IPCC Climate Change Data: CGCM1 A2a Model: 2020 Maximum 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.

Flato等人（1999年）对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进行了阐述。该模式的大气分量模块本质上采用了McFarlane等人（1992年）提出的GCMII（大气环流模式第二版），为谱模式，采用波数32的三角截断，其地表网格分辨率约为3.7°×3.7°，垂直方向共设10层。海洋分量模块基于GFDL MOM1.1代码构建，分辨率约为1.8°×1.8°，垂直方向共设29层。该模式采用从非耦合海洋与大气模式积分结果（分别时长10年与4000年）中获取的热通量与水通量调整方案，随后执行‘自适应’流程：通过耦合模式14年的积分过程对通量调整场进行修正。研究团队采用当前二氧化碳浓度开展了耦合模式的多世纪控制模拟试验，用以评估耦合模式气候态的稳定性，并将模式模拟的气候态及其变率与观测结果进行对比。

Boer等人（1999a；1999b）阐述了所开展的4组瞬变气候变化模拟集合试验。其中3组模拟采用了与1850年至今实际观测一致的有效温室气体强迫变化，以及此后以每年1%（复利增长）的速率递增的二氧化碳强迫变化，直至2100年。同时，基于Langner与Rodhe（1991年）提出的硫循环模型所得的硫酸盐气溶胶负荷，通过增加地表反照率（与Reader和Boer，1999年的方法一致），纳入了硫酸盐气溶胶的直接强迫效应。第4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取决于温室气体（及气溶胶）强迫的设定方案，而这类方案的不确定性目前仍较高。上述设定方案与IPCC（政府间气候变化专门委员会）的"business as usual"情景类似，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结果进行对比。下文将展示上述模拟试验的部分初步结果。CGCM1的气候敏感度约为3.5℃。

在A2排放情景下，核心导向为强化区域与本土文化，诸多地区回归家庭价值观。A2情景下的全球格局将整合为若干大致以大陆为界的经济区域，强调本土文化根源。部分地区宗教参与度的提升促使诸多群体摒弃物质主义路径，转而专注于为本地社区做贡献。其他地区则呈现出加大教育与科研投入、提升经济生产力的发展趋势。社会与政治结构呈现多元化特征：部分地区建立更完善的福利体系，降低收入不平等程度；而另一些地区则推行"lean"政府治理模式。公众对环境问题的关注度相对较低，尽管部分地区会关注本地污染治理与本地环境宜居性的维护。A2情景下的全球格局相较于A1与B1情景，面临更多国际紧张局势与更少的国际合作。人员、思想与资本的流动性更低，导致技术传播速度缓慢。各国之间的生产力差距进而人均收入差距得以维持甚至扩大。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），人均收入相较于A1与B1情景较低：2050年人均收入为7200美元，2100年为16000美元。

部分地区技术变革速度较快，而另一些地区则较为缓慢，这是因为各地区产业需适配本地的资源禀赋、文化与教育水平。拥有丰富能源与矿产资源的地区将发展资源密集型经济，而资源匮乏的地区则将通过技术创新提升资源利用效率、开发替代投入品，以此最大限度降低对进口的依赖作为首要任务。不同地区的能源结构主要由资源可得性决定。各地区的技术结构分化依然存在：高收入但资源匮乏的地区将转向先进的后化石能源技术（土地资源丰富的地区采用可再生能源，人口密集、资源匮乏的地区采用核能）；而低收入且资源丰富的地区则普遍依赖较为传统的化石能源技术。

由于存在大量的粮食需求，农业生产力是该未来情景下创新与研发（Research and Development，RD）工作的核心方向之一。最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更可持续的高产农业得到缓解。尽管人们关注本地与区域潜在的环境破坏问题，但各地区的重视程度并不一致。例如，由于考虑到对人类健康与农业生产的影响，亚洲地区的硫氧化物与颗粒物排放有所减少；而非洲地区则因加大煤炭与其他矿产资源的开发力度，排放出现增长。A2情景下的全球格局呈现较高的能源强度与碳强度，相应的温室气体（Greenhouse Gas，GHG）排放量也较高，其二氧化碳排放量是四类情景家族中最高的。

本数据集包含以下时段的平均与逐月变化场数据：1961-1990年、2010-2039年、2040-2069年以及2090-2099年。