A large portion of the Greenland ice sheet that is today over 500 m thick did not exist during the Early to Mid Holocene.
Prudhoe Dome (PD), a 2500 km² section of northwestern Greenland’s ice sheet (GIS), is today 500 to 600 m thick (Walcott-George et al., 2026).
Approximately 6000-8000 years ago, or when atmospheric CO2 was alleged to be ~260 ppm, PD had deglaciated completely, exposing the soil to sunlight.
The primary mechanism for the PD deglaciation was the estimated 3-7°C warmer-than-present regional temperatures. This warming and the consequent ice cap minima was said to be “Arctic-wide”.
Starting ~4000 years ago the GIS gradually began thickening until it recently reached its modern glaciated state, with glaciation peaking in the 1800s.
This is just a local proxy — a rough estimate just for the summer months — of a very tiny 0.115% of Greenland, a country that is only 0.43% of Earth’s surface.
This is a local summer “weather report” that has nothing to do with the global average temperature of the time.
Significantly Warmer Temperatures:
Regional summer temperatures during this period (part of the Early to Mid-Holocene) were estimated to be 3°C to 7°C (5.4°F to 12.6°F) warmer than present-day levels. Greenland covers approximately 0.43% (or about 0.425%) of the Earth’s total surface area, making it a significant but relatively small fraction of our planet’s vast expanse
[…] From No Trick Zone […]
ABSTRACT:
Greenland ice-core records provide an exceptionally clear picture of many aspects of abrupt climate changes, and particularly of those associated with the Younger Dryas event, as reviewed here. Well-preserved annual layers can be counted confidently, with only 1%
errors for the age of the end of the Younger Dryas 11,500 years before present. Ice-flow corrections allow reconstruction of snow accumulation rates over tens of thousands of years with little additional uncertainty.
please see https://www.ncei.noaa.gov/pub/data/paleo/icecore/greenland/summit/gisp2/isotopes/gisp2_temp_accum_alley2000.txt
About half way down the data is :
2. Accumulation rate in central Greenland
Column 1: Age (thousand years before present)
Column 2: Accumulation rate (m. ice/year)
Age Accumulation
1st 0.144043 0.244106
last 2
48.9746 0.091739
49.0034 0.091599
So 49,000 years and there are no negative numbers for Accumulation. Or every time period has increased volume. On the summit, Greenland over the last 49,000 years has only gained ice.