Thousands of pingos previously unknown to science have now been mapped by scientists.
As part of the 2020 NWT and Nunavut Geoscience Symposium, which was showcased online this year due to the Covid-19 pandemic, Dr. Stephan Wolfe discussed the results of a recent survey using satellite imagery that confirmed over 2,350 pingos in a 18,500 square-kilometre area in the Tuktoyaktuk Peninsula Region.
“Pingos are ice-filled permafrost hills,” said Wolfe in his presentation. “The 48-metre high Ibyuk pingo exemplifies the nature of many of the conically shaped pingos in the region.
“Many other pingos, however, have much lower land-form relief and are not easily identifiable.”
Conducted by Wolfe, Dr. Peter Morse and Dr. Pouran Behnia for the Geological Survey of Canada, the research was part of efforts to update scientific knowledge of pingo geography, which was last surveyed by aerial photography in 1963.
This new study used Arctic Geographical Information System (ArkGIS) and Google Earth, along with Digital Elevation models (ArcticDEM) — high resolution elevation maps captured by satellites, to develop a more accurate picture.
“We initially identified nearly 2,820 pingo-like features,” said Wolfe. “Using an iterative process between the ArcticDEM and Satellite imagery, we confirmed some-2361 pingos that met both the topographical and optical criteria.”
Wolfe added the surveyors compared their data with the older 1967 dataset to confirm the location of known pingos, which were included in their survey.
“In short, we identified more than 900 new pingos in the region,” said Wolfe. “Some 2,225 pingos occur in the Tuktoyaktuk coastlines and this represents about 94 per cent of pingos in the entire region.”
Most of the pingos surveyed were hydrostatic, or closed systems, where sand saturated with water under a lake holds moisture after the lake itself has dried up.
Wolfe detailed differences in the geology surrounding pingos throughout the Arctic, noting pingos appear both in areas that were buried beneath glaciers during the last ice age, which occurred between 75,000 to 11,000 years ago during the what’s called the Holocene, and areas that were not.
Noting much of the concentration of pingos was distributed along the coastline, which itself was receding in the face of rising sea levels, Wolfe added the rate of pingos deteriorating as they erode and drain into the ocean was likely outpacing formation of new ones.
“Through coastal erosion, many lakes containing Holocene-aged pingos now drain directly into, or are connected to, the Beaufort Sea,” said Wolfe. “Although lake drainage can initiate pingo growth, coastal erosion is a rapid mechanism for pingo degradation, thus the rate of pingo loss along the coast likely exceeds that of formation.”