What is Geoengineering?

By Ben PilkingtonSep 3 2012

To combat climate change, scientists are coming up with many weird and wonderful (and in some cases workable) methods of altering the atmosphere to suit our needs. Image Credit: NASA

Geoengineering is a broad term that covers various techniques that have been postulated, and in some cases tested, to change various aspects of the natural environment to stem anthropogenic climate change.

The main global system that geoengineering concentrates on is the atmosphere, with various proposals for adding or taking away components of this system being suggested to reduce the greenhouse effect.

Geoengineering has regained its popularity in recent years, due to many people feeling that insufficient progress has been made to cut carbon emissions.

However, while altering the climate to better suit ourselves may be desirable, it is also controversial and many scientists believe it should only be employed as a final recourse. These scientists choose instead to continue to focus on eradicating or at least minimizing the causes of anthropogenic climate change.

Types of Geoengineering

There are two broad categories that most geoengineering proposals are separated into, with many disparate techniques within these two categories.

Carbon dioxide removal

The first category is carbon dioxide removal, or CDR. This acts directly on the cause of global warming by removing CO₂ from the atmosphere. This is then stored in a certain place depending on the exact method used.

One method that has been implemented recently is the dumping of iron into the sea. The hope is that the phytoplankton algae that bloom massively once iron is added to the ocean will absorb vast quantities of CO₂ from the atmosphere, as they naturally require this to grow. Once the algae die (usually after about 3 weeks) they will sink to the bottom of the ocean, taking the carbon with them and thus storing it away from the atmosphere.

Further examples of techniques that fall under this umbrella term are listed below:

• Enhanced weathering of rocks
• CO₂ storage in soil
• CO₂ storage in vegetation
• Underground carbon storage

Solar radiation management (SRM)

This group of techniques aims to reduce the amount of light and radiation from the sun that hits the planet.

An example of SRM is the method of spraying particles into the air from a giant tethered balloon. This technique is aiming to mimic the effect of a volcanic eruption, which emits vast amounts of aerosols into the atmosphere which reflect sunlight into space.

It has been measured that huge volcanic eruptions, such as the eruption of Mount Pinatubo in 1991, can emit enough SO₂ to lead to several years of global cooling. It is thought that this could be replicated using balloons, planes, or stationary plants to pump similar amounts of SO₂ into the atmosphere, where it would be turned into fine sulphuric acid to reflect sunlight.

Other techniques that implement sunlight reflection to cool the planet include:

• Cloud whitening using water vapor
• Increased surface albedo
• Sun-blocking mirrors

The Benefits of Geoengineering

The main benefit of geoengineering is that it can help sustain the climate that we are used to, without the need for drastic changes to our standard of living by cutting carbon emissions.

Geoengineering could also be used as an aid to help ease the transition between dependence on fossil fuels and renewable technologies.

Few scientists are advocating the use of widespread geoengineering in the next few years. However, many suggest that these techniques should be the focus of considerable research now so that if the time comes when widespread deployment is required we will not be caught short.

Issues with Geoengineering

Geoengineering can be seen as a risky solution to climate change because the atmosphere is an inherently complex system that cannot be completely predicted. This means that once one problem has been solved another may be raised, even as a consequence of the presumed solution. For example, nobody is completely sure of the long-term environmental effects of pumping millions of tonnes of SO₂ into the atmosphere.

These techniques can also distract from efforts to cut anthropogenic emissions directly, leading to complacency towards climate change. The focus may also be taken away from climate adaption techniques such as climate proofing and clean energy technologies.

Furthermore, many techniques that are being suggested may tackle the problem of increasing planetary temperatures, but few consider other problems associated with climate change, such as the acidification of the ocean. For example, solar radiation management techniques may help reduce the temperature quickly during a climate crisis, but they do not reduce the amount of CO₂ in the atmosphere and hence do not deal with related issues.

An enlightening video from environmental scientist David Keith is shown below, further discussing the pros and cons of geoengineering.

Recently, some less risky or unpredictable geoengineering techniques have been proposed, however, these are relatively low-tech and localized. Examples include rewilding, where unused or inefficiently used land is enabled to return to local ecosystems through protection projects and the reintroduction of native plant and animal life, and the above-mentioned focus on sea algae with their high rates of photosynthesis.

This article was updated on 24^th February, 2020.

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