Evidence of abundant lakes and ponds and the remains of vascular plants, warmth-demanding beetles, sponges, spruce forests…in a newly-discovered organic-rich deposit 480 m above sea level in High Arctic (76.4°N) northwest Greenland indicates the local climate was similar to that of today’s southern Greenland (~60°N) and North America during the Early Pleistocene ice age.
Scientists analyze the habitat temperature thresholds for modern plants, trees, insects, mammals, etc., and compare these values to the climate conditions these same species were living in according to the paleoclimate fossil record to determine how much warmer (or colder) the past was relative to the present.
About 2 million years ago (Early Pleistocene), CO2 levels were estimated to have hovered around 300 ppm.
A glacier site in northwest Greenland, Pingorsuit, sits 480 m above sea level. It is currently covered in “continuous permafrost” that is still 25 cm thick in July (Bennike et al., 2023). Modern mean July temperatures only reach 1-2°C here.
Organic deposits discovered at this site in 2019 reveal the climate was much warmer than today during the Early Pleistocene. Picea mariana (spruce) existed at this High Arctic location at that time, but the growth limit latitude for P. mariana today is only the southern tip of Greenland and North America.
The Early Pleistocene presence of several varieties of vascular plants at Pingorsuit further suggests the site had a sub-Arctic or boreal climate that needed have averaged 10°C or warmer during July, or “at least 9°C higher than at present.”
“At the Pingorsuit Glacier in North-West Greenland, an organic-rich deposit was discovered at an elevation of 480 m above sea level. The sediments contained remains of vascular plants, mosses, beetles, caddisflies, midges, bryozoans, sponges and other invertebrates. The fossils were deposited in a boreal environment with a mean July air temperature that was at least 9 °C higher than at present.”
The Beaver Pond site at 78°N was so warm and permafrost-free during the mid-Pliocene (~3-4 million years ago) that it could accommodate grass-grazing megafauna such as horse and deer. Even camels lived in the High Arctic at this time.
There appears to be no evidence supporting the claim that the High Arctic modern climate is unusually warm relative to the past, or when there were allegedly much lower CO2 ppm values.