Carbon cycle feedbacks of CMIP6 models under overshoot scenarios

Abstract:

There is a growing gap between the current annual emissions of greenhouse gases and emission levels required for achieving the 2 °C temperature target of the Paris Agreement. Understanding the feasibility and the implications of a temperature overshoot is an increasingly relevant research issue. Here we explore the carbon cycle feedbacks over land and ocean in the overshoot scenario SSP5-3.4 OS using an ensemble of CMIP6 earth system models (ESMs). We analyze the spatiotemporal change of carbon concentration (beta) and carbon-climate (gamma) feedbacks. Our preliminary results suggest that these feedbacks are amplified, i.e. beta becomes more positive and gamma becomes more negative, during the ramp-down stage of overshoot in all ESMs, despite the difference in spatial patterns. We will discuss these inter-model differences and attempt to explore the implications of these feedbacks by using simple climate models under a range of overshoot scenarios.