Geoengineering is a term given to the application of technologies to actively modify the environment on a large scale in order to mitigate an undesirable change, such as increasing temperatures or rising sea levels. This is largely theoretical at this stage, with limited examples of applications having been implemented, mainly due to concerns over the ability to model and forecast all of the effects of a new forcing factor on the environment, which is an already highly complex and non-linear system. Examples include large mirrors in space to reflect solar irradiation, reducing the amount reaching the earth's surface and reducing temperatures; seeding of clouds to have the same effect (i.e. reduce solar irradiation); or the direct capture and transformation or storage of greehouse gases though industrial processes, or indirectly by, for example, seeding the oceans with iron, increasing their ability to absorb carbon dioxide.
Feedback loops in climate systems are discussed elsewhere on this site, and result from many interactions between the earth's land, ocean and atmospheric systems. Adding additional forcing factors into this mix risks creating unforeseen effects, with potentially significant adverse impacts on communities, ecosystems and biodiversity. Further, geoengineering raises questions of ethics related to human's right to intentionally change the climate, the implementation (with the potential for intended or unintended knock-on effects in different nations or regions), the global governance of geoengineering schemes and the intent behind such changes in each scheme. For example, what is the right baseline to aim for in making any changes, and to what extent is this seen as reducing the effects of man-made climate change vs. optimising the climate for a specific end? Further, such techniques have been critisised as being seen as an alternative to taking action to reduce emissions, as geoengineering is not addressing the root cause of the problem in the first place, and makes it less imperative to address over time; whilst others see geoengineering as a potential stop-gap given the conflict between an imminent need to reduce GHGs to avoid significant adverse climate change, and the longer time frame it is likely to take the world to re-structure the link between development and the drivers of economic growth and emissions.
