标题： 更新于2012年7月 | 食品危机：美国干旱 显示英文标题

标题： UPDATE July 2012 | The Food Crises: The US Drought

摘要： 近期美国中西部的干旱可能引发投机者助推的食物价格泡沫，从而导致全球性灾难。 在这里，我们使用经过验证的定量模型展示了投机者对食品价格的影响，该模型准确描述了历史食品价格。 在过去六年里，高且波动剧烈的食品价格导致了广泛的饥饿和社会动荡。 尽管在2012年春季食品价格出现了一次相对下降，但6月和7月美国中西部的大规模干旱威胁着触发另一场危机。 在之前的一篇论文中，我们构建了一个模型，其量化结果与食品价格相符，并证明虽然这种行为无法用供求经济学解释，但可以通过一个包含玉米转化为乙醇以及投机者趋势跟踪的模型来简洁而准确地描述。 2012年2月对该原始论文的更新表明，之前发表的模型预测了持续的价格动态，并预计如果未采取足够的政策行动，到2012年底将发生新的食品危机。 在这里，我们提供了第二个更新，评估当前干旱对全球食品价格的影响。 我们发现，干旱可能会提前触发预期中的第三次食品价格泡沫，这比限制投机的措施计划生效的时间更早。 减少用于转化为乙醇的玉米数量可能解决眼前的危机。 从长远来看，市场稳定需要限制金融投机。 显示英文摘要

摘要： Recent droughts in the midwestern United States threaten to cause global catastrophe driven by a speculator amplified food price bubble. Here we show the effect of speculators on food prices using a validated quantitative model that accurately describes historical food prices. During the last six years, high and fluctuating food prices have lead to widespread hunger and social unrest. While a relative dip in food prices occurred during the spring of 2012, a massive drought in the American Midwest in June and July threatens to trigger another crisis. In a previous paper, we constructed a model that quantitatively agreed with food prices and demonstrated that, while the behavior could not be explained by supply and demand economics, it could be parsimoniously and accurately described by a model which included both the conversion of corn into ethanol and speculator trend following. An update to the original paper in February 2012 demonstrated that the model previously published was predictive of the ongoing price dynamics, and anticipated a new food crisis by the end of 2012 if adequate policy actions were not implemented. Here we provide a second update, evaluating the effects of the current drought on global food prices. We find that the drought may trigger the expected third food price bubble to occur sooner, before new limits to speculation are scheduled to take effect. Reducing the amount of corn that is being converted to ethanol may address the immediate crisis. Over the longer term, market stabilization requires limiting financial speculation.