Analysis of 21st Century Surface Temperature Trends and Tipping Points

Emerging studies signal imminent "tipping points" due to climate change. This research examines global surface temperature trends using observational data and climate model simulations. Our analysis shows regional disparities in global warming rates, with the Arctic undergoing warming over three times the global mean. Using latitude-dependent temperature simulations from various Coupled Model Intercomparison Project Phase 6 (CMIP6) models, we evaluate their precision against observational data and identify models mirroring historical latitude-based values. Temperature forecasts are derived from ensemble simulations of the Shared Socioeconomic Pathway 2–4.5 (SSP2–4.5) by these vetted CMIP6 models. We identify the projected years when surface temperatures might elevate by 1.5, 2.0, and 2.5°C above preindustrial benchmarks, globally and for specific regions. Particularly in the Arctic, the predictions indicate a significant temperature escalation with potential worldwide implications. Additionally, using the NCAR CESM model, we probe the climate system's reversibility—integral to understanding tipping points. Following the CMIP benchmark experiment, we escalate CO2 concentration by 1% annually. At each decade's outset, we initiate a sensitivity run, retracting CO2 to its starting value for that period. The concluding climate conditions, including surface temperature, sea ice proportion, and sea level ascent, are juxtaposed against their initial states, assessing reversibility across the century. This approach provides a comprehensive assessment of climate system tipping points, highlighting the diverse repercussions of greenhouse gas-driven warming on various climate facets.