Geoengineering
From ClimateWiki
Geoengineering, also known as climate engineering, is the concept of applying planetary engineering to Earth, deliberately modifying the Earth's environment on a large scale. It aims to repair the effects of human-induced climate change.
Types of Strategies
Various types of geoengineering strategies have been proposed. The following are a few examples:
Solar radiation management:
Solar radiation management projects seek to reduce the amount of sunlight hitting the Earth and thus counteract global warming. They do not reduce greenhouse gas concentrations in the atmosphere, and thus do not address problems such as ocean acidification caused by these gases. The phenomenon of global dimming as a side-effect of fossil fuel use is widely known, and is not necessarily a geoengineering technique, also occurring naturally as a result of volcanoes and major forest fires. However, its deliberate manipulation is a tool of the geoengineer.
Solar radiation management projects often have the advantage of speed. While greenhouse gas remediation offers a comprehensive possible solution to climate change, it does not give instant results; for that, solar radiation management is required.
Techniques that fall into this category include:
Creating stratospheric sulfur aerosols
Ocean foams
Cool roof—using pale-coloured roofing and paving materials
Cloud reflectivity enhancement – using fine sea water spray to whiten clouds and increase cloud reflectivity.
Space sunshade—obstructing solar radiation with space-based mirrors or other structures
Cloud seeding of cirrus clouds, possibly using airliners
Greenhouse gas remediation:
Greenhouse gas remediation projects seek to remove greenhouse gases from the atmosphere, and thus tackle the root cause of global warming. They either directly remove greenhouse gases, or alternatively seek to influence natural processes to remove greenhouse gases indirectly. These projects offer a comprehensive solution to the problem of excess greenhouse gases in the atmosphere, but they will take many years to work fully. Many projects overlap with carbon capture and storage and carbon sequestration projects, and may not be considered to be geoengineering by all commentators.
Techniques in this category include:
Ocean nourishment including Iron fertilisation of the oceans
Creating biochar (anaerobic charcoal) and burying it to create terra preta
Bio-energy with carbon capture and storage
Carbon air capture to remove carbon dioxide from ambient air
Arctic geoengineering:
Various hydrological geoengineering projects aim to change the climate without directly or indirectly removing greenhouse gases, or directly influencing solar radiation. These principally act by limiting Arctic sea ice loss. Keeping the Arctic ice is seen by many commentators as vital, due to its role in the planet's albedo and in keeping methane, which is an important greenhouse gas, locked up in permafrost.
Heat transport:
The use of vertical ocean pipes to mix cooler deep water and warmer surface water has been proposed. This technology has also been suggested for the disruption of hurricanes by Bill Gates and others in a recent patent application. Modification of hurricanes may be considered weather modification rather than geoengineering, depending on the definition used.
Cost & Criticism
According to Alan Carlin as published in "Watt's Up With That?":
CO2 emissions reductions are economically unattractive since the few benefits remaining after the corrections for effects are quite unlikely to economically justify the much higher costs unless much lower cost geoengineering is used. However, the risk of catastrophic anthropogenic global warming appears to be so low that it is not currently worth doing anything to try to control it, including geoengineering.
Therefore, geoengineering may be a more financially responsible remediation effort, but, keeping in mind the minimal risk of global warming, the cost may not be worth enduring.
References
http://www.grida.no/publications/other/ipcc_tar/?src=/CLIMATE/IPCC_TAR/wg3/176.htm
Mitchell, D. L.; Finnegan, W. (2009). "Modification of cirrus clouds to reduce global warming". Environmental Research Letters 4 (4): 045102. doi:10.1088/1748-9326/4/4/045102.
http://www.cleverclimate.org/climate/25/motivation/
Zimov, S. A., et al. (2006), CLIMATE CHANGE: Permafrost and the Global Carbon Budget, Science, 312(5780), 1612-1613.
US Patent Application No. 20090177569, titled: “Water alteration structure risk management or ecological alteration management systems and methods” US Patent Application No. 20090175685, titled: “Water alteration structure movement method and system” US Patent Application No. 20090173801, titled: “Water alteration structure and system having below surface valves or wave reflectors” US Patent Application No. 20090173404, titled: “Water alteration structure and system” US Patent Application No. 20090173386
Vergano, Dan (2009-07-15). "Hurricane-calming technology? Bill Gates has a plan". USA Today. Retrieved 2009-07-23.
