The termination problem refers to the issues that arise once geoengineering has ceased. It is probably best explained in the graphs below.
These graphs are taken from a paper by Ross and Matthews (2009) which discusses the potential for accelerated temperature increase following the cessation of geoengineering.
The first graph shows the expected temperature increase under a business as usual scenario (BAU). While the graph shows a considerable increase in temperature, this takes place over a relatively large time frame (relative to the second graph that is). The annual rate of warming is estimated between 0.015°C to 0.07°C.
The second graph shows a scenario in which geoengineering is implemented from 2020 but is subsequently stopped in 2059. The geoengineering successfully reduces the temperature change while it is in place, but once it has been stopped the annual rate of warming is estimated between 0.13°C to 0.76°C for the first few years, this then decreases to approximately 0.1°C per year within a decade of the cessation of geoengineering.
While the BAU scenario has an increase in temperature between 0.6°C to 5.1°C between 1990 and 2100 the Geoengineering scenario has an increase in temperature between 0.15°C and 4.5°C between 2060 and 2100.
The danger here is not just the absolute increase in temperature but the rate of change. The rate of temperature increase can be regarded as inversely proportional to the the ability of an ecosystem to adapt to climate change. Ross and Matthews (2009) propose that the short-term increased rate of warming following the termination of geoengineering "would be sufficient to severely stress the adaptive capacity of many species and ecosystems, especially if preceded by some period of engineered climate stability".
The authors conclude that geoengineering should be coupled with mitigation efforts, specifically the reduction of greenhouse gas emissions, and it should not be considered as an alternative to reducing emissions.
Before considering geoengineering as plan of action to tackle global environmental change it is important to consider the commitment that it demands. Once it has been put in place it becomes very difficult to undo. If the side-effects are less manageable or are more severe than was anticipated, or if there is an unavoidable technological failure and geoengineering loses favour with its creators and advocates, well then this feat of human endeavour starts to seem monstrous and this monster doesn't like rejection.
Happy Halloween!
These graphs are really quite worrying! Do you think with results like this geoengineering could ever be excepted globally?
ReplyDeleteI totally agree that coupling with mitigation is very important. Will it make it harder to track mitigation results with the geoengineering making an impact too?
Completely agree with Nathen - the second graph is fairly worrying and the commitment needed to continue with geoengineering once started seems huge! I've come across an article that shows the methods and locations where geoengineering has to take place (attached link at bottom) - I know you'll cover the potential impacts, but have you come across anything or in your opinion how would the costs be shared out as some are quite expensive?
ReplyDeletehttp://www.newscientist.com/article/mg22029382.500-terraforming-earth-geoengineering-megaplan-starts-now.html#.UnoL-_k9LZ0
The graphs are shocking but I do still think that there could be a place for geoengineering. The graphs depict a scenario where geoengineering is terminated abruptly. If it is slowly phased out in a controlled way, and if C02 emissions are reduced, then the feedback would not be so severe. But there are two important caveats to this:
ReplyDeleteFirstly, it may not be possible to avoid sudden failure of geoengineering.
Secondly, I find it difficult to imagine an economic and political environment with the impetus to continue cutting emissions when geoengineering is working successfully and temperature change has been reduced.
I haven't yet come across any concerns over tracking the results of mitigation and geoengineering if they are in place simultaneously, but there are concerns that it could be difficult to distinguish between environmental changes from the side-effects of geoengineering and environmental changes from global warming. Disagreements of this nature could potentially strain the international co-operation that would be required for geoengineering.
The cost of geoengineering is another issue that will require considerable international co-operation, obviously some nations would be better able to fund geoengineering, but the impacts are global and so regardless of GDP every nation has a stake and therefore should have a say. How the bill gets split remains to be seen.