Monitoring and predicting the effects of climate change on crop yields

气候变化是英国乃至全球未来粮食生产面临的最大风险之一。英国约72%(1750万公顷)的土地被耕种，其中37%是生产性耕地。2017年，英国农业直接就业41.9万人，每年创造103亿GB的增加值。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是通过渐进的、长期的变化发生的，也可能是由干旱和潮湿的冬季等极端天气事件引发的更迅速和更随机的变化的结果。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和更高的气温。然而，从长远来看，降雨模式的改变、蒸发量的增加和可用水的减少都将威胁到作物产量。同样，越来越潮湿的秋季将对农业作业的时机产生不利影响，从而限制农业生产。这些都可能间接导致环境破坏，如土壤压实和侵蚀。然而，关于这些影响的位置和严重程度，以及在扰动后的恢复速度，仍然存在相当大的不确定性。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，仍然是研究的主要挑战。这种不确定性和知识的缺乏让英国农业部门对未来气候变化的准备不足。2018年夏季干旱对许多主要农作物的产量产生了重大影响，这表明了这一点。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，协助”(https://assist.ceh.ac.uk/)，)，并得到农业的大力支持。作为这一方案的一部分，生态和水文学中心组建了一个强大的多学科和跨学科团队来开发和测试新的耕作系统。作物网项目以ASSIST为基础，旨在为英国提供强大的、实时的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。具体地说，我们将探索：1)将地球观测数据与农业收集的大量精确产量数据相结合，为英国各地的作物产量提供气候相关风险的早期预警检测；2)根据UKCP18使用英国气候精细预测，以英国各地代表未来30-40年气候变化情景的地点为目标。这一过程将考虑不同时间分辨率下的不同气候变量(例如温度、降水)(例如夏季平均温度、干旱时期和热峰)，这些变量可能会影响作物的生长和产量。通过这种方式，产量监测将提供数据，以区分气候变化将影响产量的不同过程；3)影响农民对气候变化威胁的感知的关键社会和经济因素，以及他们适应气候变化的意愿和能力；4)利用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的可行性，以建立示范预测服务，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.