Collaborative Research: Using a Hierarchy of Models to Constrain the Temperature Dependence of Climate Sensitivity

合作研究：使用模型层次结构来约束气候敏感性的温度依赖性

• 批准号: 1623218
• 负责人: Timothy Cronin
• 金额: $ 26.9万
• 依托单位: Massachusetts Institute of Technology
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-11-15 至 2019-10-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1623218&HistoricalAwards=false
• 关键词: Collaborative; Research; Using; Hierarchy; Models

Climate sensitivity is typically defined as the increase in global temperature that would result from a doubling of atmospheric carbon dioxide (CO2) starting from the pre-industrial level. Climate sensitivity is the most important factor in determining the risk posed by anthropogenic greenhouse gas emissions, and high values of sensitivity with severe consequences cannot be ruled out.Climate sensitivity is generally assumed to be constant over the range of climate states relevant to global warming, but this assumption may not hold if climate sensitivity is high or if greenhouse gas concentrations rise to a level equivalent to several CO2 doublings (possibly over several centuries). Recent work by the PIs and others suggests that climate sensitivity could increase with global temperature, and this increase could influence the risk of large warming. Work performed here uses a simplified climate model, the Community Atmosphere Model version 5 (CAM5) coupled to a slab mixed layer ocean, to examine the temperature dependence of climate sensitivity over one, two, and three CO2 doublings. The model is used to generate a perturbed physics ensemble (PPE), in which parameters controlling the behavior of cloud and convection (for example the fractional mass entrainment rate for convection) are perturbed as a means of varying the strength of climate feedbacks. Further work uses a cloud resolving model (the System for Atmospheric Modeling, or SAM) on an idealized domain to identify reasonable choices of parameter values. The work also considers the possibility that the parameter values themselves could change as climate warms, thereby yielding a temperature dependence in sensitivity. Additional work looks at climate sensitivity in greenhouse warming simulations from the Coupled Model Intercomparison Project version 5 (CMIP5), to determine if the simulations exhibit temperature dependent climate sensitivity.The work has broader impacts due to the substantial societal consequences by high climate sensitivity and the desirability of constraints on how much warming can result from anthropogenic emissions. Temperature-dependent sensitivity may also help to interpret proxy records of past warm climates and climate change, thus the work has scientific as well as societal broader impacts. In addition, the project supports a graduate student and a postdoctoral research associate, so that workforce development is ensured in this research area.

气候敏感性通常定义为全球温度的升高，这将是由于从工业前水平开始的大气二氧化碳（CO2）增加的一倍。 Climate sensitivity is the most important factor in determining the risk posed by anthropogenic greenhouse gas emissions, and high values of sensitivity with severe consequences cannot be ruled out.Climate sensitivity is generally assumed to be constant over the range of climate states relevant to global warming, but this assumption may not hold if climate sensitivity is high or if greenhouse gas concentrations rise to a level equivalent to several CO2 doublings (possibly over several几个世纪）。 PI和其他人最近的工作表明，气候敏感性可能随着全球温度而增加，这种增加可能会影响大量变暖的风险。 这里执行的工作使用简化的气候模型，社区大气模型版本5（CAM5）耦合到平板混合层海洋，以检查一，两和三个CO2加倍的气候灵敏度的温度依赖性。 该模型用于生成扰动的物理集合（PPE），其中控制云和对流行为的参数（例如，将对流的分数质量夹带率）被扰动，作为改变气候反馈的强度的一种手段。 进一步的工作使用理想化的域上使用云解析模型（用于大气建模的系统或SAM），以确定参数值的合理选择。 这项工作还考虑了参数值本身随着气候温暖而变化的可能性，从而产生了敏感性的温度依赖性。 其他工作着眼于温室变暖模拟中的气候敏感性，该模型比较项目版本5（CMIP5）确定模拟是否表现出依赖温度的气候敏感性。由于高气候敏感性和对约束的良好性产生的良好社会后果，这项工作具有更大的影响，从而产生了多大的热情热量。 与温度有关的灵敏度也可能有助于解释过去温暖的气候和气候变化的代理记录，因此该工作具有科学和社会的更广泛影响。 此外，该项目还支持研究生和博士后研究助理，以便在该研究领域确保劳动力发展。