Projected changes in annual mean temperature (°C) under RCP 4.5 for the 2080-2099 time period based on the Max Planck Institute Coupled Earth System Model (MPI-ESM-LR)

The analyses of future climate change over South Africa as described in the Third National Communication, are from the projections of the Coupled Global Climate Models (CGCMs) of the Coupled Model Intercomparison Project Phase 5 (CMIP5) and Assessment Report (AR) 5 of the Intergovernmental Panel on Climate Change (IPCC). These projections are used to inform on the uncertainty range of the large-scale climate change futures over the southern African region. At the Council for Scientific Industrial Research (CSIR), a dynamic regional climate model CCAM (conformal-cubic atmospheric model) of the Commonwealth Scientific and Industrial Research Organisation (CSIRO) was used to downscale CMIP5 CGCM projections to 50 km resolution over Africa. These downscalings were for both Representative Concentration Pathway (RCP) 8.5 and Representative Concentration Pathway (RCP) 4.5 of AR5 of the IPCC. RCP 4.5 describes a future with relatively ambitious emission reductions whereas RCP 8.5 describes a future with no reductions in emissions. Emissions in RCP 4.5 peak around 2040, then decline and in RCP 8.5 emissions continue to rise throughout the 21st century. The change in temperature is expressed as an anomaly, the difference between the average climate over a period of the last several decades (1971-2000), and the projected climate (short to medium term 2021 to 2050). The simulations were performed on supercomputers of the CSIRO and on the Centre for High Performance Computing (CHPC) of the Meraka Institute of the CSIR in South Africa.

如《第三次国家通讯》所述，南非未来气候变化分析的数据来源于耦合模式比较计划第五阶段（Coupled Model Intercomparison Project Phase 5, CMIP5）的耦合全球气候模型（Coupled Global Climate Models, CGCMs）以及政府间气候变化专门委员会（Intergovernmental Panel on Climate Change, IPCC）的第五次评估报告（Assessment Report 5, AR5）。这些预测结果用于揭示南部非洲区域未来大规模气候变化的不确定性范围。南非科学与工业研究理事会（Council for Scientific Industrial Research, CSIR）采用澳大利亚联邦科学与工业研究组织（Commonwealth Scientific and Industrial Research Organisation, CSIRO）研发的 conformal-cubic 大气模型（conformal-cubic atmospheric model, CCAM），将CMIP5耦合全球气候模型的预测结果降尺度至非洲区域50公里分辨率。此次降尺度针对IPCC第五次评估报告中的两种典型浓度路径（Representative Concentration Pathway, RCP）情景展开：RCP 4.5描述了一个减排目标相对积极的未来情景（排放量于2040年左右达到峰值后逐渐下降），而RCP 8.5则对应无减排措施的情景（排放量在整个21世纪持续上升）。温度变化以异常值表示，即过去数十年（1971-2000年）平均气候与未来中短期（2021-2050年）预测气候之间的差值。相关模拟计算在CSIRO的超级计算机以及南非CSIR Meraka研究所的高性能计算中心（Centre for High Performance Computing, CHPC）上完成。