IPCC Climate Change Data: HADCM3 A1F Model: 2080 Minimum Temperature

The recent experiments performed at the Hadley Centre have used the new Unified Model (Cullen, 1993). These experiments represent a large step forward in the way climate change is modelled by GCMs and raises new possibilities for scenario construction. This experiment has overcome some of the major difficulties that were associated with the previous generations of equilibrium (circa IPCC 1990) and cold-start transient (circa IPCC 1992) climate change experiments. HadCM2 has a spatial resolution of 2.5 degrees x 3.75 degrees (latitude by longitude) and the representation produces a grid box resolution of 96 x 73 grid cells. This produces a surface spatial resolution of about 417km x 278 km reducing to 295 x 278km at 45 degrees North and South (comparable to a spectral resolution of T42). The equilibrium climate sensitivity (DT2x) of HadCM2, that is the global-mean temperature response to a doubling of effective CO2 concentration, is approximately 2.5 degrees C, although, this quantity varies with the time-scale considered. This is somewhat lower than most other GCMs (IPCC, 1992). In order to undertake a 'warm-start' experiment it is necessary to perturb the model with a forcing from an early historical era, when the radiative forcing was relatively small compared to the present. The Hadley Centre started their experiments performed with HadCM2 with forcing from the middle industrial era, about 1860 Mitchell et al., 1995 and Johns et al., 1995. The greenhouse gas only integrations, HadCM2GG, used the combined forcing of all the greenhouse gases as an equivalent CO2 concentration. A further series of integrations, HadCM2GS, used the combined equivalent CO2 concentration plus the negative forcing from sulphate aerosols. The HadCM2GG integrations simulated the change in forcing of the climate system by greenhouse gases since the early industrial period (taken by HadCM2 to be 1860). The addition of the negative forcing effects of sulphate aerosols represents the direct radiative forcing due to anthropogenic sulphate aerosols by means of an increase in clear-sky surface albedo proportional to the local sulphate loading (refer to Mitchell et al., 1995 for details of this method). The indirect effects of aerosols were not simulated. The modelled control climate shows a negligible long term trend in surface air temperature over the first 400 years. The trend is about +0.04 degrees C per century, which is comparable to other such experiments. HadCM2CON represents an improvement over previous generations of GCMs that have been used at the Hadley Centre (Johns et al., 1995 and Airey et al., 1995). The experiments performed have simulated the observed climate system using estimated forcing perturbations since 1860. Johns et al., (1995) and Mitchell et al., (1995) have established that HadCM2's sensitivity is consistent with the real climate system. The agreement between the observed global-mean temperature record and that produced in these experiments is better for HadCM2GS than for HadCM2GG. This implies that HadCM2Gs has captured the observed signal of global-mean temperature changes better than HadCM2GG for the recent 100-year record. The climate sensitivity of HadCM2 is about 2.5 degrees C From the IPCC website: The A1 Family storyline is a case of rapid and successful economic development, in which regional averages of income per capita converge - current distinctions between poor and rich countries eventually dissolve. In this scenario family, demographic and economic trends are closely linked, as affluence is correlated with long life and small families (low mortality and low fertility). Global population grows to some nine billion by 2050 and declines to about seven billion by 2100. Average age increases, with the needs of retired people met mainly through their accumulated savings in private pension systems. The global economy expands at an average annual rate of about three percent to 2100. This is approximately the same as average global growth since 1850, although the conditions that lead to a global economic in productivity and per capita incomes are unparalleled in history. Income per capita reaches about US$21,000 by 2050. While the high average level of income per capita contributes to a great improvement in the overall health and social conditions of the majority of people, this world is not without its problems. In particular, many communities could face some of the problems of social exclusion encountered by the wealthiest countries in the 20th century and in many places income growth could come with increased pressure on the global commons. Energy and mineral