Background information for the ISSI website regarding our meetings

Title: Arctic change and Polynyas: Focus on the Northeast Water Polynya and North Water Polynya/Nares Strait system

This meeting is the first in a series of meetings and workshops concentrating on the changing nature of Arctic Polynyas.  Two polynya systems were identified for further study.  These were (a) the Northeast Water Polynya system which is situated over the continental shelf region of NE Greenland and (b) the North Water Polynya/Nares Strait system which is located between Ellesmere Island (Canada) and Greenland.  The functioning of both these systems have undergone change in recent years.
 
The establishment of an International Polar Year (IPY) Data Announcement of Opportunity by the European Space Agency has enabled both the Northwater/Nares Strait (PI: Preben) and Northeast Water (PI: Wilkinson) to be studied in detail through remotely sensed images.  This funding, welcome as it is, focused solely on the acquisition of satellite data and not collaborative dialogue or workshops between international experts in these regions. 
 
The recent opening up of the International Space Science Institute (ISSI) to the Earth science community has given us the opportunity to assemble a team of international scientists, who have worked in these regions for many years, to discuss among other things:
Our first meeting is scheduled for February 27-29 2008 and will concentrate on the Northwater/Nares Strait region. The participants in the meeting are:
 
Prof. David Barber (Can)
Prof Jody Deming (USA)
Dr Rene Forsberg (Den)
Prof Preben Gudmandsen (Den)
Dr Susanne Hanson (Den)
Dr Sine Munk Hvidegaard (Den)
Dr Ron Kwok (USA)
Dr Andreas Muenchow (USA)
Dr Roger Samelson (USA)
Prof Leif Toudal (Den)
Dr Jeremy.Wilkinson (UK)
 
Northwater/Nares Strait
Whilst the Nares Strait region is small is size it is of global importance.  For example it forms part of the global hydrological cycle as it has the deepest outflow in the Canadian polar shelf (max sill depth: 220 m ) and therefore connects the Arctic to the north Atlantic.  It also the conduit for the export of sea ice from the Arctic (second only to Fram Strait) and the export of


significant quantities of glacial ice from the Greenland Ice sheet.  This freshwater flux plays a significant role in the Thermohaline Circulation  (THC) of the world oceans.  The region is also home to the North Water Polynya (NOW).  A Canadian led international programme studied this polynya in great detail and showed that it is the most biologically productive polynya in the whole of the Arctic. Recently the International Arctic Polynya Programme stated the following about the NOW (IAPP: PACE document, 2004).
The North Water has been a reliably recurrent and high-production ecosystem for recorded history, as recently confirmed on the century scale by the marine sedimentary record (Hamel et al., 2002).  The main players (from viruses to whales) and processes (from atmospheric exchange to sediment burial) governing the current functioning of this ecosystem are known (Deming et al., 2002).  The internal factors accounting for the temporal and spatial disposition of the polynya are unambiguous: e.g., the timing and force of the wind arriving from the west and the formidable ice bridge that straddles Kane Basin during the open-water season.  Examination of two decades of satellite imagery suggests that the physical system is poised for change, given the evidence that features of the ice bridge have been weaker in recent years (Barber et al., 2001).  If an external change in Arctic Ocean circulation also occurs (Johnson et al., 1999), then the chemical make-up of the source waters to the polynya may well shift.  Tremblay et al. (2002a) argue that the nitrate to silicate ratio is delicately poised now.  A shift away from silica in the source waters may reduce the extent and magnitude of the diatom bloom in the North Water, which in turn will affect the higher trophic levels.  There is a need for ongoing measurements in the North Water in particular, so that the existing three-year NOW data sets can comprise the beginning of the long-term database required to make and to test predictions (IAPP: PACE document, 2004).

Northeast Water Polynya
The Northeast Water Polynya (NEW), which forms each spring over the continental shelf of NEG, is one of the largest and most consistently recurring polynyas in the Arctic

 (NEWATER, 1993). The importance of the region was highlighted by the Arctic Ocean Sciences Board, through the International Arctic Polynya Programme, whose first programme (NEWATER) was directed to the region in the early 1990s. The NEWATER programme dataset (multidisciplinary) provides a valuable baseline against which we can judge consequences of subsequent and future climate change (Overland et al., 1995, Hirch and Deming, 1997). This dataset is particularly valuable as it the only multidisciplinary dataset available from a time before significant change was detected in the Arctic (early 1990s). Since NEWATER the area of the NEW polynya has slowly increased steadily in size.  In the summer of 2001 the dramatic northerly retreat of sea ice in the East Greenland Current (EGC) united with the polynya to form what one could describe as an almost open continental shelf sea. This scenario, possibly unprecedented in recorded history, continued for the next four years and led to the NEW being described as having morphed into the Marginal Ice Zone (MIZ) (Smith and Barber, 2007). In fact one could legitimately ask if there is still a NEW polynya or has it ceased to function as such?
However in the summer of 2005, which corresponded to a new minimum in the extent of sea ice in the Arctic, the NEW returned, albeit smaller than usual. The continued retreat of Arctic sea ice continued in 2006 and in 2007 it surpassed all previous records, reducing to an area of only 4.1 million km2 (NSIDC, 2007). These years were associated with a significant increase in the amount of ice over the NEG continental shelf, which in turn led to the area of the NEW being substantially smaller than the mean (Fig. 2). In fact the 2007 NEW was the smallest since satellite records began over 30 years ago; it could almost be discribed as non-existent. Thus the likely response of the polynya system to Arctic warming is now unclear. Until recently the response of the polynya system was consistent with an ice retreat and conversion into a MIZ. Recent events suggest that a plausible alternative fate is actually a reduction or near-disappearance of the NEW polynya, possibly driven by an increased export of ice through Fram Strait.
What is clear is that the NEW polynya has experienced a fundamental shift in its operation since the early 1990s. This undoubtedly affects the physical, biological and chemical functioning in the polynya, and as such must impact ecosystem dynamics. Although a few small-scale disciplinary studies have been conducted since NEWATER, no systematic revaluation of the physical, biological and chemical processes has been undertaken.