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.

气候敏感性通常被定义为大气中的二氧化碳（CO2）从工业化前水平开始增加一倍所导致的全球温度升高。 气候敏感性是确定人为温室气体排放造成的风险的最重要因素，不能排除高敏感性值带来严重后果的可能性。气候敏感性通常被假定为在与全球变暖相关的气候状态范围内保持不变，但如果气候敏感性很高，或者温室气体浓度上升到相当于几个二氧化碳当量的水平，（可能超过几个世纪）。 PI和其他人最近的工作表明，气候敏感性可能会随着全球气温的升高而增加，这种增加可能会影响大规模变暖的风险。 在这里进行的工作使用一个简化的气候模式，社区大气模式版本5（CAM 5）耦合到一个板混合层海洋，研究气候敏感性的温度依赖性超过一个，两个，和三个CO2 double。 该模式被用来生成扰动物理系综（PPE），其中控制云和对流的行为（例如对流的分数质量夹带率）的参数被扰动，作为改变气候反馈强度的一种手段。 进一步的工作使用云解析模型（大气建模系统，或SAM）在一个理想化的域，以确定合理的选择参数值。 这项工作还考虑了参数值本身可能随着气候变暖而变化的可能性，从而产生灵敏度的温度依赖性。 其他工作着眼于气候敏感性在温室效应模拟从耦合模式相互比较项目版本5（CMIP 5），以确定是否模拟表现出温度依赖的气候敏感性。这项工作具有更广泛的影响，由于重大的社会后果的高气候敏感性和可取的限制多少变暖可以导致人为排放。 温度敏感性也可能有助于解释过去温暖气候和气候变化的代用记录，因此这项工作具有科学和更广泛的社会影响。 此外，该项目还支持一名研究生和一名博士后研究助理，以确保该研究领域的劳动力发展。