Journal of Climate Change, Disaster Risk and Resilience Studies
Storyline-Based Attribution of Polar Heat Extremes Reveals Nonlinear Climate Change Amplification Pathways
Abstract
Kamal Singh Kunwar
Polar heat extremes represent some of the most rapid and impactful manifestations of ongoing climate change, yet the physical processes governing their intensification remain only partially constrained. In particular, the role of coupled atmospheric and radiative feedbacks in amplifying these events is not well quantified within current attribution frameworks. Here, we apply a storyline-based attribution approach combined with high-resolution, non-hydrostatic regional climate simulations to isolate the contribution of anthropogenic forcing and diagnose nonlinear amplification processes during the March 2022 East Antarctic heatwave. By constructing physically consistent preindustrial and present- day counterfactual climates, we separate large-scale thermodynamic forcing from internal feedback-driven responses. Our results indicate that anthropogenic warming accounts for approximately 60–70% of the near-surface temperature anomaly. In addition, we identify a distinct nonlinear amplification signal arising from coupled cloud–radiative and water-vapor feedbacks, which contributes an additional 23–27% of event intensity. This amplification is associated with enhanced downward longwave radiation under anomalously moist atmospheric river conditions, producing localized surface warming of up to 9.8°C. Under a +2°C global warming scenario, these feedbacks intensify further, increasing amplification strength by approximately 18% and expanding the spatial extent of melt-sensitive coastal regions. The results suggest that nonlinear interactions between moisture transport, cloud microphysics, and surface energy balance are critical but underrepresented drivers of extreme Antarctic warming. These findings highlight the need for improved representation of high-resolution radiative–dynamical coupling in climate models to reduce uncertainty in projections of Antarctic ice-sheet mass loss and its contribution to future sea-level rise.