There is no apparent connection between Greenland’s ice melt and atmospheric CO2 concentrations.
The ice that blankets Greenland today stands over 3 kilometers high. This ice volume can almost completely vanish – with just a tiny ice cap in the eastern highlands remaining – when CO2 concentrations only reach pre-1750 levels, or 260 to 280 ppm.
For about 280,000 of the last 2.6 million years (encompassing the Pleistocene Ice Age), Greenland was ice-free (Schaefer et al., 2016).
Image Source: Schaefer et al., 2016
For the last few centuries, the volume of ice on the Greenland ice sheet has been much larger than it has been for all of the last 10,000 years (Mikkelson et al., 2018).
Image Source: Mikkelson et al., 2018
Axford et al., 2019 found NW Greenland’s “outlet glaciers were smaller than today from ~9.4 to 0.2 ka BP” (9,400 to 200 years before 1950), and that “most of the land-based margin reached its maximum Holocene extent in the last millennium and likely the last few hundred years.”
“We infer based upon lake sediment organic and biogenic content that in response to declining temperatures, North Ice Cap reached its present-day size ~1850 AD, having been smaller than present through most of the preceding Holocene.”
Greenland was 2.5°C to 3°C warmer than modern on average during the Holocene Thermal Maximum, and peak temperatures were 4°C to 7°C warmer.
Image Source: Axford et al., 2019
The ice melt at the interior of the Greenland ice sheet is flowing more slowly today than it has for 95% of the last 9,000 years – with the Little Ice Age the only period with less ice flow (MacGregor et al., 2016).