LEarning About Cloud modification under risk and uncertainty: Investigation of feasibility, traceability, Incentives and de-centralised governance of limited-area climate mitigation (LEAC - II)

气候工程（CE）已被提议作为应对危险的全球变化的最后手段。然而，在考虑可能的实施方式，甚至是大型现场实验时，会出现许多问题。然而，CE不是一个非此即彼的决定，从现场实验到CE应用的过渡是模糊的。对未来可能实施CE措施的现实评估需要认真考虑有限区域CE的可能性。云的变化施加了一个辐射强迫，该强迫局限于喷洒区域。这是一个必要的，但不是充分的条件，如近地面温度的气候参数的局部反应。第一个问题是，国家或国家俱乐部利用有限区域CE的动机和可能性是什么。为此，我们将估计与气候相关变量的经济偏好在空间上的相关程度。取决于当地操纵相关气候变量的可行性，并考虑到世界各地区对这些变量的偏好，下一个问题是，在缺乏气候政策全球合作的情况下，国家或国家俱乐部可能在多大程度上利用有限区域的CE，以及这将在多大程度上影响温室气体减排努力。对有限区域行政竞争的监管范围取决于是否有可能将预期结果归因于行政竞争措施，并排除目标区域以外的损害。我们将研究这一建设与检测和归因研究的经验，利用新的方法，利用集合气候预报在短时间尺度。在LEAC-II中，我们最终的目标是探索在非点源污染控制理论的基础上起草一个国际监管机制的潜力，这将导致帕累托改进相比，不协调的结果。LEAC-II将处理以下问题：1.可行性：在多大程度上有可能对局部强迫产生局部气候响应？ 2.激励措施：经济偏好与气候变量的空间相关性如何？3.经济影响：当各国以不协调的方式实施有限区域的碳排放和减少温室气体排放时，有限区域的碳排放可能对福利产生什么影响？4.可追溯性：如何检测和归因CE措施的局部效应，并拒绝目标区域以外的气候事件受到CE措施影响的假设？- 这将根据总体建模，为社会经济评估提供概率分布。治理：鉴于可预测性和可追溯性的不确定性，如何最有效地监管有限区域的CE？

Climate engineering (CE) has been proposed as a means of last resort to combat dangerous global change. However, numerous concerns arise when considering a possible implementation, or even a large field experiment. Yet, CE is not an either-or decision, and the transition from a field experiment to the application of CE is blurred. A realistic assessment of the potential future implementation of CE measures needs to seriously consider the possibility of limited-area CE. The modification of clouds exerts a radiative forcing that is localised to the region of spraying. This is a necessary, but not sufficient condition for a localised response of climate parameters such as near-surface temperature. A first question is, what could be the incentives and possibilities for countries or clubs of countries to utilise limited-area CE. To this end, we will estimate how strongly the economic preferences with respect to climate-related variables are correlated in space. Depending on the feasibility of a local manipulation of relevant climate variables, and given the preferences of the regions of the world with respect to these variables, a next question is to what extent countries or clubs of countries might make use of limited-area CE, and to what extent this would influence greenhouse gas mitigation efforts, in the absence of global cooperation on climate policy. The scope for regulation of limited-are CE depends on the possibility to attribute intended outcomes to CE measures and to exclude damages outside the targeted area. We will study this building on the experience with detection and attribution studies, making use of novel approaches exploiting ensemble climate forecasts at short timescales. In LEAC-II we finally aim at exploring the potential to draft an international regulation mechanism based on the theory of non-point source pollution control that would lead to a Pareto-improvement compared to the uncoordinated outcome. LEAC-II will address the following questions:1. Feasibility: To which extent is it possible to generate a localised climate response to a localised forcing? 2. Incentives: What is the spatial correlation of economic preferences with respect to climate variables? 3. Economic implications: What are possible welfare implications of limited-area CE when countries implement limited-area CE and mitigate greenhouse gas emissions in an uncoordinated way?4. Traceability: What does it take to detect and attribute a localised effect of a CE measure, and to reject the hypothesis that climate events outside the targeted area are affected by the CE measure? - Based on ensemble modelling, this will provide probability distributions for the socio-economic assessment.5. Governance: How to regulate limited-area CE most efficiently, given the uncertainties in predictability and traceability?