The Influence of Climate Change on Winter Wheat during 2012-2100 under A2 and A1B Scenarios in China

By assuming constant winter wheat varieties and agricultural practices in China, the influence of climate change on winter wheat is simulated using the corrected future climate projections under SRES A2 and A1B scenarios from 2012 to 2100, respectively. The results indicate that the growth of winter wheat would be strongly influenced by climate change in future. The average flowering and maturity dates of winter wheat would advance by 26 and 27 days under scenario A2, and by 23 and 24 days respectively under scenario A1B from 2012 to 2100. The simulated potential productivity of winter wheat shows a decrease of 14.3% and 12.5% for scenarios A2 and A1B respectively without the fertilization effect of CO2, while an increase of 1.3% and 0.6% with the fertilization effect of CO2. Additionally, for northern China, the simulated potential productivity would markedly decrease under both scenarios, independent with the fertilization effect of CO2, which indicates that the current planted winter wheat would be more vulnerable than that in southern China. The most likely reason is the current winter wheat varieties in northern China are winter varieties or strong winter varieties, which need some days of low temperature for dormancy. While in southern China, the winter wheat is spring or half winter varieties and can grow slowly during winter, thus, they would be affected slightly when winter temperature increases. The results of this study may have important implications for adaptation measures.

Changes of Atmospheric Water Balance over China under the IPCC SRES A1B Scenario Based on RegCM3 Simulations

Simulations of the Regional Climate Model Version 3 (RegCM3) under the Intergovernmental Panel on Climate Change (IPCC) Special Report on Emissions Scenarios (SRES) A1B scenario were employed to investigate possible decadal changes and long-term trends of annual mean atmospheric water balance components over China in the 21st century with reference to the period of 1981-2000. An evaluation showed that RegCM3 can reasonably reproduce annual evapotranspiration, precipitation, and water vapor transport over China, with a better performance for March-June. It was found that the water vapor exchange between the land surface and atmosphere would be significantly intensified in Northwest China by the mid-to late-21st century and that the region would possibly shift to a wetter or drought-mitigated state under global warming. Conversely, the water vapor exchange evidently weakened over the Tibetan Plateau and South-west China by the mid-to late-21st century. In addition, there appears to be a drier state for Northeast China and the middle and lower reaches of the Yangtze River valley by the mid-to late-21st century, with slight mitigation by the end compared with the mid-21st century. The westerly and southwesterly water vapor transport over China generally presents an increasing trend, with increasing diver-gence over the Tibetan Plateau and Northeast China, corresponding to a loss of atmospheric water vapor by water vapor transport.

A1B情景下黄河源区径流变化趋势

采用SWAT模型和RegCM3模式预测A1B情景下黄河源区未来的径流变化趋势。构建了黄河源区SWAT模型,采用2000—2005年和2006—2008年逐日气温、降水、流量等实测水文气象数据对模型进行率定和验证,率定期纳西效率系数为0.86、相关系数为0.83,验证期纳西效率系数为0.89、相关系数为0.86,模拟效果好。评价RegCM3模式对黄河源区气温和降水的模拟能力,结果表明该模式对气温和降水的模拟具有很好的相关性,模拟效果令人满意。采用RegCM3模式预测的A1B情景下未来气候信息经系统校正和插值处理后,驱动所构建的SWAT模型模拟了黄河源区2010—2098年的径流系列,预估了黄河源区未来的径流变化趋势。研究结果表明,黄河源区唐乃亥水文站径流系列在2010—2098年总体上呈减少趋势,在2010—2039年、2040—2069年和2070—2098年3个时期呈减—增—减的交替变化趋势,其中2010—2039年和2040—2069年变化趋势不显著,2070—2098年呈显著减少趋势。

Prediction of Climate Change in Yangtze-Huaihe Region under the Background of Global Warming

Based on the prediction results of over twenty new climate models provided by Intergovernmental Panel on Climate Change(IPCC) ,the climate change trends in Yangtze-Huaihe region during 2011-2100 were analyzed under the SRES A1B scenario. The results showed that annual mean temperature in Yangtze-Huaihe region would go up gradually under the background of global warming,and temperature increase rose from southeast to northwest,while annual average temperature would increase by 3.3 ℃ in the late 20th century. Meanwhile,annual average precipitation would rise persistently,and precipitation increase would go up with the increase of latitude and the lapse of time,being obviously strengthened after 2041.

Contribution of Drought to Potential Crop Yield Reduction in a Wheat-Maize Rotation Region in the North China Plain

With consecutive occurrences of drought disasters in China in recent years, it is important to estimate their potential impacts on regional crop production. In this study, we detect the impacts of drought on wheat and maize yield and their changes at a 0.5＆#176;＆#215;0.5＆#176; grid scale in the wheat-maize rotation planting area in the North China Plain under the A1B climate change scenario using the Decision Support System for Agrotechnology Transfer （DSSAT） model and the outputs of the regional climate modeling system-Providing Regional Climates for Impacts Studies （PRECIS）. Self-calibrating palmer drought severity index was used as drought recognition indicator. Two time slices used for the study were the baseline （1961-1990） and 40 years of 2011-2050. The results indicate that the potential planting region for double crop system of wheat-maize would expend northward. The statistic conclusions of crop simulations varied considerably between wheat and maize. In disaster-affected seasons, wheat yield would increase in the future compared with baseline yields, whereas in opposite for maize yield. Potential crop yield reductions caused by drought would be lower for wheat and higher for maize, with a similar trend found for the ratio of potential crop yield reductions for both crops. It appears that the negative impact of drought on maize was larger than that on wheat under climate change A1B scenario.