Reducing Global Catastrophic Risks from Unseen Climate Extremes

极端的气候会造成毁灭性的破坏。最严重的事件已造成数百万人死亡，并通过复杂的级联造成深远的其他影响，例如，在1970年博拉气旋造成50万人死亡后，东巴基斯坦崩溃。随着气候变暖到人类历史上从未经历过的程度，前所未有的极端情况的可能性也在增加，要么是因为熟悉的灾害，如达到不熟悉的强度的热浪，要么是新事件的到来--例如，一场强大的热带气旋首次摧毁了波斯湾高度发达的海岸线。这些新的威胁是“看不见的”：它们置身于所有人类经验之外，因此它们的潜在影响非常不确定。向上推断历史上最类似事件的后果可能会对预期提供非常保守的估计，因为意外因素可能会对一个毫无准备的社会造成更大的影响。因此，新的气候极端现象可能表现为全球灾难风险(GCR)--造成全球范围的影响，导致至少1000万人死亡或至少造成10万亿美元的损失--值得紧急关注。地平线上最令人担忧的未知极端是如此严重的热浪的出现，以至于在人类历史上，大气第一次成为大片人口稠密地区的热源而不是汇。这样的条件意味着，无论身体状况、水分水平或与球迷接触的途径如何，长时间暴露在空气中(几个小时)将是致命的。我们确实知道，在全球变暖充分的情况下，这些事件将会发生，而且它们最早可能在本世纪变得广泛；但确切地说，这些事件在哪里处于危险之中，以及何时可能出现威胁，还不是很好地了解。这种事件的潜在社会影响几乎完全未知。例如，如果大气变成热沉，史无前例的死亡是不可避免的吗？如果是这样的话，是否会因为地方被遗弃而引发大规模移民？或者，风险最高的社区能否对这种极端高温具有弹性？该奖学金将解决我们对看不见的热浪的理解中的这些关键研究空白。通过一个雄心勃勃的物理科学计划，它将提供新的见解，以了解地区需要变暖多少才能经历超出人类承受能力的高温。它聚焦于世界上最热的城市之一(巴基斯坦雅各巴德)，将努力解决区域范围内的热量如何在人们家中表现出来的复杂性，最终将未来的气候模型预测与人们可能在社区内经历的条件联系起来。通过一个同样雄心勃勃的社会科学研究计划，该奖学金还将解决这样一个问题：社区对未来热浪的适应能力有多强，以及通过适应可以在多大程度上加强这一能力。与此同时，跨学科联谊会团队还将扩大范围，探索哪些其他未曾见过的极端气候对我们的未来构成最大威胁，哪些--可能具有全球气候变化的潜力--应该优先用于紧急降低风险的工作。识别新威胁的挑战尤其困难，因为它要求我们克服历史的认知偏见，识别可能发生的更广泛的极端事件，同时考虑到气候变化。该联谊会将使用“自上而下”(以灾害为中心)的技术来克服这一问题，利用历史事件和气候模型模拟一起绘制出物理上可信的威胁的领域。自下而上(以脆弱性为中心)的方法反过来将启发和缩小对这一非常大的阶段空间的搜索。这些观点一旦得到完善，将构成一个新的框架，以系统地识别和减少来自最危险的未知气候极端情况的风险。

Climate extremes can cause devastation. The most severe events have killed millions and, through complex cascades, resulted in profound additional impacts, for example the collapse of East Pakistan following the 0.5 million deaths from the 1970 Bhola Cyclone. As the climate warms to a level not experienced in human history, the potential for unprecedented extremes is also growing, either from familiar hazards like heatwaves reaching unfamiliar intensities, or the arrival of events that are new in character -- for example the first time a powerful tropical cyclone ravages the highly-developed shorelines of the Persian Gulf. Such novel threats are 'unseen': they sit outside all human experience, and their potential impacts are, therefore, highly uncertain. Upward extrapolation of the consequences from the most similar events in history may provide a very conservative estimate of what to expect, as the element of surprise could cause even greater impacts on a society that is unprepared. The potential for novel climate extremes to manifest as Global Catastrophic Risks (GCRs) -- with world-wide impacts, killing at least 10 million people or causing at least $10 trillion of damages -- therefore deserves urgent attention. The most concerning unseen extreme on the horizon is the emergence of heatwaves so severe that, for the first time in human history, the atmosphere becomes a heat source rather than a sink over large, well-populated regions. Such conditions mean that regardless of fitness, levels of hydration, or access to fans, prolonged exposure (in the order of hours) would be deadly. We do know that these events will occur given sufficient global warming, and that they may become widespread as early as this century; but precisely where is at risk and how soon the threat may emerge is not well understood. The potential societal impacts of such an event are almost completely unknown. For example, is unprecedented mortality inevitable if the atmosphere becomes a heat sink? If so, might it trigger mass migration due to place abandonment? Or could the most at-risk communities become resilient to such extreme heat?The Fellowship will address these critical research gaps in our understanding of unseen heatwaves. Through an ambitious program of physical science it will provide new insight into how much warming is required for regions to experience heat beyond human tolerance. Focussing on one of the hottest cities in the world (Jacobabad, Pakistan), it will grapple with the complexity of how heat at regional scales manifests within people's homes, finally joining up future climate model projections with the conditions that people are likely to experience within their community. Through an equally ambitious program of social science research, the Fellowship will also tackle the question of how resilient communities may be to these future heatwaves, and the extent to which that could be strengthened through adaptation. At the same time, the interdisciplinary Fellowship team will also zoom out to explore what other unseen climate extremes most threaten our future, and which -- perhaps with GCR potential -- should be prioritised for urgent risk reduction efforts. This challenge of identifying novel threats is particularly difficult because it requires that we overcome the cognitive bias of history to identify the much wider set of extreme events that could have occurred, whilst also accounting for a changing climate. It will be overcome by the Fellowship using 'top-down' (hazard-centred) techniques, whereby historical events and climate model simulations are used together to map out the domain of physically-plausible threats. Bottom-up (vulnerability-centred) approaches will in turn inspire and narrow the search of this very large phase space. These perspectives, once refined, will constitute a new framework to systematically identify, and reduce risk, from the most dangerous unseen climate extremes.