Geoengineering is a broad term which covers various techniques which have been postulated, and in some cases tested, to change various aspects of the natural environment in order 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 had a recent resurgence in popularity in recent years, due to many people feeling that insufficient progress has been made with regards to cutting carbon emissions. Altering the climate to better suit ourselves may be a desirable goal, but it is also controversial and many scientists believe it should only be employed as a final recourse.
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
Types of Geoengineering
There are two broad categories that current geoengineering techniques 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 such 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)
As the name suggests, 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 amount of aerosols into the atmosphere which can reflect sunlight back 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 though 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 in order to cool the planet include:
- Cloud whitening using water vapour
- Increased surface albedo
- Sun-blocking mirrors
The Benefits of Geoengineering
The main benefit of geoengineering of course 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, but 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 infinitely complex system that cannot be completely predicted, meaning that once one problem has been solved another may raise its head. 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 with regards to climate change. Focus may also be taken away from climate adaption techniques such as climate proofing and clean energy technologies such as wave power.
Furthermore, many techniques that are being suggested may tackle the problem of increasing planetary temperatures, but few take into account other problems associated with climate change, such as the acidification of the ocean. For example, solar radiation management techniques may help reduce temperature quickly in the event of 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.
Sources and Further Reading
- Geoengineering: Risks and benefits, BBC News, 24/08/2012
- Integrated Assessment of Geoengineering Proposals (IAGP)
- Geoengineering the climate: science, governance and uncertainty, The Royal Society
- Geoengineering Could Backfire, Make Climate Change Worse, Wired Science, 16/07/2012
- Oxford Geoengineering Programme
- Is Geoengineering the Answer to Climate Change? Smithsonian Magazine, 31/08/2012
- Experiment would test cloud geoengineering as way to slow warming, University of Washington, 20/08/2012
- Dumping iron at sea can bury carbon for centuries, study shows, The Guardian, 18/07/2012