Monitoring and predicting the effects of climate change on crop yields

气候变化是英国和全球未来粮食生产面临的最大风险之一。英国约有72%（1750万公顷）的土地被耕种，其中37%是生产性耕地。2017年，英国农业部门直接雇用了419，000人，每年产生103亿英镑的总增加值。普遍的共识是，气候变化将对英国农业产生重大的积极和消极影响，这些影响将因地理区域而异。与气候有关的影响可能通过逐渐的长期变化发生，也可能是干旱和多雨冬季等极端天气事件引发的更迅速和随机变化的结果。在中短期内，我们预计玉米等某些作物的生长将受益于更长的生长季节和更高的温度。然而，从长远来看，降雨模式的变化、蒸发量的增加和可用水量的减少都将威胁到作物生产。同样，日益潮湿的秋季将限制农业生产，对耕作时间产生不利影响。这可能间接造成环境破坏，如土壤压实和侵蚀。然而，这些影响的位置和严重程度以及扰动后的恢复速度仍有很大的不确定性。将气候变化对作物生产的影响与影响产量的许多其他技术和社会经济因素分开，仍然是研究的一个主要挑战。这种不确定性和知识的缺乏使英国农业部门对未来不断变化的气候准备不足。2018年夏季干旱对许多主要作物产量的重大影响就表明了这一点。BBSRC和NERC目前正在资助一个大型的国家能力研究方案“实现可持续农业系统，ASSIST”（https：//assist.ceh.ac.uk/），并得到农业的大力支持。作为该计划的一部分，生态与水文中心组建了一支强大的多学科和跨学科团队，以开发和测试新的农业系统。在ASSIST的基础上，CROP-NET项目旨在为英国提供强大的实时作物和牧草产量监测和建模服务，以改进对未来气候变化影响的预测。具体而言，我们将探讨：1）使用地球观测数据结合农业收集的大量精确产量数据的可行性，以提供对英国各地作物产量的气候相关风险的早期预警检测;2）根据UKCP 18使用英国气候的精细规模预测，以代表未来30-40年气候变化情景的全方位英国各地的目标位置。这一过程将考虑可能影响作物生长和产量的不同时间分辨率（例如夏季平均温度、干旱期和热峰）下的不同气候变量（例如温度、降水）。通过这种方式，对产量的监测将提供数据，以区分气候变化影响产量的不同过程;3）影响农民对气候变化威胁的看法的关键社会和经济因素，以及他们调整农业系统以应对气候变化的意愿和能力;以及4）利用来自已建立的实时作物产量监测网络的数据来提高作物生长模型的预测能力以建立示范预测服务的可行性，从而为作物生产的气候适应战略提供信息。

Climate change poses one of the greatest risks to future food production both in the UK and globally. Around 72% (17.5 million hectares) of the UK land area is farmed, with 37% of this as productive arable land. In 2017, the UK agriculture sector employed 419,000 people directly and generated Gross Value Added of £10.3 billion each year. The general consensus is that climate change will have both significant positive and negative impacts on UK agriculture, and these will vary depending on geographic region. Climate-related impacts may occur through gradual, long-term change, or as a result of more rapid and stochastic changes triggered by extreme weather events, such as droughts and wet winters. In the short- to medium-term, we expect the growth of certain crops, such as maize, to benefit from longer growing seasons and higher temperatures. However, in the longer-term, changing patterns of rainfall, increased evaporation and reduced water availability will all threaten crop production. Similarly, increasingly wet autumns will constrain agricultural production by adversely affecting the timing of farming operations. These could indirectly result in environmental damage, such as soil compaction and erosion. However, considerable uncertainty remains as to the location and severity of these impacts, and the rate of recovery following perturbations. It remains a research major challenge to disaggregate the impacts of climate change on crop production from many other technological and socio-economic factors affecting yield. This uncertainty and a lack of knowledge have left the UK agricultural sector poorly prepared for a future, changing climate. An indication of this was provided by the significant impact of the 2018 summer drought on yields of many major crops. BBSRC and NERC are currently funding a large national capability research programme "Achieving Sustainable Agricultural Systems, ASSIST" (https://assist.ceh.ac.uk/), with strong support from the farming industry. As part of this programme, the Centre for Ecology & Hydrology has assembled a strong multi- and inter-disciplinary team to develop and test new farming systems. Building on ASSIST, the CROP-NET project aims to scope out the requirements for a robust, real-time crop and grass yield monitoring and modelling service for the UK to provide improved predictions of future climate change impacts. Specifically, we will explore:1) the feasibility of using Earth Observation data in combination with large volumes of precision yield data collected by the farming industry to provide early warning detection of climate-related risks to crop yields across the UK;2) the use of fine-scale projections of UK climate under UKCP18 to target locations across the UK that represent the full range of climate change scenarios over the next 30-40 years. This process will consider different climate variables (e.g. temperature, precipitation) at different temporal resolutions (e.g. average summer temperature, drought periods, and heat peaks) that are likely to affect crop growth and yield. In this way, the monitoring of yield will provide data to pick apart the different process by which climate change will affect yields;3) the key social and economic factors affecting farmer perception of climate change threats, and their willingness and ability to adapt their farming systems in response to this; and4) the viability of using data from an established, real-time crop yield monitoring network to improve the predictive power of crop growth models to build a demonstrator prediction service, and therefore inform climate adaptation strategies for crop production.