Study 1 - numerical analysesThis zip file contains a set of data files This study is comprised of an ensemble of 10 simulations for each of the 4 focal grid cells listed in Table 4 of the manuscript. The outputs were used to generate Figure 2 of the manuscript. Refer to the ReadMe-Study1.txt for a detailed description of output files and ReadMe-ModelSetup.txt file for a more detailed description of the model setup files.Study 2 - Individual and community predictionsData outputs generated by the Madingley General Ecosystem Model for single simulations in the four focal grid cells listed in Table 4 of the manuscript. These outputs were used to generate Figures 3 and 4 of the manuscript. A comprehensive description of the outputs is given in the ReadMe-Study1.txt file. Refer to ReadMe-ModelSetup.txt for a description of the model setup files.Study 3 - community predictions at observation locationsOutputs from the Madingley model for Study 3 listed in Table 3 of the manuscript. The data file is comprised of an ensemble of 10 simulations for each of the 13 focal grid cells listed in Table S3. Model outputs files are described in detail in 'ReadMe-Study3.txt', whilst model setup files are detailed in the 'ReadMe-ModelSetup.txt'.Study 4 - Global predictionsOutputs from the Madingley model for Study 4 of Table 3 of the manuscript. This study is comprised of one simulation over a global model grid at 2 degree by 2 degree resolution and extending from 65 degrees north to 65 degrees south, and from 180 degrees west to 180 degrees east. Outputs files are described in more detail in 'ReadMe.txt' and model setup files are described in 'ReadMe-ModelSetup.txt'.

Anthropogenic activities are causing widespread degradation of ecosystems worldwide, threatening the ecosystem services upon which all human life depends. Improved understanding of this degradation is urgently needed to improve avoidance and mitigation measures. One tool to assist these efforts is predictive models of ecosystem structure and function that are mechanistic: based on fundamental ecological principles. Here we present the first mechanistic General Ecosystem Model (GEM) of ecosystem structure and function that is both global, and applies in all terrestrial and marine environments. Functional forms and parameter values were derived from the theoretical and empirical literature where possible. Simulations of the fate of all organisms with body masses between 10 µg and 150,000 kg (a range of 14 orders of magnitude) across the globe led to emergent properties at individual (e.g. growth rate), community (e.g. biomass turnover rates), ecosystem (e.g. trophic pyramids) and macro-ecological scales (e.g. global patterns of trophic structure) that are in general agreement with current data and theory. These properties emerged from our encoding of the biology of, and interactions among, individual organisms without any direct constraints on the properties themselves. Our results indicate that ecologists have gathered sufficient information to begin to build realistic, global and mechanistic models of ecosystems, capable of predicting a diverse range of ecosystem properties and their response to human pressures.