Negative Emission Technologies and the food-energy-water-neXus (NETX)

如果二氧化碳排放量继续上升，气候变化将对全球粮食和水供应、生态系统、城市和沿海社区产生不利影响。虽然减少化石燃料将是减少大气二氧化碳的关键一步，但负排放技术(NETS)可以帮助实现排放目标。在燃烧过程中，二氧化碳可以被提取、运输和储存在地质储存库中--这是碳捕获和储存(CCS)的过程。将生物能源与CCS(BECCS)相结合可能会导致二氧化碳的负排放。BECCS很有吸引力，因为它可以从大气中净去除二氧化碳，同时还提供了一种可再生能源。然而，BECCS需要大量的土地承诺，并将对食物和水的供应产生影响。这项工作的重点是BECCS，并解决了规划全球和全国范围内的生物能源作物分布的挑战。IPCC的绝大多数情景保持在2摄氏度以下，在21世纪使用NET。尽管生物能源作物和BECC是情景(由综合评估模型(IAM)产生)的重要组成部分，但即使是最复杂的IAM中的作物也只对气候的平均变化做出反应。这导致了建模框架的不一致：在气候变化实际上会降低其有效性的地区，IAM可以假设生物能源作物在减少二氧化碳和生产能源方面是有效的。地球系统模型(ESM)代表了大气、海洋、海冰和陆地表面的动态。它们可以解释土地利用变化引起的生物物理(即反照率和潜热通量的变化)和生物地球化学(即温室气体的吸收或释放)反馈。它们是研究气候时空变异性对粮食、能源和水关系未来影响的唯一工具。然而，IPCC上一份报告中使用的ESM充其量只占一种普通作物类型，没有区分生物能源作物和粮食作物。如果生态系统中没有明确的生物能源作物，气候变化的影响不会影响到国际管理系统中假定的食物、能源和水资源。迫切需要在耦合气候模拟中预测生物能源作物的生产力，以了解一系列气候变化对生产力的影响，以及对粮食作物生产力、能源生产和水资源供应的相关影响。在这个项目中，我将包括英国ESM的第一代和第二代生物能源作物的代表，并调查气候变化对全球和地区(英国)生产力的影响。这项工作将评估通过生物能源作物负排放二氧化碳作为气候变化下有效的气候缓解战略的可行性，并为将气候变化和气候变化缓解对生物能源生产、食品和水资源供应的影响降至最低的决策提供数据支持。该项目的成果将通过更好的规划，并为平衡减少气候变化与养活我们日益增长的全球人口的挑战提供对社会负责的建议，从而提高粮食/水/能源关系对气候变化和气候多变性的适应能力。

If CO2 emissions continue to rise, climate change will adversely affect global food and water availability, ecosystems, cities, and coastal communities. While reduction of fossil fuels will be an essential step for reducing atmospheric CO2, Negative Emission Technologies (NETs) can help meet emission targets. During combustion, CO2 can be extracted, transported, and stored in geologic repositories - this is the process of Carbon Capture and Storage (CCS). Combining bioenergy with CCS (BECCS) could result in negative emissions of CO2. BECCS is attractive since it results in a net removal of CO2 from the atmosphere while also providing a renewable source of energy. However, BECCS requires a large commitment of land and will have impacts on food and water availability. This work focuses on BECCS and addresses the challenges for planning a global and nationwide distribution of bioenergy crops.The vast majority of IPCC scenarios that remain below 2 degrees C makes use of NET in the 21st century. Although bioenergy crops and BECCS are an essential component of the scenarios (produced by Integrated Assessment Models, or IAMs), the crops in even the most sophisticated IAMs only respond to mean changes in climate. This results in an inconsistency in the modelling framework: the IAMs can assume bioenergy crops are effective at drawing down CO2 and producing energy in a region where actually climate change will reduce their effectiveness. Earth System Models (ESMs) represent the dynamics of the atmosphere, oceans, sea ice, and land surface. They can account for biophysical (i.e. changes to albedo and latent heat fluxes) and biogeochemical (i.e. uptake or release of greenhouse gases) feedbacks due to land use change. They are the only tool available to investigate future impacts of spatial and temporal variability in climate on the food, energy, and water nexus. However, the ESMs used in the last IPCC report only accounted for a generic crop type at best, not differentiating between bioenergy and food crops. Without an explicit representation of bioenergy crops in ESMs, the effects of climate change do not feedback to affect the food, energy, and water resources assumed to be true in the IAMs. There is an urgent need for predicting the productivity of bioenergy crops in a coupled climate simulation, to see the impact of a range of climate change on the productivity, and associated impacts on food crop productivity, energy production, and water availability. In this project, I will include representations of first and second generation bioenergy crops in the UK ESM, and investigate the impacts of climate change on the productivity at the global and regional (for the UK) level. This work will assess the viability of negative emissions of CO2 through bioenergy crops as an effective climate mitigation strategy under a changing climate, and provide data to support decisions that will minimize the impacts of both climate change and climate change mitigation on bioenergy production, food, and water availability. The outcomes of this project will enhance the resilience of the food/water/energy nexus to climate change and climate variability through better planning, and providing socially responsible recommendations for balancing the challenges of reducing climate change with feeding our growing global population.