During the last interglacial (LIG) 127 to 119k years ago, when CO2 levels were said to be only 275 ppm, Greenland’s Camp Century surface was ice free, vegetated. Today this same site is buried under a 1.4 kilometers-high ice sheet.
The Arctic was sea ice free during the LIG (Diamond et al., 2021).
Image Source: Diamond et al., 2021
Forests extended to the coasts of the Arctic Ocean during the last interglacial (Sommers et al., 2022). The wasting of the Greenland ice sheet during the LIG translated into 3 meters of sea level equivalent (SLE) from Greenland alone.
As mentioned, Greenland locations that are today covered in 1,400 meters of ice (Christ et al., 2021) were ice-free and covered with vegetation during the LIG (Sommers et al., 2022).
Image Source: Sommers et al., 2022
The Earth’s melted glaciers and Antarctic ice sheet added another 3-6 m of water to the ocean basins, resulting in global sea levels 6-9 meters higher than today during the LIG (Clark et al., 2020).
Image Source: Clark et al., 2020
For some reason it is assumed by mainstream scientists that CO2 has been driving changes to the Greenland ice sheet in recent decades even though measurements indicate the CO2 greenhouse effect (GHE) impact is close to 0 W/m² over Greenland.
The CO2 GHE is said to be as “comparatively weak” for Greenland as it is for Antarctica (-2.9 W/m² to +1 W/m²), a location where increasing CO2 leads to surface cooling, not warming (Schmithusen et al., 2015).
Image Source: Schmithusen et al., 2015
In other words, there is no past or present evidence to suggest the Greenland ice sheet is climatically responding to changes in atmospheric CO2 concentrations.