if it really comes to the implementation of this geoengineering technique: For a total aerosol mass injection of particles per year, one million flights  and several thousand aircrafts need to be active continuously in the future. 

How can these aerosols be delivered into the stratosphere?

The methods and ways for how to actually introduce sulphate aerosols into the stratosphere have been neglected in the current geoengineering proposals. There are many challenges when it comes to creating a delivery system that can inject the right amount of aerosols. Earlier papers have suggested some delivery system that inject sulphur using artillery shells, high flying jets or balloons. However, among the dangers that exist with these delivery systems is an unequal and inadequate distribution of the aerosols .This could result in the formation of larger particles which are known to rain out quickly and have shorter stratospheric lifetimes. However, factors like particle size, location as well as lifetime of aerosols need to be taken into account when inventing delivery systems.

CAJ - Arguments in favour of Geoengineering

To give you an insight into all the different opinions about Geoengineering, I would like to present some of the arguments in favour of Geoengineering. They should help to illustrate the necessity of Geoengineering, so here you go:

One strong argument in favour of Geoengineering says that it’s probably the only way to save summer sea ice in the arctic. Once ice goes away entirely, it will be very difficult, if not impossible, to get it back. Once summer ice melts to open water, the albedo, which is the fractionof solar radiation reflected back into space as I have mentioned it in my introduction before, would drop from 0.6 to 0.1. This could accelerate rapid warming in the Arctic.  In fact, some scientists believe summer sea ice may disappear in the arctic by 2015 since the minimum sea-ice volume is falling continuously. I strongly recommend typing "Summer sea ice level dropping" into Google and looking at the results. It's quite shocking to know that these predictions might become reality soon, only 50 years from now.

This is a graph taken out from a NOAA report

They also argue with the following facta: Approximately one third of emitted carbon dioxide is already absorbed by the oceans, which became more acidic as a result. Oceans are already 30% more acidic today than they were in preindustrial times. If current emissions continue, most coral reefs could be gone by the end of the century, along with them all the ecosystems they support. Another fact is that carbon dioxide levels throughout the northern hemisphere have risen in April to 400 parts per million for the first time in history.The WMO (World Meteorological Organization) actually expects the concentration to be above 400 parts per million in 2015/16.

Furthermore, most scientists believe that reducing emissions of greenhouse gases is the safest way to prevent global warming, but they claim that this not enough to stabilise global temperature and consequently reduce global warming. Even though it’s unknown what level of greenhouse gases in the atmosphere need to be reduced for a stable climate and a reduction of ocean acidification, scientists say that it is still important, if not essential, to minimise this level as much as we can. The fact itself that we do not know exactly how the climate system could react to growing greenhouse emissions is a reason to counter against it.  Therefore, Geoengineering would be the best way since it could solve the problem much quicker. It could forestall the consequences of emissions by protecting vulnerable natural ecosystems such as the arctic, or coral reefs, from damage.

Most scientists say that we should consider anything that could prevent global warming, including Geoengineering. Given our current situation where greenhouse gas concentrations in the atmosphere are continuously growing, we should not leave any prophylaxis out of  consideration.

Scientists highly encourage further research in this field too. They claim that not sufficient geoengineering research have been conducted. In fact, scientists are reluctant to do so because they fear that knowing how to engineer the climate would encourage people to do it for power purposes. Only proper studies show what can be changed to improve suggested Geoengineering techniques and how Geoengineering side effects, that may be detrimental to the ecosystems in the process, could be prevented. Only by having good research can we counterargue against Geoengineering.

They argue that if indeed climate-change predictions became suddenly reality and people became at risk, the population shouldn’t be ignorant about the ways to prevent it. Without proper research, nobody would know what can come out of a crash implementation of Geoengineering.

In addition to that, scientists who advocate in favour of Geoengineering keep saying that the costs of Geoengineering techniques are much cheaper than the costs of reducing carbon dioxide emissions in the atmosphere. Particularly SRM techniques, which basically aim to reflect sunlight back into space, are cheap and convenient. A few grams of sulphate particles cost about a dollar per kilogram and considering that it could balance the warming of a tonne of carbon dioxide, this technique seems to be quite effective. In fact ,the current global warming level could be reduced at least one hundred times cheaper than by emissions cuts. A recent analysis of Geoengineering costs by McCennan concluded that the climate could be balanced with exisiting technology at a cost of less than 8 billion dollars per year. 

All in all, scientist advocate in favour of Geoengineering by giving proper facts about the current global warming situation. This makes their arguments more credible compared to the arguments against Geoengineering.

CAJ - Opinions against Geoengineering

Opinions against Geoengineering

As Geoengineering is a large global scale project and involves significant changes to our environment, this issue has become somewhat controversial among scientists. Some of them claim that the intervention into the Earth’s climate system could have severe consequences. Instead of improving global warming, Geoengineering techniques would worsen the whole situation...well, so they claim.

In this post I will present you some of the arguments against Geoengineering. 

Most of the scientists are sceptical when it comes to spraying aerosols in the air to make the Earth more reflective. Dr. Charlton-Perez, a lecturer of Meteorology, fears that the particles would not only absorb the Sun’s heat but also the heat energy that comes from the Earth. He also fears that the stabilisation of the Earth’s climate could reduce the upwelling of air. This would seem like a big problem in the tropics since rain falls when the air moves rapidly. This climate stabilisation, as a result, would reduce precipitation in the tropics. As a matter of fact, rainfall around the tropics could be reduced to 30%. This would significantly impact rainforests in South America and Asia. It’s quite scary if we consider the fact that tropics play an essential role in the Earth’s climate as the trees capture high amounts of carbon.

He also claims that it would lead to an increasing drought in Africa.

He backs up his arguments with a study his team carried out to measure what negative effects Geoengineering techniques could have. The study considered what would happen if carbon dioxide levels quadrupled in the atmosphere. This extreme situation showed that without intervention, temperatures could rise by 4C, far above the 2C level considered dangerous. After that, they reduced the temperature rise to zero - the level it should be after Geoengineering measure will have been introduced.

In the simulation, they have pumped up a huge amount of sulphur dioxide into the stratosphere. The amount is equivalent to five volcanic eruptions of the Mount Pinatubo in 1991 which, as a result of its eruption, reduced global temperatures by 0,5C in the following years.

The sulphate particles in the model did not only reflect incoming sunlight, but also heat rising from the Earth’s surface. As a consequence, it reduced the temperature difference between the lower and upper atmosphere which is the engine that drives cloud formation and rainfall.

Scientists worry that an adaptation to this drastic change could threaten to the flora and fauna as well as people.

Interesting, isn’t it?

Another argument he states which is worth mentioning is that Geoengineering effects will not be the same everywhere. This leads to the future possibility of conflict between nations that might benefit from it and the ones which might suffer from it. He points out that governance over Geoengineering is another issue that speaks against climate intervention. This issue concerns Dr. Matthew Watson, a lecturer of the University of Bristol, too. He points out that strong, sensible and reasonable governance is crucial for this global-scale project, even on small-scale outdoor experiments.