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

The Paris Agreement aims to limit global warming to well below 2.00°C and pursue efforts to limit the temperature increase to 1.50°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°C and 2.00°C, we detected the 1.50°C and 2.00°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°C or 2.00°C WTT differs substantially worldwide. The warming rate of land would be approximately 1.35–1.46 times that of the ocean between 60°N–60°S in 2015–2100. Consequently, the land would experience a 1.50°C (2.00°C) warming at least 10–20 yr earlier than the time when the global mean near-surface air temperature reaches 1.50°C (2.00°C) WTT. Meanwhile, the Southern Ocean between 0° and 60°S considerably slows down the global 1.50°C and 2.00°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°C (2.00°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°C (2.00°C) WTT should be fully considered, especially in vulnerable high-latitude and high-altitude regions.