When humans first arrived in Greenland more than 4000 years ago, they may have crossed an oasis in the middle of the sea ice as they made their way from Canada and across the Nares Strait.
This oasis, known as the North Water polynya, is an area of open water that forms in an otherwise barren environment. Polynyas form only at certain times of the year and at certain latitudes where sea ice normally prevails. Today, the North Water polynya provides a waterway to several Indigenous communities and key Arctic species. But it is very vulnerable to climate warming and thinning of sea ice.
A new study published in Nature Communications now reveals a 6000-year history of the North Water polynya and reveals how periods of relative stability coincide with the history of human settlement in the region.
“Our study uses many lines of evidence and reveals a stable, biological oasis around 4400–4200 years ago, when the first humans arrived in Greenland,” says lead author Sofia Ribeiro, senior scientist at the Geological Survey of Denmark and Greenland (GEUS).
A mystery gap explained
The new study combines a range of innovative analyses of marine and freshwater sediments to track over 6000 years of variation in the stability and productivity in and around this unique and globally important Arctic ecosystem.
Scientists now know the likely date of genesis of the North Water polynya was around 4400 years ago – coincident with the first recorded arrival of humans in Greenland.
However, at other times, climate warming led to instability and even a collapse of the Polynya for up to 1000 years.
“Climate forcing during warm periods led to polynya instability and a collapse of productivity from around 2200–1200 years ago,” says Ribeiro. “This overlaps with this so-called ‘mystery gap’ – a time when archaeological studies point to Greenland being uninhabited.”
The resistance and resilience of this delicate balance in the North Water polynya over the past 6000 years, may shed light on how it may behave in the face of current climate warming.