The graph here is from the paper Co-production of knowledge reveals loss of Indigenous hunting opportunities in the face of accelerating Arctic climate change in Environmental Research by Donna D W Houser, et. el. (8/24/2021). From the discussion:
Overall, our analyses indicate that the ugruk harvesting season for Qikiqtaġruŋmiut hunters is being compressed by the shorter spring ice breakup period. Indeed, if we summarize across our time-series from 2003 to 2019, Kotzebue Sound now clears of sea ice ∼22 d earlier (figure S3) and is the primary factor contributing to a shrinking ugruk hunting season.
A new Indigenous-led study documents how ice loss is changing seal hunts by Yereth Rosen (9/6/2021) is non-technical summary of the paper and when an article has a rate in it we can use it in calculus:
From 2003 to 2019, the seal hunting season diminished by about a day a year, with most of that change happening at the end of the season, according to the study, published in the journal Environmental Research Letters.