Projected Regional 1.50 & DEG;C and 2.00 & DEG;C Warming Threshold-crossing Time Worldwide Using the CMIP6 Models

The Paris Agreement aims to limit global warming to well below 2.00 degrees C and pursue efforts to limit the temperature increase to 1.50 degrees C. However, the response of climate change to unbalanced global warming is affected by spatial and temporal sensitivities. To better understand the regional warming response to global warming at 1.50 degrees C and 2.00 degrees C, we detected the 1.50 degrees C and 2.00 degrees C warming threshold-crossing time (WTT) above pre-industrial levels globally using the Coupled Model Intercomparison Project phase 6 (CMIP6) models. Our findings indicate that the 1.50 degrees C or 2.00 degrees C WTT differs substantially worldwide. The warming rate of land would be ap-proximately 1.35-1.46 times that of the ocean between 60 degrees N-60 degrees S in 2015-2100. Consequently, the land would experience a 1.50 degrees C (2.00 degrees C) warming at least 10-20 yr earlier than the time when the global mean near-surface air temperature reaches 1.50 degrees C (2.00 degrees C) WTT. Meanwhile, the Southern Ocean between 0 degrees and 60 degrees S considerably slows down the global 1.50 degrees C and 2.00 degrees C WTT. In 2040-2060, over 98.70% (77.50%), 99.70% (89.30%), 99.80% (93.40%), and 100.00% (98.00%) of the land will have warmed by over 1.50 degrees C (2.00 degrees C) under SSP (Shared Socioeconomic Pathway) 1-2.6, SSP2-4.5, SSP3-7.0, and SSP5-8.5, respectively. We conclude that regional 1.50 degrees C (2.00 degrees C) WTT should be fully considered, especially in vulnerable high-latitude and high-altitude regions.