Farm performance and climate: Climate-adjusted productivity for broadacre cropping farms

Overview \r\n\r\n This study examines the effect of climate variability and climate change on the productivity of Australian cropping farms between 1977-78 and 2014-15. This study combines ABARES farm survey data with spatial climate data to estimate the effect of climate conditions (such as, rainfall and temperature) on cropping farm productivity. The study then presents climate-adjusted productivity estimates with the effects of climate removed. For comparison, similar results are generated for farm wheat yields using the same data sources and methods. \r\n\r\n Key Issues \r\n• After removing the effects of climate, a clearer picture of underlying trends in farm productivity emerges. A slowdown in productivity growth is apparent during the 1990s, with productivity growth of 2.1 per cent per year between 1977-78 and 1993-94, and just 0.2 per cent per year between 1993-94 and 2006-07. However, there is evidence of a significant rebound in climate-adjusted productivity since 2006-07, with annual growth of 1.5 per cent per year. \r\n• During the past 20 years, large changes in Australia's climate have been observed, including reductions in average winter rainfall in southern Australia and general increases in temperature. The recent changes in climate have had a significant negative effect on the productivity of Australian cropping farms, particularly in south-western Australia and south-eastern Australia. \r\n• Although climate conditions for cropping have declined overall, some regions have been relatively unaffected or even experienced slight improvements since 2000-01, including the coastal high-rainfall zones of southern Australia, and parts of northern New South Wales and Queensland. In general, larger negative effects have occurred in lower-rainfall inland parts of the cropping zone (given these areas are more sensitive to rainfall decline). \r\n• Strong growth in productivity since 2006-07 has helped the cropping industry to offset the decline in climate conditions. Further, the results suggest that these recent productivity improvements reflect adaptation to the changing climate. \r\n• The results suggest that farmers have adapted to the longer-term changes in climate by focusing on technologies and management practices that improve productivity during dry years. Anecdotal information suggests that farmers have made a variety of management practice changes-including adoption of conservation tillage-to better exploit summer soil moisture, as an adaptation to reduced winter rainfall. \r\n• There is also evidence of shifts in the location of cropping activity over time. Both ABARES and ABS data shows that the amount of cropping activity in higher-rainfall zones-such as south-western Victoria-has increased in recent decades. At the same time, there is evidence that cropping activity has decreased in some inland areas that have been heavily affected by the deteriorating climate. \r\n

## 研究概述

本研究考察了1977-78年度至2014-15年度间，气候变率与气候变化对澳大利亚作物农场生产力的影响。本研究将澳大利亚农业与资源经济科学局（ABARES）农场调查数据与空间气候数据相结合，以估算降雨、气温等气候条件对作物农场生产力的作用效果。随后，本研究给出了剔除气候影响后的气候校正生产力估算结果。为便于对比，本研究基于相同的数据源与方法，针对农场小麦单产生成了类似的分析结果。

## 核心议题

• 剔除气候影响后，农场生产力的潜在趋势图景更为清晰。20世纪90年代，生产力增长明显放缓：1977-78年度至1993-94年度间，生产力年增长率为2.1%；1993-94年度至2006-07年度间，年增长率仅为0.2%。但2006-07年度以来，气候校正后的生产力出现了显著反弹，年增长率达1.5%。
• 过去二十年间，澳大利亚气候发生了显著变化，包括澳大利亚南部冬季平均降雨量减少，以及全域气温普遍上升。近期的气候变化对澳大利亚作物农场的生产力造成了显著负面影响，尤其在澳大利亚西南部与东南部地区。
• 尽管作物种植的整体气候条件有所恶化，但2000-01年度以来，部分区域受影响相对较小，甚至出现了小幅改善，包括澳大利亚南部沿海高降雨带，以及新南威尔士州北部与昆士兰州的部分区域。总体而言，作物种植区的内陆低降雨区域受到的负面影响更为显著（因这些区域对降雨减少更为敏感）。
• 2006-07年度以来的生产力强劲增长，帮助作物种植业抵消了气候条件恶化带来的损失。此外，研究结果表明，近期的生产力提升反映了农业生产对气候变化的适应行为。
• 研究结果显示，农民已通过聚焦于提升干旱年份生产力的技术与管理实践，适应了气候变化的长期趋势。轶事性信息显示，农民已采取多种管理实践调整措施——包括采用保护性耕作技术——以更好地利用夏季土壤水分，以此应对冬季降雨量减少的挑战。
• 另有证据表明，作物种植活动的区位随时间发生了转移。澳大利亚农业与资源经济科学局（ABARES）与澳大利亚统计局（ABS）的数据均显示，近几十年来，维多利亚州西南部等较高降雨带的作物种植活动量有所上升。与此同时，部分受气候恶化严重影响的内陆地区，其作物种植活动出现了下降。