SusCrop - Developing resilience and tolerance of crop resource use efficiency to climate change and air pollution

Climate change will impact arable crop production in coming decades and air pollution is already having substantial impacts on crop productivity causing significant yield losses across Europe. In spite of international efforts to reduce emissions, poor air quality in Europe is currently set to continue until at least 2050 and GHG emissions are still on course to see large changes in climate over the coming decades. In the SUSCAP project, we investigated how these stresses will combine to impact crop growth, development and yield through influences on important crop resource use efficiencies such as radiation, water and nutrient use. We developed a new generation of process-based crop models to better understand the mechanisms, and hence impacts, of these multiple stresses both for the current-day and future 2050 climates. This allows us to identify the magnitude, frequency and geographical distribution of the combined stresses most likely to limit resource use efficiency and hence crop productivity. Experiments performed in open top chambers in central Spain during 2020 found that high ozone concentrations caused decreased photosynthesis and subsequent yield losses of ~17%. Water stress was found to limit the effect of ozone damage, but both high ozone and drought in combination resulted in increased yield losses of ~30% more than for the two individual stresses. The results of these experiments have been used to calibrate and evaluate the new generations of crop models, along with remote sensing data and results from the AgMIP-ozone crop modelling initiative. The improved accuracy of the crop models means that we are now capable of assessing the combined effects of pollution and climate stress on crop development, growth and yield in European climates, both for the present and the future. A regional chemical transport model (WRF-Chem) was set up using anthropogenic fire emissions, meteorological input data and boundary conditions, and was optimized by running test simulations of aerosols and ozone. The model output was bias-corrected and now serves as input for crop models. As a novel contribution, multivariate bias correction was not only performed for the conventional meteorological variables, but also for surface ozone. To analyze compound events affecting crop yield in Europe, a bivariate extension of a statistical method to objectively define extreme events has been developed and changes in frequency of such events in CMIP6 climate projections were investigated. It is also important to link knowledge, observations and experience from producers to the modeling work. For this, we have conducted a literature review to assess the current knowledge of the benefits of adaptation to climate change and air pollution for wheat in Europe. The results indicate that very little work has been done exploring adaptation to air pollution, while far more work covers the benefits of adaptation options for climate change, which range from technical options and management to broader transformational changes in agro-ecology and finance. We have systematically reviewed over 250 journal papers extracting data on yield benefits for a variety of climate change conditions, estimated for both near and medium-term futures. We find that the benefits of adaptation vary by European region and type of wheat, and that the most often explored adaptation options are those that can most easily be modeled by existing crop growth models in combination with global climate change modeling. However, these are not always the adaptation types that might positively influence yield benefits (e.g., barriers to implementing adaptation are often related to finance and agricultural policy). A major aim of the project was to involve stakeholders directly, which has been a challenging task due to the plans for multiple workshops being affected by the COVID-19 situation. Separate interviews and questionnaires with farmers, technicians and companies were conducted, while a multi-stakeholder session was held in Spain, involving, among others, government representatives. Input from stakeholders was collected in terms of their experienced challenges of climate change and air pollution, impacts of adaptive measures and means for adaptation. A factsheet has been produced in multiple languages to inform stakeholders of the impacts of climate change on wheat production in different regions of Europe and the objectives of the SUSCAP project.

As climate change and air pollution will impact crop yields and food supply in Europe, farmers have implemented or are implementing adaptation measures to mitigate yield losses. Our project focused on the interaction between air quality and climate change, which is extremely important as our results indicate that adaptation to climate change may inadvertently increase crop losses due to ozone pollution. With the new generation of crop models developed in this project, we are now able to assess the combined impacts of these stresses in current and future climates. In the process of our stakeholder engagement work, it was found that the effect of ozone pollution on arable productivity is relatively unknown within the agricultural sector. We were therefore able to disseminate information and exchange knowledge directly with farmers, farming organizations, crop breeders, policy makers and other industry stakeholders. This project was trans-disciplinary in that it combined the efforts, knowledge and skills of experimental scientists, crop modelers, remote sensing experts and climate scientists. Combining these different backgrounds, as well as the varying experiences and approaches of multiple European countries, has allowed for opportunities to exchange information and research in a very open manner and will surely facilitate further collaboration on improving the sustainability and future productivity of arable agriculture in Europe.

This project will develop a new generation of process-based models capable of assessing key crop resource use efficiencies (Water Use Efficiency (WUE), Nitrogen Use Efficiency (NUE) and Radiation Use Efficiency (RUE)) that are affected by multiple stresses resulting from air pollution (specifically ozone and aerosol), climate change and CO2 fertilization. We will improve our understanding of the mechanisms by which pollution and climate stress influence these resource use efficiencies so that we can identify promising crop traits and crop management practices that provide adaptation to these stresses. Such adaptation would lead to improved crop growth, development and yield under future pollution and climates enhancing the economic resilience of European arable agriculture. Our consortium of eight world-leading expert groups skilled in climate change and air pollution in relation to crop experimental investigation and modelling will conduct this research with transnational stakeholders from across Europe to co-design appropriate solutions and interventions. We will use recent developments in climate and atmospheric chemistry modelling and statistical analysis to identify the magnitude, frequency, and geographical distribution of different combinations of abiotic stresses that will be prevalent over the coming decades up to 2050. We will apply an ensemble crop modelling approach to identify the future abiotic stress combinations that will be most likely to damage crop resource use efficiency, identifying thresholds and feedbacks that will lead to reduced crop productivity. We will identify the future geographical and temporal distribution of these combined stresses so that we can locate regions in which crop resources are already limiting, and have the potential to become more (or less) limiting in the future. Together these activities will improve the sustainability and future productivity of arable agriculture in Europe.