Exploring the Earth system response to temporary ‘overshoot’ with ACCESS-ESM1.5
Spencer
Authors: Spencer Clark1,2, Andrew King1,2 and Zebedee Nicholls1,3,4
- School of Geography, Earth and Atmospheric Sciences, The University of Melbourne, Australia
- ARC Centre of Excellence for the Weather of the 21st Century, Clayton, VIC, Australia
- Energy, Climate and Environment Program, International Institute for Applied Systems Analysis (IIASA), 2361 Laxenburg, Austria
- Climate Resource, Melbourne, Victoria, Australia
As human-induced warming approaches the 1.5ºC limit of the Paris Agreement, the need to evaluate alternative policy objectives consistent with mitigating the harms of anthropogenic climate change has becoming increasingly pressing. ‘Overshoot’ pathways, those where human-induced warming temporarily exceeds and later declines to or below specific global warming levels, such as 1.5ºC, have been increasingly discussed toward this end. The relative risks and benefits associated with such pathways, however, remains poorly understood, largely owing to a dearth of information from comprehensive Earth System Models (ESMs). In this work, we aim to enhance understanding of projected physical climate risks under temporary overshoot by analysing two novel experiments performed by ACCESS-ESM1.5 and other ESMs. Using the Tier 1 TIPMIP and esm-flat10-cdr Flat10MIP experiments, we analyse how locally and regionally important climate impact drivers, such as climate extremes, respond to overshoot and identify regions where such responses are projected to be non-linear and/or irreversible on human-perceptible timescales. We show that whilst long-term temperature decline under overshoot reverses many important regional climate impacts, the reversibility of ‘time-lagged’ impacts is largely limited. Our results are of relevance to Earth system scientists/modellers and researchers interested in future climate projections and future climate risk.
Keywords: ACCESS-ESM1.5, climate modelling, climate change projections, Earth system modelling, overshoot, negative emissions.
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