What do the 1991 Mount Pinatubo eruption and an ocean filled with millions of white golf balls have in common? They can both combat climate change-potentially. Geoengineering was once seen as a ludicrous practice with no real utility outside of science-fiction. Today, however, climate scientists are conducting small-scale experiments and producing computer models to investigate the feasibility of tackling climate change by manipulating the weather. We have seen it happen in many other disciplines whereby scientists intervene with the course of nature. In biology, the genetic makeup of an organism can be altered using genetic engineering, likewise, geoengineering involves intervening with the Earth’s climate system.
A Brief History of Weather Manipulation
The Theory of Storms
The emerging point of weather manipulation is believed to be James Pollard Espy’s book ‘The Theory of Storms’. Published in 1841, this book outlined how if five conditions of rain cloud formation were met and we were to set ablaze ‘great fires’, we could artificially induce rain in times of drought.
Operation Popeye (1967-1972)
During the Vietnam War, the United States Air Force carried out a cloud-seeding operation intending to disrupt the North Vietnamese troops. During this operation, 2,600 planes flew over Laos, Cambodia and North and South Vietnam, and dispersed silver iodide and lead iodide into the clouds. This relatively simple operation extended their monsoon period by an average of 30 to 45 days and caused road surfaces to soften, outbursts of landslides and over-saturation of their crops. What is the science behind this?
General Cloud and Precipitation Formation
- When water evaporates and rises up in the atmosphere, at a certain level the ‘point of saturation’ will be reached. Here no more water vapour can be held in the air.
- When the water vapour comes into contact with a cloud condensation nuclei (CCN) such as floating dust, smoke and sea salt, it will condense into water droplets. The accumulation of these droplets will form clouds.
- Water droplets may increase in number and size by colliding and coalescing with each other. When the droplets possess a fall velocity greater than the cloud updraft velocity this will lead to precipitation.
Mechanism of Cloud Seeding
Static seed clouding involves the dispersal of silver iodide into clouds. The silver iodide particles act as a CCN, condensing water vapour into water droplets allowing the greater accumulation of droplets leading to greater precipitation.
Budyko’s Blanket (1974)
In 1974, Russian climatologist and one of the founding fathers of physical climatology, Mikhail Budyko, published a book called ‘Climatic Changes’. Here he outlined what is currently known as artificial solar radiation management. He predicted that to counterbalance the warming that occurred between 1920 and 1940, we must inject 200,000 tons of sulphur into the stratosphere. These are classified as Stratospheric aerosols and their purpose is to reflect some sunlight before reaching the Earth’s surface.
“These measures of climate modification are intended for preventing or weakening climatic changes that may ensue in several decades as a result of man’s economic activity. Such modification, however, is not beyond the capacity of modern technology.”Climatic Changes, M. I. Budyko
The SPICE Project (2010)
The Stratospheric Particle Injection for Climate Engineering (SPICE) project was a research project that was funded by the UK government aimed at investigating the feasibility of solar radiation management. This project drew inspiration from natural volcanic eruptions and their cooling effects. One extreme example is the 1991 Eruption of Mount Pinatubo in the Philippines. This event emitted millions of tons of volcanic gas and ash into the stratosphere of which 15-20 million tons was sulphur dioxide. This gas reacted with water to form a layer of sulfuric acid droplets which spread around the entire globe. As a result, the world saw a global temperature decline for two years and the average global temperature decreased by around 0.5 degrees Celsius, a value that at first glance may seem insignificant but is actually an immense decline in temperature. This was because the aerosol particles reflect and scatter incoming sunlight.
This project consisted of three key research areas:
- Evaluation of Potential Particles: What is the model particle? What particle would augment solar radiation scattering and have minimal negative effects on the environment and human health?
- Delivery Systems: What is the most sustainable method of delivering the particles? How viable is it to eject the particles using a tethered-balloon pipe delivery system?
- Environmental Modelling: What locations would be most efficacious? What are the climatic and environmental impacts of this project when conducted in a large-scale setting?
The end goal was to launch the first large-scale geoengineering scheme. The proposed test was to launch a weather balloon allowing it to disperse 150 litres of water into the atmosphere. The balloon would be attached to a 1km pipe tethered to a ship. The hope was that the cooling effect achieved by volcanic eruptions would be mimicked, however, the ‘test bed’ was initially delayed by six months until it was terminated a year later in 2012. One of the reasons stated was the insufficient government ruling regarding large-scale geoengineering schemes.
It is with some regret that today the SPICE team has announced we’ve decided to call off the outdoor ‘1km testbed’ experiment that was scheduled for later this yearMatthew Watson in an email to Nature in 2012
The Modern Era of Geoengineering
As previously demonstrated, weather manipulation can serve as a military tactic, a way to increase crop livelihood during droughts or to combat anthropogenic environmental change. Geoengineering, as defined by the Oxford Geoengineering Program, is ‘the deliberate large-scale intervention in the Earth’s natural systems to counteract climate change.’ In other words, using weather manipulation for the sole purpose to counteract the effects of climate change. Geoengineering can be classified into two groups: solar radiation management (SRM) and greenhouse gas removal (GGR).
