Geoengineering broadly means manipulating the natural climate of the Earth on a worldwide scale. It is also called climate intervention or climate engineering.
Currently, our planet is approaching warming of nearly 2C. The IPCC (International Panel on Climate Change) has made staying below 2C humankind’s most urgent goal. However, the temperature threshold is expected to be broken soon if current rates of emission are maintained. This has pushed scientists and policymakers to give serious consideration to geoengineering.
However, technologies for geoengineering are not yet large enough to impact the whole planet’s climate. Nevertheless, their potential ability to combat, or reverse, climate changes is gaining more and more attention.
Primarily, two geoengineering types exist: solar and carbon dioxide. Solar geoengineering involves manipulating the Sun’s radiation that reached the Earth. CO2 geoengineering involves the removal of CO2 from our atmosphere.
This is also known as radiative forcing geoengineering. It aims to cool our planet by altering how much of the Sun’s radiation is collected by the Earth. The rate of radiation received by the Earth is relatively consistent. Solar radiation has nothing to do with our current climate change. However, global temperatures can be reduced by reducing how much of the Sun’s radiation reaches the planet. This, in turn, would drastically impact climate change.
However, this method will have no impact on the greenhouse gas amount in the atmosphere. As such, effects of climate change that have no relation with global temperatures, such as ocean acidification, will not be affected.
This method will involve reducing the atmospheric CO2 by manipulating the planet. Compared to solar geoengineering, CO2 geoengineering will focus on the root cause of climate change, the increasing greenhouse gases, directly.
Generally, techniques of CO2 geoengineering make use of biological processes found in nature to absorb and store CO2 from the air. CO2 geoengineering will make such natural processes faster to increase the rate of removal of atmospheric CO2.
How Is Geoengineering Done Exactly?
For solar geoengineering, scientists talk about building mirrors in space to manipulate the radiation reaching the Earth. Other methods include injecting the atmosphere of the planet with special materials or increasing the rate of reflection of the land.
The main methods involved in CO2 geoengineering so far are increasing the surface area of forests on Earth, using Iron to fertilize the oceans, and making use of techniques to reflect radiation.
This idea was first suggested by Walter Seifritz in 1989. Then James Early gave an elaboration three months after the first publication. More recently, in 2006, a study had proposed installing small sunshades, making a “cloud”. Roger Angel, the author, gave an estimated cost of several trillion dollars.
Radiation Reflection Using The Atmosphere
Another method suggested is making the planet’s atmosphere more reflective. This can be done by suspending aerosols, or fine particles, which will reflect radiation into space. Scientists can enhance the natural process by intentionally adding more aerosols.
Land-Based Reflection Of Solar Radiation
There have been several suggestions as to how to increase the reflectivity of the land. Ideas, so far proposed, include building roofs from reflective materials, introducing subtropical countries to reflectors, or modifying flora genetically to produce species that have lighter colors.
This has been the topic of most discussions regarding CO2 geoengineering. It will make use of the algae in the ocean to produce sugars and oxygen from atmospheric CO2. However, a natural deficiency of iron keeps them from existing in high numbers in oceans. So adding iron can result in a huge algae bloom. These will be just as big as the natural algal blooms, but not destructive to the ecosystem like them. Moreover, once the iron runs out, the dead algae sink to the floor of the ocean, where the CO2 remains stored.
Perhaps the oldest and most easily accessible form of geoengineering is increasing forests. A further step has been suggested in which dead trees will be buried deep underground. There, instead of releasing the CO2 due to the usual process of decay, a new tree will replace them. Biochar, or a type of charcoal rich in carbon when vegetation is burned without oxygen, can also store carbon when buried.
Geochemical weathering is the process by which carbon builds up in rocks through rainwater over time. Scientists have proposed manually injecting CO2 into aquifers of basalt, thus making the process quicker. When stored in minerals, the carbon in CO2 becomes a stable compound that cannot easily turn back into a greenhouse gas.
The Positives And Negatives Of Geoengineering
Solar engineering, by itself, can reduce global temperatures back to how it was before the industrial revolution. This would have a direct impact on many areas such as the ice sheets that are melting or the coral reefs. CO2 thermal geoengineering can be even more rewarding since it will be tackling the primary cause behind climate change.
However, when these technologies are used on a planet-wide scale, there are expected to be serious consequences. For example, solar radiation reflection will reduce the amount of rainfall worldwide. On the other hand, algal blooms that are artificially induced can misbalance the natural structure of the different species of algae. It can result in proliferating algae that produce toxins. Moreover, so far, any attempts of ocean fertilization have been unsuccessful.
However, the biggest challenge facing geoengineering is undoubtedly its scale. To be properly effective, all nations and countries must agree to the projects, since it involves resources like the ocean and the Sun.