The Net-Zero Emissions Challenge: Quantifying unintended climate feedbacks from large-scale deployment of land-based CO2 removal strategies

在过去的几十年里，大气中的二氧化碳（CO2）浓度迅速增加，以至于地球的温度还没有完全适应新的变暖气候。这意味着，即使二氧化碳和其他温室气体（GHG）的排放立即减少到零，地球仍将过渡到更温暖的气候。2015年，在巴黎签署了一项雄心勃勃的协议，将全球变暖限制在2摄氏度以下，并继续努力将其限制在1.5摄氏度以内。全球气温已经比工业化前水平上升了1摄氏度以上。用于了解未来气候变化的计算机模拟表明，履行《巴黎气候协定》既需要大幅减少温室气体排放，也需要使用二氧化碳去除（CDR）策略，从而在2100年前实现接近零排放或负排放。为了实现这一目标，到2050年，社会将被要求从大气中去除比排放更多的温室气体。造林/再造林、湿地恢复、增强风化和生物能源作物是四种拟议的陆基CDR战略，它们寻求通过加速在自然地球循环中已经发生的自然过程来消除生物圈中的二氧化碳。这些CDR战略得到联合国的承认，技术准备程度各不相同。然而，由于这些CDR策略、土地和大气之间复杂的相互作用，未确定的环境风险（例如，非co2温室气体排放增加）尚未得到充分了解和量化。因此，虽然这些策略实际上可以从大气中去除二氧化碳，但它们可能无法有效地阻止未来的变暖。了解CDR工作的有效性对于帮助社会和决策者设计应对气候变化的减缓和适应方法至关重要。该奖学金建议英国首次进行综合研究，具体量化与大规模部署这四种陆基CDR战略相关的环境风险。为了应对这一重要挑战，该研究金将开发一个协调的跨学科地球系统科学框架，该框架将把来自实地实验、地面和卫星地球观测的新信息与下一代计算机模拟相结合。该奖学金还将利用我在大气-生物圈-气候相互作用方面强大的跨学科研究背景，以及国际公认的合作者和英国合作伙伴、英国政府和世界野生动物基金会的专业知识，建立一个世界领先的小组，以了解人类对气候系统的干预，这将指导社会和政策制定者走向实现净零排放的最合适途径。

Over the past decades, carbon dioxide (CO2) concentrations in the atmosphere have increased rapidly, to the point that the Earth's temperature has not fully adjusted to the new warmer climate. This means that even if carbon dioxide and other greenhouse gas (GHG) emissions were instantaneously reduced to zero, the Earth would still transition to a warmer climate. In 2015, an ambitious agreement was signed in Paris to limit global warming below 2C degrees and pursue efforts to limit it to 1.5C. Global temperatures have already increased by more than 1C above pre-industrial levels. Computer simulations, used to understand what can happen to the climate in the future, have shown that delivering on the Paris Climate Agreement will require both drastic reductions of GHG emissions and use of carbon dioxide removal (CDR) strategies leading to near-zero or negative emissions by 2100. To achieve this goal, society will be required, by 2050, to remove more GHGs from the atmosphere than those released.Afforestation/reforestation, wetland restoration, enhanced weathering and bioenergy crops are four proposed land-based CDR strategies that seek to remove CO2 in the biosphere by accelerating natural processes that are already occurring within the natural Earth cycle. These CDR strategies are recognized by the United Nations and have varying levels of technological readiness. However, unidentified environmental risks (e.g., increased non-CO2 GHG emissions) due to complex interactions between these CDR strategies, land and atmosphere are not fully understood and quantified. Therefore, while these strategies may practically remove CO2 from the atmosphere, they might not effectively stop future warming. Understanding the effectiveness of CDR efforts is critical to help society and policy makers design mitigation and adaptation approaches for tackling climate change. This Fellowship proposes the UK first integrated study for quantifying specifically the environmental risks associated with the large-scale deployment of these four land-based CDR strategies. To address this important challenge, this Fellowship will develop a coordinated cross-disciplinary earth system science framework, which will combine new information from field experiments and surface and satellite earth observations with the next generation of computer simulations. This Fellowship will also leverage my strong interdisciplinary research background in atmosphere-biosphere-climate interactions and the expertise of internationally recognized collaborators and UK partners, the UK Government and the World Wildlife Fund to establish a world-leading group for understanding human intervention in the climate system, which will guide society and policy makers towards the most appropriate pathways to reach net-zero emissions.