Our carbon-intensive economy has led to an average temperature rise of 1 °C since pre-industrial times. As a consequence, the world has seen increasing droughts, significant shrinking of the polar ice caps, and steady sea-level rise. To stall these issues’ worsening further, we must limit global warming to 1.5 °C. In addition to the economy’s decarbonization, this endeavour requires the use of negative-emissions technologies (NETs) that remove the main greenhouse gas, carbon dioxide, from the atmosphere. While techno-economic feasibility alone has driven the definition of negative-emissions solutions, NETs’ diverse, far-reaching implications demand a more holistic assessment. Here, we present a comprehensive framework, integrating NETs’ critical performance aspects of feasibility, effectiveness, and side impacts, to define the optimal technology mix within realistic outlooks. The resulting technology portfolios provide a useful new benchmark to compare carbon avoidance and removal measures and deliberately choose the best path to solve the climate emergency. 相似文献
Today, a large amount of knowledge is available concerning various sites of potential high active waste (HAW) repositories in salt media. Domal Zechstein salt formations have been examined at several sites in Germany. Extensive R&D work was initiated in the former Asse Salt Mine in order to explore the suitability of salt for waste isolation by laboratory tests, theoretical studies and in-situ tests with test results forming a technological base for future repository development.
Resulting from the inhomogeneity of salt structures the demanded safety of a permanent repository for radioactive wastes can be demonstrated only by a specific site analysis in which the entire system, “the geological situation, the repository, and the form and amount of the wastes” and their interrelationships are taken into consideration.
The site analysis has three essential tasks: (1) Assessment of the thermomechanical load capacity of the host rock, so that deposition strategies can be determined for the site; (2) Determination of the safe dimensions of the mine (e.g. stability of the caverns and safety of the operations); and (3) Evaluation of the barriers and the long-term safety analysis for the authorization procedure.
The geotechnical stability analysis is a critical part of the safety assessment. Engineering–geological study of the site, laboratory and in situ-experiments, geomechanical modelling, and numerical static calculations comprise such an analysis.
Within a scenario analysis — according to the multi-barrier principle, the geological setting is checked to be able to contribute significantly to the waste isolation over long periods. The assessment of the integrity of the geological barrier can only be performed by making calculations with geomechanical and hydrogeological models. The proper idealization of the host rock in a computational model is the basis of a realistic calculation of stress distribution and excavation damage effects. The determination of water permeability along discontinuities is necessary in order to evaluate the barrier efficiency of each host rock.
In this paper some important processes for the performance assessment are described, namely creep and fracturing, permeability and infiltration, and halokinesis and subrosion.
For the future, the role and contributions of geoscientific and rock mechanics work within the safety assessment issues (e.g. geomechanical safety indicators) must be identified in greater detail, e.g. considerations of geomechanical natural analogy for calibration of constitutive laws. 相似文献
Due to the fear of the consequences of climate change, many scientists today advocate the research into—but not deployment of—geoengineering, large-scale technological control of the global climate, to reduce the uncertainty around its efficacy and harms. Scientists propose in particular initiating field trials of stratospheric aerosol injection (SAI). This paper examines how the meanings of geoengineering experimentation, specifically SAI field trials, are reconfigured in the deliberation of the lay public. To this end, we conducted focus groups with Japanese citizens in June 2015 on the geoengineering concept and SAI field trials. Our main findings are as follows: the ‘climate emergency’ framing compelled the lay public to accept, either willingly or reluctantly, the need for ‘geoengineering research’; however, public discourse on SAI field trials was ambiguous and ambivalent, involving both tensions and dilemmas in understanding what the SAI field trial is for and about. Our results exhibit how the lay public wrestles with understanding the social, political, and ethical implications of SAI field trials in multiple dimensions, namely, accountability, controllability, predictability, and desirability. The paper argues that more clarity in the term ‘geoengineering research’ is needed to facilitate inclusive and pluralistic debates on geoengineering experimentation and not to preemptively arrive at a consensus that ‘we need more research.’ We conclude that ambivalence about both the pros and cons of geoengineering experimentation seems to be enduring; thus, instead of ignoring or repressing it, embracing ambivalence is required to keep the geoengineering debate democratic and inclusive. 相似文献
ABSTRACTConsideration of solar geoengineering as a potential response to climate change will demand complex decisions. These include not only the choice of whether to deploy solar engineering, but decisions regarding how to deploy, and ongoing decision-making throughout deployment. Research on the governance of solar geoengineering to date has primarily engaged only with the question of whether to deploy. We examine the science of solar geoengineering in order to clarify the technical dimensions of decisions about deployment – both strategic and operational – and how these might influence governance considerations, while consciously refraining from making specific recommendations. The focus here is on a hypothetical deployment rather than governance of the research itself. We first consider the complexity surrounding the design of a deployment scheme, in particular the complicated and difficult decision of what its objective(s) would be, given that different choices for how to deploy will lead to different climate outcomes. Next, we discuss the on-going decisions across multiple timescales, from the sub-annual to the multi-decadal. For example, feedback approaches might effectively manage some uncertainties, but would require frequent adjustments to the solar geoengineering deployment in response to observations. Other decisions would be tied to the inherently slow process of detection and attribution of climate effects in the presence of natural variability. Both of these present challenges to decision-making. These considerations point toward particular governance requirements, including an important role for technical experts – with all the challenges that entails.Key policy insights
Decisions about solar geoengineering deployment will be informed not only by political choices, but also by climate science and engineering.
