JULES EMulator of ecosystem services (JEM)

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Ecosystems provide many services, such as timber, food, and water. They are a natural protection against floods, store carbon, and are locations of cultural heritage and recreation. To be sustainable and profitable, future landscape decisions need to consider the various services provided by ecosystems as well as their responses to climate change. The UK's commitment to reducing emissions (to at least 80% below 1990 levels by 2050) means that carbon storage and greenhouse gas emissions from land are central to future land use and management. More ambitious emission reduction targets and their implications are currently being discussed, increasing the need to build land use decisions upon an understanding of the integrated water and biogeochemical cycles. Process-based land surface models are excellent tools for predicting carbon, water, and surface heat exchanges between the land and atmosphere. The UK's community land surface model, JULES, is used in the Met Office Unified Model (UM) framework for applications ranging from climate change to weather forecasting. JULES predicts productivity of vegetation, carbon accumulation in vegetation and soils, soil water content, runoff, and emissions of greenhouse gases from vegetation and soils - meaning it can be used for evaluating the impacts of land use change and climate change on several ecosystem services. Within the UM, JULES is run at a km-scale resolution for weather forecasting. JULES is also used for evaluating the global carbon cycle: for example, each year JULES is used to calculate the net land sink of carbon and emissions due to land use change in the Global Carbon Project. However, in these simulations the spatial resolution (>50km) is inadequate for addressing landscape-scale issues. The computational cost of running JULES at km-scale resolution is very high. At a 1.2km resolution, there were nearly 80,000 grid cells. Running on 144 cores, a 10-year simulation took 70 hours. Decisions on land use changes should incorporate longer timescale changes and uncertainty quantification. An emulator of JULES would allow for more robust statistical calculation of changes in carbon stocks and the water cycle and their uncertainty and open the way for better calibration of JULES. During this short project we will design and build emulators of JULES to inform future evaluation of ecosystem services related to the carbon and water cycles.