resources are abundant in this scenario family because of rapid technical progress, which both reduce the resources need to produce a given level of output and increases the economically recoverable reserves. Final energy intensity (energy use per unit of GDP) decreases at an average annual rate of 1.3 percent. With the rapid increase in income, dietary patterns shift initially significantly towards increased consumption of meat and dairy products, but may decrease subsequently with increasing emphasis on health of an aging society. High incomes also translate into high car ownership, sprawling suburbanization and dense transport networks, nationally and internationally. Land prices increase faster than income per capita. These factors along with high wages result in a considerable intensification of agriculture. Three scenario groups are considered in A1 scenario family reflecting the uncertainty in development of energy sources and conversion technologies in this rapidly changing world. Near-term investment decisions may introduce long-term irreversibilities into the market, with lock-in to one technological configuration or another. The A1B scenario group is based on a balanced mix of energy sources and has an intermediate level of CO2 emissions, but depending on the energy sources developed, emissions in the variants cover a very wide range. In the fossil-fuel intensive scenario group A1FI, emissions approach those of the A2 scenarios; conversely in scenario group A1T with low labor productivity or of rapid progress in "post-fossil" energy technologies, emissions are intermediate between those of B1 and B2. These scenario variants have been introduced into the A1 storyline because of its "high growth with high tech" nature, where differences in alternative technology developments translate into large differences in future GHG emission levels Ecological resilience is assumed to be high in this storyline. Environmental amenities are viewed in a utilitarian way, based on their influence on the formal economy. The concept of environmental quality might change in thisstoryline from"conservation" of nature to active "management" - and marketing - of natural and environmental services. Data are available for the following periods: 1961-1990, 2010-2039; 2040-2069; and 2090-2099 Mean monthly and change fields.哈德利中心（Hadley Centre）近期开展的实验采用了全新的统一模式（Unified Model，Cullen, 1993）。此类实验为全球气候模式（General Circulation Models, GCMs）模拟气候变化的范式带来了重大突破，同时为情景构建开辟了全新可能。本次实验攻克了此前几代平衡态（大致对应政府间气候变化专门委员会1990年报告，Intergovernmental Panel on Climate Change, IPCC 1990）与冷启动瞬态（大致对应IPCC 1992年报告）气候变化实验所面临的核心难题。 HadCM2的空间分辨率为2.5°×3.75°（纬度×经度），其网格划分方案共包含96×73个网格单元。据此得到的地表空间分辨率约为417km×278km，在南北纬45°处缩减至295km×278km，其性能与谱分辨率T42相当。HadCM2的平衡气候敏感度（DT2x），即有效二氧化碳浓度翻倍后的全球平均温度响应，约为2.5℃，不过该数值会随所考量的时间尺度发生变化。该数值略低于多数其他全球气候模式（IPCC, 1992）。 若要开展“暖启动”实验，需以早期历史时期的辐射强迫（radiative forcing）数据对模式进行扰动——该时期的辐射强迫相较当前水平相对更低。哈德利中心在基于HadCM2开展的实验中，采用了约1860年工业革命中期的辐射强迫数据（Mitchell et al., 1995；Johns et al., 1995）。仅考虑温室气体的积分实验（HadCM2GG）将所有温室气体的总强迫等效为二氧化碳浓度进行计算。另一组积分实验（HadCM2GS）则在等效二氧化碳浓度的基础上，叠加了硫酸盐气溶胶（sulphate aerosols）产生的负辐射强迫。 HadCM2GG实验模拟了自工业革命早期（该实验设定为1860年）以来，温室气体对气候系统辐射强迫的变化。硫酸盐气溶胶负强迫的加入，代表了人为源硫酸盐气溶胶通过晴空地表反照率（albedo）的提升产生的直接辐射强迫——反照率增幅与局地硫酸盐负荷呈正比（具体方法细节参见Mitchell et al., 1995）。实验未模拟气溶胶的间接气候效应。 模式控制气候的模拟结果显示，前400年地表气温的长期趋势可忽略不计，百年升温速率约为0.04℃，与同类实验的结果相当。HadCM2CON相较于哈德利中心此前使用的几代全球气候模式均有改进（Johns et al., 1995；Airey et al., 1995）。本次实验基于1860年以来的估算强迫扰动，对观测到的气候系统进行了模拟。Johns等人（1995）与Mitchell等人（1995）已证实，HadCM2的气候敏感度与真实气候系统相符。 相较于HadCM2GG实验，HadCM2GS实验的模拟结果与观测到的全球平均温度记录吻合度更高。这意味着在近百年的温度记录中，HadCM2GS相较HadCM2GG更准确地捕捉到了全球平均温度变化的观测信号。HadCM2的气候敏感度约为2.5℃。 数据源自政府间气候变化专门委员会官网： A1情景族假设经济发展快速且成效显著，区域人均收入水平将趋同——当前穷国与富国之间的收入差距最终将消失。在此情景族中，人口与经济趋势紧密绑定：富裕程度与高预期寿命、小家庭模式（低死亡率与低生育率）呈正相关。全球人口将在2050年增长至约90亿，到2100年回落至约70亿。人口平均年龄持续上升，退休群体的养老需求主要通过个人养老金账户的累积储蓄得到满足。 到2100年，全球经济将以约3%的年均增速扩张，这一水平与1850年以来的全球平均增速大致相当，不过推动全球生产力与人均收入增长的条件在历史上尚无先例。到2050年，人均收入将达到约21000美元。尽管较高的人均收入平均水平能够大幅改善多数人群的健康与社会福祉，但该情景下的世界仍存在诸多问题。具体而言，诸多社区可能面临20世纪富国曾遭遇的社会排斥问题，同时在诸多地区，收入增长会伴随全球公共资源承载压力的加剧。 该情景族中，由于技术进步快速，能源与矿产资源储量充足——技术进步既降低了单位产出的资源消耗，又提升了经济可开采储量。最终能源强度（单位GDP能耗）将以年均1.3%的速率下降。随着收入快速增长，饮食结构最初会显著向肉类与乳制品消费倾斜，但随着老龄化社会对健康关注度的提升，此类消费后续可能出现回落。高收入也会带来高汽车保有量、大规模郊区化以及国内国际密集的交通网络。土地价格的上涨速度快于人均收入。上述因素与高薪资共同推动了农业的大幅集约化发展。 A1情景族下设三个情景群组，用以反映快速变革的世界中，能源与能源转换技术发展路径的不确定性。短期投资决策可能会给市场带来长期不可逆性，进而锁定某一种或另一种技术路径。A1B情景群组以能源源的均衡混合为基础，二氧化碳排放水平处于中等区间；不过根据所采用的能源技术路径不同，各子情景的排放量跨度极大。在化石燃料密集型情景群组A1FI中，排放量接近A2情景的水平；相反，在劳动生产率较低或“后化石”能源技术快速进步的A1T情景群组中，排放量处于B1与B2情景之间。 由于A1情景族具有“高增长、高技术”的特征，不同技术发展路径的差异会导致未来温室气体排放水平的巨大差异，因此设置了上述情景子群组。该情景族假设生态系统韧性较高。环境福祉将以功利主义视角进行评估，即基于其对正规经济的影响。在此情景下，环境质量的概念可能会从“保护自然”转变为对自然与环境服务的主动“管理”乃至“市场化运营”。 可用数据涵盖以下时段：1961-1990年、2010-2039年、2040-2069年以及2090-2099年的逐月平均与变化量场数据。