# The Buying Time Argument within the Solar Radiation Management Discourse
## 6 Summary, Conclusions, Suggestion  
Let us sum up our entire reflective argument on BT-based permissibility of SAI. If criticism against the emergency argument is accepted (as we do), BTA is the \"last man standing\" in favor of SAI. The BTA has some initial moral (\"humanitarian\") force and it can be instantiated with models and scenarios. If BTA, however, fails, SAI has lost moral grounds completely. We summarize our main findings in order to judge upon the if-clause. BTA is both a peak-shaving and a reducing-pressure strategy. It addresses both primary and secondary climate goals. BTA as a peak-shaving proposal refers in a morally decent way to a conditional and imperfect second-best solution with contestable side effects. BTA-based SAI might be helpful in terms of adaptation, either broadly or narrowly conceived. SAI might also be calculated within an overall \"least cost planning\" model. The strongest version of BTA would be both humanitarian with respect to vulnerable groups (\"peak-shaving\") and effective with respect to reducing opportunity costs of a long process of decarbonization (\"least cost planning\"). This version might be strong enough to shift the argumentative burden upon opponents who may further on argue with uncertain side effects, missing governance etc. Since the arguments on the contra-side are contested as well [56], BTA-based SAI does not look completely impermissible. Such buying time deployment of SAI, however, must be able to meet some requirements. We tried to identify crucial requirements in the previous sections and discussed them in some detail. Those are:  
* SAI is conditional upon ambitious abatement;
* It is just an amendment, not a substitute;
* SAI must be finite;
* SAI must not fall to general moral constraints and must be apt for just governance. The conditional of complementarity to abatement removes all cost estimates showing that SAI is cheaper than abatement. In addition to abatement, things look differently. Moreover, there is legitimate distrust in nations which do not contribute to global abatement policies but start research on SAI, because they may see SAI as imperfect substitute for abatement. Whether those requirements can be met remains empirically underdetermined. We trust that the predictive capabilities of models are more than prophecy, yet large uncertainty prevails (see [57; 58]). We cast doubts on whether the requirements of fair global governance can be met. Concerns about hubris also remain. The hubris argument comes in full force, if some essential requirements of the BTA remain underdetermined--as they do! A non-metaphysical hubris argument might be conjoined with concerns about moral hazards, hazardous side effects, and uncertain exit options. [PERSON] [9] is rightly pointing at the time of ecological restoration hopefully following climate engineering. It seems desirable that this time should come as soon as possible. If so, the requirement of finitude of SAI seems crucial. Time spans of hundreds of years are unpredictable and unacceptable. Proponents of BTA concede that SAI should be minimized in terms of duration and magnitude of Sulphur. Minimizing SAI deployment under the conditional of complementarity to abatement and with realistic assessment of full costs may result in recognizing that SAI is not just risky, but also highly expensive. An analogy to nuclear energy might be at place. If one combines BTA with outlooks for an ecological civilization after geoengineering [9], one must take into accounts whether SAI technologies are neutral with respect to such transition. Technologies are not neutral, and climate technologies especially must be shaped in accordance with a sustainable future [59]. SAI research, testing, and deployment over some decades must not involve path dependencies against the modes of societal and cultural change we ultimately wish to see. This is a non-trivial assumption. [PERSON] et al.