USDA California Climate Hub, Davis, CA 95616, United States of America; John Muir Institute of the Environment, University of California, Davis, CA 95616, United States of America.
Division of Agriculture and Natural Resources, University of California, Merced, CA 95343, United States of America.
Sci Total Environ. 2021 Mar 25;762:143971. doi: 10.1016/j.scitotenv.2020.143971. Epub 2020 Dec 1.
Frost exposure is a particular challenge for cultivating perennial crops, whose adaptive capacity to weather and climate impacts is limited. Irrigation is a common means of mitigating damage, but draws on limited water resources, is costly, and energy intensive. Here we examined the projected impact of climate change on the incidence of frost temperatures during the coldest winters, defined by the 98th percentile of cool season (November-April) frost hours, under both early- and mid-21st century time periods, as compared to contemporary conditions, across a range of threshold temperatures. We focused on three high-value perennial orchard crops - almonds, avocados, and oranges - to assess the effects of climate change on the incidence of temperatures below crop-specific threshold temperatures and for crop-specific critical development phases, and what these temporal changes in frost exposure may mean for the water and energy requirements for mitigating damages. Across time periods and temperature thresholds, frost exposure declines in California's agricultural regions, with an average of reduction in frost exposure of 63% by the mid-21st century. The majority of almond and orange acreage saw 50-75% reductions in frost exposure by mid-century, while avocado acreage experienced >75% fewer frost hours. This yielded attendant reductions in water use and energy costs, and growers in the highest acreage counties may save more than 50,000 acre feet of water and $4.2 million in electricity costs for water pumping per year, collectively. Although climate change is projected to increase growing season crop water demands, pest pressures, and have an overall net-negative impact on agriculture, the potential reduction in frost exposure and the accompanying water and energy costs to mitigate frost damages may allow growers to reprioritize some of their long-term decisions around farm management.
霜害是栽培多年生作物的一个特殊挑战，其适应天气和气候影响的能力有限。灌溉是减轻损害的常用手段，但它依赖于有限的水资源，成本高，能源密集。在这里，我们研究了在 21 世纪早期和中期，与当代条件相比，在一系列阈值温度下，最寒冷冬季（11 月至 4 月）霜期 98%百分位的寒冷季节霜期发生率受气候变化影响的情况。我们重点关注三种高价值的多年生果园作物——杏仁、鳄梨和橙子——以评估气候变化对低于作物特定阈值温度的温度的发生率以及对作物特定关键发育阶段的影响，以及这些霜害时间变化对缓解损害的用水和能源需求意味着什么。在不同时期和温度阈值下，加利福尼亚农业区的霜害减少，到 21 世纪中期，霜害平均减少 63%。杏仁和橙子的大部分种植面积的霜害减少了 50-75%，而鳄梨的种植面积减少了>75%的霜期。这带来了用水量和能源成本的减少，种植面积最大的县的种植者每年可能节省超过 50000 英亩英尺的水和 420 万美元的用于抽水的电费。尽管气候变化预计会增加生长季节作物的需水量、害虫压力，并对农业产生整体净负面影响，但霜害减少的潜力以及缓解霜害所需的用水和能源成本可能使种植者重新考虑其长期的农场管理决策。
