The potential value of seasonal forecasts in a changing climate in southern Africa
The potential value of seasonal forecasts in a changing climate in southern Africa
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南部非洲气候变化中季节性预报的潜在价值
DOI：
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发表时间：
2014
期刊：
影响因子：
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通讯作者：
M. Werner
中科院分区：
文献类型：
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作者：
H. Winsemius;E. Dutra;F. Engelbrecht;E. A. V. Garderen;F. Wetterhall;F. Pappenberger;M. Werner
南部非洲的自给农业很容易受到极端天气条件的影响。雨养农业的产量在很大程度上取决于与降雨相关的因素，例如季节性降雨总量、雨季的异常开始和长度以及干旱发生的频率。反过来，牲畜可能会受到气候压力的严重影响，例如异常炎热的天气，影响状况、繁殖、对害虫和病原体的脆弱性，并最终影响发病率和死亡率。气候变化可能会影响极端天气条件的频率和严重程度，从而影响自给农业的成功。一项潜在有趣的适应措施包括及时预测和警告此类极端事件，并结合缓解措施，让农民为发生的事件做好准备。本文使用基于极端气候情景的几个区域气候模型降尺度的一组气候变化预测，研究了由于南部非洲以及更详细的林波波盆地的气候变化，未来极端事件的频率可能如何变化。此外，本文通过欧洲中期天气预报中心（ECMWF）季节性预报系统的季节性气象预报评估了这些指标的可预测性。重点是干旱期的频率以及以温度热指数表示的热应激条件的频率。在未来发生频率增加且具有可预测性的地区，季节性预测在未来将变得越来越重要，因为它们通常可以促成明智的决策以实施缓解措施。多模型气候预测表明，干旱期的频率不太可能大幅增加，而各模型之间有一个明确且一致的信号，表明到本世纪末，热应激条件的频率会增加。季节性预报系统的技能分析表明，鉴于这两个指标都可以熟练地预测 12 月至 2 月的季节（至少比雨季提前 2 个月），因此利用天气预报有可能适应这种变化。对于预测高于正常值和低于正常值的情况尤其如此。热应激条件的频率比干旱期的频率具有更好的可预测性。尽管结果对当地的最终用户来说是有希望的，但仅靠预测不足以确保采取适当的应对措施。必须为适当的措施提供足够的支持，并且必须以针对具体情况、易于理解的形式传达预测。
Subsistence farming in southern Africa is vulnerable to extreme weather conditions. The yield of rain-fed agriculture depends largely on rainfall-related factors such as total seasonal rainfall, anomalous onsets and lengths of the rainy season and the frequency of occurrence of dry spells. Livestock, in turn, may be seriously impacted by climatic stress with, for example, exceptionally hot days, affecting condition, reproduction, vulnerability to pests and pathogens and, ultimately, morbidity and mortality. Climate change may affect the frequency and severity of extreme weather conditions, impacting on the success of subsistence farming. A potentially interesting adaptation measure comprises the timely forecasting and warning of such extreme events, combined with mitigation measures that allow farmers to prepare for the event occurring. This paper investigates how the frequency of extreme events may change in the future due to climate change over southern Africa and, in more detail, the Limpopo Basin using a set of climate change projections from several regional climate model downscalings based on an extreme climate scenario. Furthermore, the paper assesses the predictability of these indicators by seasonal meteorological forecasts of the European Centre for Medium-Range Weather Forecasts (ECMWF) seasonal forecasting system. The focus is on the frequency of dry spells as well as the frequency of heat stress conditions expressed in the temperature heat index. In areas where their frequency of occurrence increases in the future and predictability is found, seasonal forecasts will gain importance in the future, as they can more often lead to informed decision-making to implement mitigation measures. The multi-model climate projections suggest that the frequency of dry spells is not likely to increase substantially, whereas there is a clear and coherent signal among the models of an increase in the frequency of heat stress conditions by the end of the century. The skill analysis of the seasonal forecast system demonstrates that there is a potential to adapt to this change by utilizing the weather forecasts, given that both indicators can be skilfully predicted for the December–February season, at least 2 months ahead of the wet season. This is particularly the case for predicting above-normal and below-normal conditions. The frequency of heat stress conditions shows better predictability than the frequency of dry spells. Although results are promising for end users on the ground, forecasts alone are insufficient to ensure appropriate response. Sufficient support for appropriate measures must be in place, and forecasts must be communicated in a context-specific, accessible and understandable format.