CONTEXT

To meet the nutritional and environmental needs of a growing population, dairy producers must increase milk production while minimizing the farm-gate environmental impact and adapting to the effects of climate change.

OBJECTIVE

Here we comprehensively assess the effects of climate change on the environmental performance and productivity of three typical US dairy farms, and evaluate the potential benefits of adaptation strategies and implementation of Beneficial Management Practices (BMPs) for mitigating these effects and the potential increases in environmental impact.

METHODS

Using the Integrated Farm System Model (IFSM), we predicted the productivity and environmental impact of these baseline farms under current emission scenarios and climate projections of 6 general circulation models (GCM), for high and low emission scenarios. We simulated farm-specific BMPs for current and future climate conditions for both unadapted and ‘adapted’ field cultivation plans, based on experiences from other climate locations. Finally, the IFSM predictions were compared to those of two other process-based models to test result robustness.

RESULTS AND CONCLUSIONS

We find that the environmental impact of the three northern US dairy farms (New York, Pennsylvania, and Wisconsin) generally increases by mid-century, if no mitigation measures are taken. Overall, feed production is maintained, as decreased corn grain yields are compensated by increased forage yields. Adoption of farm-specific Beneficial Management Practices can substantially reduce the GHG emissions and nutrient losses from dairy farms under current climate conditions and stabilize the environmental impact in future climate conditions, while maintaining farm productivity (milk and feed production). A comparison of three models corroborates the estimated reductions in methane and ammonia emissions associated with BMPs, as well as the relative trend in P-loss reduction.

SIGNIFICANCE

This study provides a holistic assessment of the impacts of climate change on dairy production systems focusing on both feed production and environmental impacts. It demonstrates the interest of BMPs to both reduce GHG emissions and contribute to more resilient farming systems in a changing climate.

中文翻译：

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在不断变化的气候中评估和减少美国北部乳制品生产系统对环境的影响

语境

为了满足不断增长的人口的营养和环境需求，乳制品生产商必须提高牛奶产量，同时最大程度地减少农场对环境的影响，并适应气候变化的影响。

客观的

在这里，我们全面评估了气候变化对美国三个典型奶牛场的环境绩效和生产力的影响，并评估了适应策略和实施有益管理实践（BMP）的潜在好处，以减轻这些影响以及对环境的潜在影响。

方法

使用综合农场系统模型（IFSM），我们在高排放和低排放情景下，根据当前排放情景和6种通用循环模式（GCM）的气候预测，预测了这些基准农场的生产力和环境影响。我们根据其他气候地点的经验，针对当前和将来的气候条件，针对未适应和“适应”的田间种植计划模拟了针对农场的BMP。最后，将IFSM预测与其他两个基于过程的模型的预测进行了比较，以测试结果的鲁棒性。

结果与结论

我们发现，如果不采取缓解措施，到本世纪中叶，美国北部三个奶牛场（纽约，宾夕法尼亚州和威斯康星州）对环境的影响通常会在本世纪中期增加。总体而言，饲料产量得以维持，因为降低的玉米谷物产量可以通过提高草料产量来弥补。在当前气候条件下，采用特定于农场的有益管理实践可以大大减少奶牛场的温室气体排放和营养损失，并在未来气候条件下稳定环境影响，同时保持农场的生产力（牛奶和饲料生产）。三种模型的比较证实了与BMP相关的甲烷和氨气排放量的估计减少量以及P损失减少量的相对趋势。

意义

这项研究对气候变化对乳制品生产系统的影响进行了全面评估，重点是饲料生产和环境影响。它证明了BMPs既有兴趣减少温室气体排放，又有助于在不断变化的气候中促进更具弹性的耕作制度。