Reducing Global Catastrophic Risks from Unseen Climate Extremes

极端气候可能造成破坏。最严重的事件造成数百万人死亡，并通过复杂的级联效应产生了深远的额外影响，例如，1970年波拉气旋造成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，发生前所未有的极端事件的可能性也在增加，要么是熟悉的危险，如热浪达到不熟悉的强度，要么是新的事件的到来，例如第一次强大的热带气旋蹂躏波斯湾高度发达的海岸线。这种新的威胁是“看不见的”：它们位于所有人类经验之外，因此其潜在影响是高度不确定的。从历史上最相似的事件中向上推断后果，可能会对预期的结果做出非常保守的估计，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，新的极端气候可能表现为全球灾难性风险-具有世界范围的影响，造成至少1 000万人死亡或至少10万亿美元的损失-值得紧急关注。地平线上最令人担忧的看不见的极端现象是出现了如此严重的热浪，以至于人类历史上第一次，大气层成为热源，而不是人口稠密地区的热源。这样的条件意味着，无论健康状况如何，水合程度如何，或者是否能接触到粉丝，长时间的接触（以小时为单位）都是致命的。我们确实知道，如果全球变暖足够严重，这些事件就会发生，而且它们可能早在本世纪就变得普遍;但确切地说，哪里有风险，以及这种威胁多久会出现，我们还不清楚。这种事件的潜在社会影响几乎完全未知。例如，如果大气层成为散热器，空前的死亡率是否不可避免？如果是这样的话，它是否会因地方放弃而引发大规模移民？或者，最危险的社区是否能适应这种极端高温？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。通过一项雄心勃勃的物理科学计划，它将提供新的见解，了解需要多少变暖才能让地区经历超出人类耐受范围的高温。该项目聚焦于世界上最热的城市之一（巴基斯坦的雅各布巴德），将努力解决区域尺度的热量如何在人们的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在社区内可能经历的条件结合起来。通过一个同样雄心勃勃的社会科学研究计划，该奖学金还将解决社区如何应对未来热浪的问题，以及通过适应可以在多大程度上加强这一点。与此同时，跨学科研究员团队还将探索其他哪些看不见的极端气候对我们的未来威胁最大，以及哪些-也许具有GCR潜力-应该优先考虑紧急的风险降低工作。识别新威胁的挑战特别困难，因为它要求我们克服历史的认知偏见，以确定可能发生的更广泛的极端事件，同时也考虑到气候变化。它将由研究金使用“自上而下”（以灾害为中心）的技术来克服，即历史事件和气候模型模拟一起使用，以绘制出物理上合理的威胁领域。自下而上（以能力为中心）的方法将反过来激发和缩小对这个非常大的相空间的搜索。这些观点一旦完善，将构成一个新的框架，以系统地确定和减少最危险的看不见的极端气候的风险。

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.