Solar Radiation Management (SRM)
SRM techniques involve reflecting sunlight back into space to counterbalance global warming. Here are some of the bizarre ideas proposed:
- Mining moon dust to manufacture sun shields
In a 2007 research paper, astronomy professor Curtis Struck of Iowa State University, proposed a space-based SRM. He outlined how if moon dust is injected at two specific locations along the Moon’s orbit, a pair of stable clouds would form and would act as a solar shade by deflecting sunlight.
- Cloud Whitening
This technique is used to increase the albedo (the portion of light reflected from a body) of stratocumulus clouds by injecting a mist of sea salt spray into the clouds. Acting as cloud condensation nuclei (CCN), the salt particles cause an increase in water vapour condensing into droplets thus increasing their number and they also reflect incoming sunlight. The overall effect is brighter clouds with a greater ability to reflect insolation.
James Early in 1989 suggested manufacturing a 2000 kilometre wide glass shield that would be placed into an inner Lagrange point. This shield would diffuse and prevent significant amounts of sunlight from reaching the Earth. In general, Lagrange points are sites in space where objects tend to stay still. However, due to the sunshade’s massive size, if this method was to be carried out we would have to colonize Mars, build the sunshade from there and launch it.
Greenhouse Gas Removal (GGR)
As the title indicates, these techniques involve removing greenhouse gases (typically carbon dioxide) from the atmosphere to offset the greenhouse effect.
- Carbon Capture & Storage (CCS)
The CSS chain consists of three parts: capturing, transporting and finally storing the carbon dioxide.
- Capture and transport of carbon dioxide
A chemical solvent -usually an amine solution- can be used to ‘capture’ carbon dioxide from traditional power plants’ exhaust gas. The amine solution binds with carbon dioxide and this product is separated from the exhaust gas. This is then heated to collect carbon dioxide ready for it to be transported and stored.
- Storage of carbon dioxide
Once the transportation process is complete, carbon dioxide is stored several miles underground in porous geologic structures where the temperature and pressure will allow the carbon dioxide to remain in the liquid phase. Ideal storage locations include former gas and oil fields and depleted oil and gas reservoirs. The carbon dioxide may find itself progressing through four types of storage.
- Capture and transport of carbon dioxide
Firstly, when carbon dioxide is injected into a geologic structure it will start to advance up the storage site until it is halted by a layer of impermeable rock (cap rock) this is named ‘structural storage’. Through its movement towards the caprock, some carbon dioxide will be trapped between the minuscule pores of the rock which is known as ‘residual storage’. If a saline solution is present in the geologic structure, the carbon dioxide will dissolve in it, increase its density and cause the solution to descend to the base of the storage site. This is known as ‘dissolution storage’. The final storage phase is called ‘mineral storage’ and occurs when the carbon dioxide binds permanently with the surrounding rock. As the carbon dioxide advances through each phase it becomes less mobile leading to a lower chance of leakages.
Examples of successful running CCS initiatives include Petra Nova (a multi-million dollar project) in the United States which utilizes post-combustion capture to capture 5,000 metric tons of carbon dioxide daily from one of the boilers of a Texas-based coal-burning power plant. The first commercial CCS facility in the iron and steel industry was co-created by The Abu Dhabi National Oil Company and Abu Dhabi Future Energy Company. This initiative boasts an annual capture of 800,000 tonnes of carbon dioxide a year.
- Ocean Fertilization
This process involves inserting nutrients such as iron or nitrates into specific areas in the upper layer of the ocean. This promotes phytoplankton growth and its photosynthetic activity to (in theory) increase the uptake of carbon dioxide. The ‘theorised success’ is based on the notion that when the phytoplankton dies, it will sink to the bottom of the ocean and the carbon would sequester.
Scientific research revealed that the uptake of carbon dioxide by phytoplankton is much less than what is anticipated and the amount of carbon that reaches the base of the ocean is very low due to the amount that is reintroduced by the food chain.
Challenges and Ethics
The vast majority of the proposed geoengineering projects are still either theory-based, have not been tested or have come back with unsuccessful results. However, many research groups are still active, and so is the widespread criticism.
A research paper titled ‘Stratospheric aerosol injection tactics and costs in the first 15 years of deployment’ concluded that solar radiation management techniques (in particular stratospheric aerosol injection) are relatively inexpensive and do not require advanced technology to operate. This means that any government can easily deploy these methods at the expense of another country. For example, one country could launch ‘space mirrors’, these would reflect sunlight away from the Earth and potentially combat global warming. However, climate models demonstrated that parts of Northern Eurasia and North and South America would receive 10-20% less rainfall if these space mirrors were launched. So the question is who will be in charge of the immense responsibility of geoengineering the planet? Who will decide which methods will be used?
Many climate scientists worry that world leaders will see geoengineering as an easy and cheap way out of climate negotiations and achieving the carbon emission targets. That is why geoengineers and advocates of these technologies continue to warn that geoengineering should be seen as a backup plan in case we are unable to reduce our fossil fuel consumption. Human modification to the Earth has had a vast array of unintended and unexpected impacts. For example, something as simple as constructing many buildings has led to a phenomenon called urban heat islands whereby urban areas are significantly warmer than their surrounding areas. The climate system is very complex and dynamic and tampering with this intricate structure could yield disastrous results-the majority of which are unknown.