IPCC Climate Change Data: CGCM1 A2a Model: 2020 Mean Temperature

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. For the A2
emissions scenario the main emphasis is on a strengthening of
regional and local culture, with a return to family values in
many regions. The A2 world consolidates into a series of roughly
continental economic regions, emphasizing local cultural roots.
In some regions, increased religious participation leads many to
reject a materialist path and to focus attention on contributing
to the local community. Elsewhere, the trend is towards ncreased
investment in education and science and growth in economic
productivity. Social and political structures diversify with
some regions moving towards stronger welfare systems and reduced
income inequality, while others move towards "lean"
government. Environmental concerns are relatively weak, although
some attention is paid to bringing local pollution under control
and maintaining local environmental amenities. The A2 world sees
more international tensions and less cooperation than in A1 or
B1. People, ideas and capital are less mobile so that technology
diffuses slowly. International disparities in productivity, and
hence income per capita, are maintained or increased. With the
emphasis on family and community life, fertility rates decline
only slowly, although they vary among regions. Hence, this
scenario family has high population growth (to 15 billion by
2100) with comparatively low incomes per capita relative to the
A1 andB1 worlds, at US$7,200 in 2050 and US$16,000 in
2100.Technological change is rapid in some regions and slow in
others as industry adjusts to local resource endowments,
culture, and education levels. Regions with abundant energy and
mineral resources evolve more resource intensive economies,
while those poor in resources place very high priority on
minimizing import dependence through technological innovation to
improve resource efficiency and make use of substitute inputs.
The fuel mix in different regions is determined primarily by
resource availability. And divisions among regions persist in
terms of their mix of technologies, with high-income but
resource-poor regions shifting toward advanced post fossil
technologies (renewables in regions of large land availability,
nuclear in densely populated, resource poor regions) and
low-income resource-rich regions generally relying on older
fossil technologies.With substantial food requirements,
agricultural productivity is one of the main focus areas for
innovation and RD efforts in this future. Initially high levels
of soil erosion and water pollution are eventually eased through
the local development of more sustainable high-yield
agriculture.Although attention is given to potential local and
regional environmental damage, it is not uniform across regions.
For example, sulfur and particulate emissions are reduced in
Asia due to impacts on human health and agricultural production
but increase in Africa as a result of the intensified
exploitation of coal and other mineral resources. The A2 world
sees high energy and carbon intensity, and correspondingly high
GHG emissions. Its CO2 emissions are the highest of all four
scenario families. Data are available for the following
periods: 1961-1990, 2010-2039; 2040-2069; and 2090-2099, mean
and monthly change fields.

弗拉托（Flato）等人于1999年阐述了加拿大全球耦合模式（Canadian Global Coupled Model，CGCM1）的首个版本及其控制气候态。该模式的大气分量本质上为麦克法兰（McFarlane）等人1992年描述的GCMII。这是一款采用波数32三角截断的谱模式，其地表网格分辨率约为3.7°×3.7°，共包含10个垂直层。其海洋分量基于地球物理流体动力学实验室（Geophysical Fluid Dynamics Laboratory，GFDL）的MOM1.1代码构建，分辨率约为1.8°×1.8°，包含29个垂直层。该模式采用从非耦合海洋与大气模式运行（时长分别为10年与4000年）中得到的热量与水通量调整方案，随后执行"自适应"流程：通过耦合模式积分14年对通量调整场进行修正。研究团队采用当代CO₂浓度开展了该耦合模式的多世纪控制模拟，用以评估耦合模式气候的稳定性，并将模拟气候态及其变率与观测结果进行对比。研究团队还开展了4组瞬态气候变化模拟集合，相关内容由博尔（Boer）等人于1999a、b版中阐述。其中3组模拟采用的有效温室气体强迫变化，既对应1850年至今的观测强迫变化，也包含此后以每年1%复利速率增长的CO₂强迫，直至2100年。研究还基于朗纳（Langner）与罗德（Rodhe）1991年提出的硫循环模型得到的气溶胶载荷，通过增加地表反照率（同里德（Reader）与博尔1999年的研究）纳入硫酸盐气溶胶的直接强迫效应。第四组模拟仅考虑温室气体强迫的影响。模式预测的气候变化显然直接依赖于温室气体（及气溶胶）强迫的设定，而这类设定目前尚未明确。上述强迫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"情景类似，采用标准情景便于将本模式的结果与全球其他建模团队的结果进行对比。下文将展示部分模拟的初步结果。CGCM1的气候敏感性约为3.5℃。针对A2排放情景，其核心导向为强化区域与本土文化，多数地区回归家庭价值观。A2世界整合为若干大致以大陆为界的经济区域，突出本土文化根源。部分地区宗教参与度提升，促使许多人摒弃物质主义发展路径，转而专注于服务本地社区；其他地区则呈现出加大教育与科研投入、提升经济生产力的趋势。社会与政治结构呈现多元化特征：部分地区建立更为完善的福利体系，缩小收入不平等差距；另一些地区则推行"精简型"政府。环境议题的受关注度相对较低，仅部分地区着力管控本地污染、维护本地环境福祉。相较于A1与B1情景，A2世界的国际紧张局势更为突出，国际合作更为匮乏。人员、思想与资本的流动性较低，导致技术扩散速度缓慢。国际间的生产力进而人均收入差距持续存在甚至进一步扩大。由于侧重家庭与社区生活，尽管各地区生育率存在差异，但整体下降速度缓慢，因此该情景家族的人口增长较快，至2100年将达到150亿；相较于A1与B1世界，其人均收入水平较低，2050年为7200美元，2100年为16000美元。部分地区技术变革迅速，部分地区则较为缓慢，产业需适配本地的资源禀赋、文化与教育水平。能源与矿产资源丰富的地区发展资源密集型经济；资源匮乏的地区则高度优先通过技术创新降低进口依赖，提升资源利用效率并开发替代投入品。不同地区的燃料结构主要由资源可获得性决定。地区间的技术结构分化持续存在：高收入但资源匮乏的地区转向先进的后化石燃料技术（土地充足地区发展可再生能源，人口稠密、资源匮乏地区发展核电）；低收入且资源丰富的地区则普遍依赖传统化石燃料技术。由于粮食需求庞大，农业生产力成为该未来场景下创新与研发（Research and Development，RD）的核心领域之一。起初较为严重的土壤侵蚀与水污染问题，最终将通过本地发展可持续高产农业得到缓解。尽管人们关注潜在的本地与区域环境破坏，但这种关注在各地区并不均衡。例如，亚洲由于健康与农业生产受到影响，硫与颗粒物排放有所减少；而非洲则因加大煤炭与其他矿产资源开发，排放有所增加。A2世界的能源与碳强度较高，相应的温室气体（Greenhouse Gas，GHG）排放也较高，其CO₂排放量在四个情景家族中位居最高。本数据集涵盖以下时段的平均场与月变化场：1961-1990年、2010-2039年、2040-2069年及2090-2099年。