Accelerated energy transitions and the Earth system

Staying below 1.5°C and returning to 350ppm require much more ambitious and radical actions than currently envisioned. This necessitates different modelling approaches too, transcending current economically optimized equilibrium models. Planetary boundaries need to span the frame for transition modelling, e.g. by setting sustainable limits for renewable energy potentials or incorporating the need to return to 350ppm, which induces negative emissions at a massive scale. Furthermore, building renewable infrastructure needs energy and this feedback loop becomes decisive when accelerating transitions. It also needs materials: speed and pathways of mobilizing materials are pivotal for impacts on planetary boundaries and the energy needed for the transition. Initial modelling with a simple, global system dynamics model suggest that it is still possible energetically to stay below 1.5°C and return to 350ppm this century; however, this requires to keep energy demand and energy storage low.