Assessing Earth System Responses to Climate Mitigation and Intervention with Scenario-Based Simulations and Data-Driven Insight

Abstract

Given a world increasingly dominated by climate extremes, large-scale geoengineering interventions to modify the Earth’s climate appears inevitable. However, geoengineering faces a conundrum: accurately forecasting the consequences of climate intervention in a system for which we have incomplete observations and an imperfect understanding. We evaluate the potential implications of mitigation and intervention strategies with a set of experiments utilizing historical reanalysis data and scenario-based model simulations to examine the global response to deploying these strategies. Key findings included a global mean surface temperature and total precipitation increases of 1.374\(\pm\)0.481\(^\circ\)C and 0.045\(\pm\)0.567 mm day⁻¹ respectively over the observed period (i.e., 1950–2022). Mitigation and intervention simulations reveal pronounced regional anomalies in surface temperature and erratic interannual variability in total precipitation, with surface temperatures up to 7.626\(^\circ\)C in Greenland, Northern Siberia, and the Horn of Africa down to -2.378ºC in Central Africa and Eastern Brazil, and total precipitation increases of 1.170 mm day⁻¹ in Southern Alaska down to -1.195 mm day^− 1 in Colombia and East Africa. Furthermore, [CH₄] dynamics indicated the potential to alter global and regional climate metrics but presented significant regional and global variability based on scenario deployment. Collectively, intervention and mitigation simulations tended to overestimate the variability and magnitude of surface temperature and total precipitation, with substantial regional deviations and scenario-dependent estimation heterogeneity for [CH₄]. Furthermore, forward projections indicate that both mitigation and intervention scenarios can lead to varied climate responses, emphasizing the complexity and uncertainty in predicting exact outcomes of different geoengineering strategies. By constraining our investigation scope to include monthly surface temperature, total precipitation, and atmospheric methane concentration [CH₄], we find these simulations were capable of accurately capturing departures but unable to perfectly represent patterns of warming and precipitation teleconnections clearly identified in the observational record.