In examining temperature thresholds for the loss of Arctic summer sea ice, the Special Report on Global Warming of 1.5°C (SR1.5; Hoegh-Guldberg et al., 2018) and SROCC assess that a reduction of September mean sea ice area to below 1 million km2, practically a sea ice-free Arctic Ocean, is more probable for a global mean warming of 2°C compared to global mean warming of 1.5°C