Design decisions will pertain to the spatial and temporal goals of a climate intervention and strategies for achieving those goals.
Some uncertainty can be managed through feedback, but this would require frequent operational decisions.
Some strategic decisions will depend on the detection and attribution of climatic effects from solar geoengineering, which may take decades.
Governance for solar geoengineering deployment will likely need to incorporate technical expertise for making short-term adjustments to the deployment and conducting attribution analysis, while also slowing down decisions made in response to attribution analysis to avoid hasty choices.
Ocean urea fertilization is one geoengineering proposal aimed at not only reducing the atmospheric levels of carbon dioxide but also increasing fish populations in nutrient poor areas of the ocean. Theoretically ocean fertilization promises great benefits but there is also the possibility of serious environmental damage to consider. The nature of ocean urea fertilization means it is more likely to be carried out in coastal waters, providing States with different powers to enforce their laws compared to ocean iron fertilization which is more suitable to waters beyond national jurisdiction. This paper considers the process and effect urea, when used for the purpose of ocean fertilization, may have on the marine environment as well as the social implications, particularly for coastal and island people in developing nations. 相似文献
Solar radiation modification (SRM, also termed as geoengineering) has been proposed as a potential option to counteract anthropogenic warming. The underlying idea of SRM is to reduce the amount of sunlight reaching the atmosphere and surface, thus offsetting some amount of global warming. Here, the authors use an Earth system model to investigate the impact of SRM on the global carbon cycle and ocean biogeochemistry. The authors simulate the temporal evolution of global climate and the carbon cycle from the pre-industrial period to the end of this century under three scenarios: the RCP4.5 CO2 emission pathway, the RCP8.5 CO2 emission pathway, and the RCP8.5 CO2 emission pathway with the implementation of SRM to maintain the global mean surface temperature at the level of RCP4.5. The simulations show that SRM, by altering global climate, also affects the global carbon cycle. Compared to the RCP8.5 simulation without SRM, by the year 2100, SRM reduces atmospheric CO2 by 65 ppm mainly as a result of increased CO2 uptake by the terrestrial biosphere. However, SRM-induced change in atmospheric CO2 and climate has a small effect in mitigating ocean acidification. By the year 2100, relative to RCP8.5, SRM causes a decrease in surface ocean hydrogen ion concentration ([H+]) by 6% and attenuates the seasonal amplitude of [H+] by about 10%. The simulations also show that SRM has a small effect on globally integrated ocean net primary productivity relative to the high-CO2 simulation without SRM. This study contributes to a comprehensive assessment of the effects of SRM on both the physical climate and the global carbon cycle.摘要太阳辐射干预地球工程是应对气候变化的备用应急措施. 其基本思路是通过减少到达大气和地表的太阳辐射, 从一定程度上抵消温室效应引起的全球变暖. 本研究使用地球系统模式模拟理想化太阳辐射干预方法对海洋碳循环的影响. 模拟试验中, 通过直接减少太阳辐射将RCP8.5 CO2排放情景下的全球平均温度降低到RCP4.5情景下的温度. 模拟结果表明, 到2100年, 相对于RCP8.5情景, 减少太阳辐射通过增加陆地碳汇, 使大气CO2浓度降低了65 ppm. 减少太阳辐射对海洋酸化影响很小. 到 2100 年, 相对于RCP8.5情景, 减少太阳辐射使海表平均氢离子浓度减少6%, pH上升0.03, 同时使海表平均氢离子浓度的季节变化振幅衰减约10%. 模拟结果还表明, 减少太阳辐射对全球海洋净初级生产力的影响较小. 本研究有助于深化我们对太阳辐射干预地球工程的气候和碳循环效应的认知和综合评估. 相似文献
Coral reefs are highly vulnerable to the impacts of rising marine temperatures and marine heatwaves. Mitigating dangerous climate change is essential and urgent, but many reef systems are already suffering on current levels of warming. Geoengineering options are worth exploring to protect the Great Barrier Reef (GBR) from extreme warming conditions, but we contend that they require strong governance and public consultation from the outset. Australian governments are currently funding feasibility testing of three geoengineering proposals for the GBR. Each proposal involves manipulating ocean or atmospheric conditions to lower water temperatures and thereby reduce the threat of mass coral bleaching events. Innovative strategies to protect the GBR and field testing of these is essential, but current laws do not guarantee robust governance for field testing of these technologies. Nor do they provide the foundation for a more coherent national policy on climate intervention technologies more generally. Responsible governance frameworks, including detailed risk assessment and early public consultation, are necessary for geoengineering research to build legitimacy and promote scientific progress.
Key policy insights
Marine heatwaves pose a serious threat to coral reefs, including Australia’s iconic Great Barrier Reef.
Australian governments have recognized the threats of warming waters, and are funding research of geoengineering options for the Great Barrier Reef.
The limited earlier field testing of geoengineering demonstrates the need for specific governance to manage risks, build legitimacy and maintain public support.
Australia requires a framework to govern geoengineering research and development before deployment of such technologies.
下载免费PDF全文