A new paper published in Climate of the Past compares temperature reconstructions of the last interglacial period [131,000-114,000 years ago] to climate model simulations and finds climate models significantly underestimated global temperatures of the last interglacial by ~0.67C on an annual basis and by ~1.1C during the warmest month.
This implies that climate models are unable to fully simulate natural global warming, and the error of the underestimation is about the same as the 0.7C global warming since the end of the Little Ice Age in ~1850. Thus, the possibility that present-day temperatures could be entirely the result of natural processes cannot be ruled out in comparison to the last interglacial period.
Further, during the last interglacial, Greenland temperatures were naturally up to 8C higher and sea levels up to 43 feet higher than today. And, during another interglacial, all of Greenland and West Antarctica melted & sea levels were 79 feet higher. Since this low-CO2 global warming occurred entirely naturally, there is no evidence that global warming during the present interglacial is unnatural or man-made.
|Temperatures during the last interglacial period ~120,000 years ago were higher than during the present interglacial period.|