IPCC Climate Change Data: CGCM1 B2a Model: 2080 Precipitation

The first version of the Canadian Global Coupled Model, CGCM1, and its control climate are described by Flato et al. (1999). The atmospheric component of the model is essentially GCMII described by McFarlane et al. (1992). It is a spectral model with triangular truncation at wave number 32 (yielding a surface grid resolution of roughly 3.7 degrees x3.7 degrees ) and 10 vertical levels. The ocean component is based on the GFDL MOM1.1 code and has a resolution of approximately 1.8 degrees x1.8 degrees and 29 vertical levels. The model uses heat and water flux adjustments obtained from uncoupled ocean and atmosphere model runs (of 10 years and 4000 years duration respectively), followed by an `adaption' procedure in which the flux adjustment fields are modified by a 14 year integration of the coupled model. A multi-century control simulation with the coupled model has been performed using the present-day CO2 concentration to evaluate the stability of the coupled model's climate, and to compare the modelled climate and its variability to that observed. An ensemble of four transient climate change simulations has been performed and is described in Boer et al. (1999a; b). Three of these simulations use an effective greenhouse gas forcing change corresponding to that observed from 1850 to the present, and a forcing change corresponding to an increase of CO2 at a rate of 1% per year (compounded) thereafter until year 2100. The direct forcing effect of sulphate aerosols is also included by increasing the surface albedo (as in Reader and Boer, 1999) based on loadings from the sulphur cycle model of Langner and Rodhe (1991). The fourth simulation considers the effect of greenhouse gas forcing only. The change in climate predicted by a model clearly depends directly on this specification of greenhouse gas (and aerosol) forcing, and of course these are not well known. The prescription described above is similar to the IPCC "business as usual" scenario, and using a standard scenario allows the results of this model to be compared to those of other modelling groups around the world. Some initial results from these simulations are presented below. The climate sensitivity of CGCM1 is about 3.5 degrees C. From the IPCC website: The B2 world is one of increased concern for environmental and social sustainability. Education and welfare programs are widely pursued leading to reductions in mortality and, to a lesser extent, fertility. The population reaches about 10 billion people by 2100, consistent with both the United Nations and IIASA median projections. Income per capita grows at an intermediary rate to reach about US$12,000 by 2050. By 2100 the global economy might expand to reach some US$250 trillion. International income differences decrease, although not as rapidly as in scenarios of higher global convergence (A1, B1). Local inequity is reduced considerably through the development of stronger community support networks. Generally high educational levels promote both development and environmental protection. Indeed, environmental protection is one of the few remaining truly international priorities. However, strategies to address global environmental challenges are less successful than in B1, as governments have difficulty designing and implementing agreements that combine environmental protection with mutual economic benefits. The B2 storyline presents a particularly favorable climate for community initiative and social innovation, especially in view of high educational levels. Technological frontiers are pushed less than in A1 and B1 and innovations are also regionally more heterogeneous. Globally, investment in R& continues its current declining trend, and mechanisms for international diffusion of technology and