Robust features of future climate change impacts on sorghum yields in West Africa
Robust features of future climate change impacts on sorghum yields in West Africa
复制标题
未来气候变化对西非高粱产量影响的显着特征
DOI：
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发表时间：
2014
期刊：
影响因子：
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通讯作者：
D. Lobell
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作者：
B. Sultan;K. Guan;M. Kouressy;M. Biasutti;C. Piani;G. Hammer;G. McLean;D. Lobell
西非极易受到气候灾害的影响，迫切需要更好地量化和了解气候变化对作物产量的影响。本文评估了近期气候变化对西非高粱产量的影响，并考虑了未来气候情景和作物模型的不确定性。为了实现这一目标，我们利用9个修正偏倚的CMIP5气候模型和2个作物模型（SARRA-H和APSIM）的模拟来评估该地区预测作物产量影响的稳健性。与CMIP5整体大致一致，我们的偏差校正气候模式子集预测，与1961-1990年的基线相比，2031-2060年的几十年平均变暖+2.8°C，西非降雨量将出现强劲变化，萨赫勒西部（塞内加尔、马里西南部）降雨减少，萨赫勒中部（布基纳法索、尼日尔西南部）降雨增加。预测的降水不足集中在萨赫勒西部季风季节早期，而在整个萨赫勒季风季节后期发现正降水变化，表明季风季节性的转变。为了应对这种气候变化，但不考虑作物对二氧化碳的直接反应，萨赫勒西部地区的平均作物产量下降了约16-20%，年变率增加，而东部地区的影响要温和得多。萨赫勒西部和东部地区在气候和影响预测方面的这种差异在本研究中使用的气候和作物模型中是高度一致的。我们研究了不同品种选择、营养处理和作物对CO2响应的影响的稳健性。现代品种对平均产量和产量变异性的不利影响最小，因为它们的生长周期短且几乎固定，似乎更能适应季风的季节性变化，因此表明季节较短的品种可以被认为是对持续气候变化的潜在适应。通过增加肥料投入来缓解氮胁迫会增加绝对产量，但也会使作物对气候胁迫的响应更强，从而在相对意义上增强了气候变化的负面影响。最后，二氧化碳施肥将显著抵消气候对高粱产量的负面影响，抵消幅度约为10%，其中干旱地区受益最大，尽管考虑到二氧化碳的影响，气候变化的净影响仍然是负的。
West Africa is highly vulnerable to climate hazards and better quantification and understanding of the impact of climate change on crop yields are urgently needed. Here we provide an assessment of near-term climate change impacts on sorghum yields in West Africa and account for uncertainties both in future climate scenarios and in crop models. Towards this goal, we use simulations of nine bias-corrected CMIP5 climate models and two crop models (SARRA-H and APSIM) to evaluate the robustness of projected crop yield impacts in this area. In broad agreement with the full CMIP5 ensemble, our subset of bias-corrected climate models projects a mean warming of +2.8 °C in the decades of 2031–2060 compared to a baseline of 1961–1990 and a robust change in rainfall in West Africa with less rain in the Western part of the Sahel (Senegal, South-West Mali) and more rain in Central Sahel (Burkina Faso, South-West Niger). Projected rainfall deficits are concentrated in early monsoon season in the Western part of the Sahel while positive rainfall changes are found in late monsoon season all over the Sahel, suggesting a shift in the seasonality of the monsoon. In response to such climate change, but without accounting for direct crop responses to CO2, mean crop yield decreases by about 16–20% and year-to-year variability increases in the Western part of the Sahel, while the eastern domain sees much milder impacts. Such differences in climate and impacts projections between the Western and Eastern parts of the Sahel are highly consistent across the climate and crop models used in this study. We investigate the robustness of impacts for different choices of cultivars, nutrient treatments, and crop responses to CO2. Adverse impacts on mean yield and yield variability are lowest for modern cultivars, as their short and nearly fixed growth cycle appears to be more resilient to the seasonality shift of the monsoon, thus suggesting shorter season varieties could be considered a potential adaptation to ongoing climate changes. Easing nitrogen stress via increasing fertilizer inputs would increase absolute yields, but also make the crops more responsive to climate stresses, thus enhancing the negative impacts of climate change in a relative sense. Finally, CO2 fertilization would significantly offset the negative climate impacts on sorghum yields by about 10%, with drier regions experiencing the largest benefits, though the net impacts of climate change remain negative even after accounting for CO2.