Future changes in coverage of 1.5 °C and 2 °C warming thresholds

The areas covered by 1.5 degrees C and 2.0 degrees C warming thresholds under RCP2.6, RCP4.5, and RCP8.5 were analyzed based on 22 CMIP5 models. More than 90% of the model runs are in agreement that by the end of the 21st century, near-surface air temperature changes over similar to 5% (similar to 2%), similar to 40% (similar to 18%), and similar to 92% (similar to 86%) of the globe will cross the 1.5 degrees C (2.0 degrees C) threshold under RCP2.6, RCP4.5, and RCP8.5, respectively. Under RCP8.5, nearly the whole of North America, Europe + Russia, Africa, and Asia-Russia will cross the 1.5 degrees C (2.0 degrees C) threshold in similar to 2050 (similar to 2060), while the coverage rates over South America and Oceania are similar to 80% (similar to 75%) and similar to 50% (similar to 30%), respectively. The threshold-onset time (TOT) for 2 degrees C warming is earliest over Europe + Russia and North America, followed by Africa, Asia-Russia, South America, and finally Oceania under the RCP4.5 and RCP8.5 scenarios. The TOT for 1.5 degrees C is similar to 10-30 years ahead of that for 2.0 degrees C. (C) 2017 Science China Press. Published by Elsevier B.V. and Science China Press. All rights reserved.