Evolving relationship of Nares Strait ice arches on sea ice along the Strait and the North Water, the Arctic’s most productive polynya

Abstract

Nares Strait, the waterway that separates northwest Greenland from Ellesmere Island, is a major pathway along which sea ice leaves the Arctic, including the planet’s oldest and thickest sea ice that is experiencing an accelerated loss. Ice arches that develop during the winter at the Strait’s northern or southern terminus can remain stable for months at a time during which the transport of sea ice ceases. The Arctic’s most productive polynya, the North Water (NOW) or Pikialasorsuaq (West Greenlandic for ‘great upwelling’) forms at the Strait’s southern end. There is evidence that a warming climate and the concomitant thinning of Arctic sea ice is weakening the arches and it has been proposed that this may impact the stability of NOW and the complex ecosystem that it sustains. Here we employ a categorization of recent winters with respect to the presence or absence of ice arches to explore their impact on sea ice along the Strait and over the NOW. We find that winters during which a southern ice arch is absent are associated with a reduced and thinner ice cover along the Strait with ice conditions over the NOW similar to that during winters with a southern arch. In winters, without a southern arch, there is also an acceleration of the winds along the Strait that contributes to the presence of reduced ice cover. Ocean color remote sensing data suggests that current levels of primary productivity over the NOW are independent of the presence or absence of an ice arch. The results suggest more research is needed to assess the stability of the NOW, with respect to reduced ice cover and primary productivity, in a future where ice arches cease to form along Nares Strait.

Contribution of ice dynamics along Nares Strait to the stability of ice arches

“…Two flux gates were used to calculate the ice area flux (Figure 1). The one situated at the northern end of Nares Strait is used in previous studies 2,11 . A southern flux gate within Kane Basin was also used.…”

“…The high winds that flow through the narrow opening of Smith Sound also contribute to the formation of the NOW by sweeping any ice downstream 16,17 . Indeed, it has been argued that even during winters without an arch present, the winds along Smith Sound are strong enough to reduce ice cover within the NOW region 11 . The presence of an arch has, in the past, allowed migration between Inuit communities in Canada and Greenland, which has supported the transfer of technology across Nares Strait 18 .…”

“…During the period that an arch is present, there can be a significant drop in the ice transport along the Strait 1,2,11 . Consequently, the presence or absence of an arch can have climate and ecosystem impacts beyond Nares Strait.…”

“…This allowed for higher temporal resolution in the ice transport and the date of arch formation. The time series has been extended 11 to January 2022 with the addition of SAR imagery from the RADARSAT Constellation Mission (RCM), thus further maintaining high temporal resolution over the Strait. Here, we further extend the time series to June 2023.…”

Marine diatoms record Late Holocene regime shifts in the Pikialasorsuaq ecosystem

“…Historically, the ice arch blocks the inflow of ice from the Lincoln Sea and Kane Basin and promotes continuous mechanical removal of newly formed sea ice within the NOW by ocean currents and the polar easterlies channeled through the strait. Near the Northwest Greenland coast, sensible heat is also brought near the surface by upwelling of the relatively warm West Greenland Current, which further dampens sea‐ice growth (Melling et al, 2001; Mundy & Barber, 2001; Steffen, 1985) and can contribute to polynya formation even in the absence of an ice arch (Moore et al, 2023). In addition to these processes, strong tide‐induced movement of ice contributes to open waters over the short term (Vincent & Marsden, 2008).…”