know-how remain weaker than in scenarios A1 and B1 (but higher than in scenario A2). Some regions with rapid economic development and limited natural resources place particular emphasis on technology development and bilateral co-operation. Technical change is therefore uneven. The energy intensity of GDP declines at about one percent per year, in line with the average historical experience of the last two centuries. Land-use management becomes better integrated at the local level in the B2 world. Urban and transport infrastructure is a particular focus of community innovation, contributing to a low level of car dependence and less urban sprawl. An emphasis on food self-reliance contributes to a shift in dietary patterns towards local products, with reduced meat consumption in countries with high population densities. Energy systems differ from region to region, depending on the availability of natural resources. The need to use energy and other resources more efficiently spurs the development of less carbon-intensive technology in some regions. Environment policy cooperation at the regional level leads to success in the management of some transboundary environmental problems, such as acidification due to SO2, especially to sustain regional self-reliance in agricultural production. Regional cooperation also results in lower emissions of NOx and VOCs, reducing the incidence of elevated tropospheric ozone levels. Although globally the energy system remains predominantly hydrocarbon-based to 2100, there is a gradual transition away from the current share of fossil resources in world energy supply, with a corresponding reduction in carbon intensity. Data are available for the following periods: 1961-1990, 2010-2039; 2040-2069; and 2090-2099 Mean monthly and change fields.加拿大全球耦合模式（Canadian Global Coupled Model）的首个版本CGCM1及其控制气候由Flato等人（1999）进行了详述。该模式的大气分量本质上为McFarlane等人（1992）所描述的通用环流模式II（General Circulation Model II，GCMII）。它是一款在波数32处采用三角形截断的谱模式，地表网格分辨率约为3.7°×3.7°，并设有10个垂直层。该模式的海洋分量基于地球物理流体动力学实验室（Geophysical Fluid Dynamics Laboratory，GFDL）MOM1.1代码构建，分辨率约为1.8°×1.8°，并设有29个垂直层。其热通量与水通量调整参数取自非耦合海洋与大气模式的模拟运行——二者的模拟时长分别为10年与4000年，随后执行一项适配流程：通过耦合模式14年的积分运算对通量调整场进行修正。研究团队借助当前大气二氧化碳浓度设置，开展了一项持续多个世纪的耦合模式控制模拟实验，以评估耦合模式气候系统的稳定性，并将模拟得到的气候及其变率与观测结果进行对比。 研究团队还开展了一组共4组瞬态气候变化模拟实验，相关内容由Boer等人（1999a；b）进行了阐述。其中3组模拟采用了对应1850年至今观测到的有效温室气体强迫变化，以及后续以每年1%复合增长率递增的二氧化碳强迫变化，直至2100年。此外，研究还纳入了硫酸盐气溶胶的直接强迫效应：基于Langner与Rodhe（1991）的硫循环模型所得到的气溶胶负荷数据，通过提升地表反照率来实现（正如Reader与Boer，1999中所述）。第4组模拟仅考虑了温室气体强迫的影响。 模式预测的气候变化显然直接取决于温室气体（与气溶胶）强迫的设定方案，而此类设定目前尚未得到充分认知。上述设定方案与政府间气候变化专门委员会（Intergovernmental Panel on Climate Change，IPCC）的“照常营业”情景较为相似，采用标准情景可便于将本模式的结果与全球其他建模团队的成果进行对比。下文将展示部分来自上述模拟实验的初步结果。CGCM1的气候敏感度约为3.5℃。 源自IPCC官网的内容如下：B2情景下的世界，其民众对环境与社会可持续性的关注度不断提升。各国广泛推行教育与福利项目，以降低死亡率，并在较小程度上控制生育率。到2100年，全球人口将达到约100亿，这与联合国及国际应用系统分析研究所（International Institute for Applied Systems Analysis，IIASA）的中位预测结果相符。人均收入以中等增速增长，到2050年将达到约12000美元。到2100年，全球经济总量或将达到约250万亿美元。国际间的收入差距有所缩小，尽管其缩小速度不及全球趋同程度更高的情景（如A1、B1情景）。 通过构建更完善的社区支持网络，本地的不平等状况得到了显著缓解。较高的整体教育水平同时推动了经济发展与环境保护。事实上，环境保护已是少数几项真正具有全球意义的优先事项之一。然而，应对全球环境挑战的战略成效不及B1情景，这是因为各国政府难以设计并落实兼具环境保护与互利经济收益的国际协议。B2情景的叙事框架为社区倡议与社会创新提供了尤为有利的环境，考虑到其较高的教育水平更是如此。相较于A1与B1情景，B2情景下的技术前沿推进速度更慢，且创新成果在区域间的异质性更强。全球范围内，研发（Research and Development，R&D）投资延续了当前的下滑趋势，国际技术与知识传播机制也弱于A1与B1情景（但强于A2情景）。部分经济发展较快且自然资源有限的地区，尤为重视技术研发与双边合作，因此技术变革的分布并不均衡。GDP的能源强度以每年约1%的速率下降，这与过去两个世纪的平均历史经验相符。 在B2情景的世界中，土地利用管理在地方层面的整合度有所提升。城市与交通基础设施是社区创新的重点领域，这有助于降低民众对私家车的依赖程度，并缓解城市蔓延现象。强调粮食自给自足推动了饮食结构向本地产品转变，在人口密度较高的国家，肉类消费量有所减少。不同地区的能源系统存在差异，这取决于自然资源的禀赋状况。提高能源与其他资源利用效率的需求，推动部分地区开发了低碳排放技术。区域层面的环境政策合作，使得部分跨界环境问题的治理取得了成效，例如二氧化硫导致的酸雨问题，这尤其有助于维持区域的粮食生产自给能力。区域合作还降低了氮氧化物（NOₓ）与挥发性有机化合物（VOCs）的排放量，减少了对流层臭氧浓度超标事件的发生。尽管到2100年，全球能源系统仍将以碳氢化合物为主，但世界能源供应中化石资源的占比正逐步降低，与之对应的是能源碳排放强度的下降。 以下时段的相关数据均可获取：1961-1990年、2010-2039年、2040-2069年以及2090-2099年，数据包含月平均场与气候变化量场。