Studying permafrost changes under different (e.g., glacial/interglacial) and changing (e.g., current various scenarios) climates can potentially advance our understanding of permafrost's responses to climate change and further enable informed policy making for mitigating impacts from permafrost changes. Despite existing studies generally focusing on permafrost change during certain periods, here, we have synthetically examined the changes of the Northern Hemisphere near-surface permafrost during the six periods (Last Glacial Maximum (LGM, similar to 21 ka), mid-Holocene (MH, similar to 6 ka), preindustrial (PI, ca 1850), future 1.5 degrees C and 2.0 degrees C global warming periods, and end of the 21st century), using the surface frost index (SFI) model and outputs of six climate models. Simulated climate anomalies plus present-day observed climatology are used to drive the SFI model in this study. This helps correct systematic biases in permafrost change simulations.The results show that multi-model ensemble extent of present-day near-surface permafrost in the Northern Hemisphere agree well with the observations, with an area bias of 0.27x106 km2 in area (1.8% of the total observed area). Minor deviations (1.55x106 km2) in the simulated present-day permafrost extents across the climate models indicate a low inter-model diversity. In response to changes in annual mean surface air temperature of -10.3 +/- 2.3 degrees C (LGM), +0.1 +/- 0.5 degrees C (MH), +2.6 +/- 0.7 degrees C (1.5 degrees C global warming, RCP4.5), +3.6 +/- 1.0 degrees C (2.0 degrees C global warming, RCP4.5), and +5.0 +/- 1.3 degrees C (end of the 21st century, RCP4.5) in present-day permafrost regions relative to the PI, the changes in near-surface permafrost area are +33%+/- 30% (LGM), -13%+/- 6% (MH), -25%+/- 8% (1.5 degrees C warming, RCP4.5), -35% +/- 10% (2.0 degrees C warming, RCP4.5), and -55%+/- 12% (end of the 21st century, RCP4.5), respectively. From the LGM to the future, near-surface permafrost extent substantially decreases, underlining its high sensitivity to climate change and implying its potentially profound impacts in a warming future.

来源平台：SCIENCE CHINA-EARTH SCIENCES