Abstract for: Assessing Planetary Boundary Transgressions and Their Causes - Using the World-Earth model FRIDA

The planetary boundaries (PBs) framework defines a "safe operating space" based on nine key Earth system processes. Out of these, four are terrestrial, and their primary driver of transgression is agriculture. To better understand how agricultural activities might further influence the terrestrial PBs, it is essential to model their drivers and interactions over time. We develop a PBs module within FRIDA, representing the climate change PB and the four terrestrial PBs: biosphere integrity, land system change, freshwater use and biogeochemical flows. In total, seven different PB control variables are implemented across the five PBs studied, using both directly related variables in FRIDA and proxies related to the calculations using assumed relationships based on literature. The results show overarching agreement with independent, earlier estimates of PB control variable time series on whether the control variables are in the safe operating space, the zone of increasing risk or the high-risk zone at a given point of time. However, some notable differences still occur. Part of the differences may be attributed to the proxies developed to account for some relevant processes not currently represented in FRIDA. Overall, we demonstrate the general suitability of the FRIDA model for simulating PB trajectories and its potential to represent and analyse their drivers and interactions.