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

<p>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&#8217;s oldest and thickest sea ice that is experiencing an accelerated loss.&#160;&#160; &#160;&#160;Ice arches that develop during the winter at the Strait&#8217;s northern or southern terminus can remain stable for extended periods during which the transport ceases. The Arctic&#8217;s most productive polynya, the North Water (NOW) or Pikialasorsuaq (West Greenlandic for &#8216;great upwelling&#8217;) forms at the Strait&#8217;s southern end in part due to the presence of a nearby southern arch.&#160; 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 lead to detrimental changes to the NOW. Here we use examples from recent years to explore the impact that the absence of a southern arch has on the NOW.&#160; We find that winters with no southern ice arch are associated with a northward expansion of the NOW characterized by reduced &#160;and thinner ice cover as well as enhanced&#160; primary productivity.&#160;&#160; In these years, there is an acceleration of the winds along the Strait that assists in the expansion.</p> <p><strong>&#160;</strong></p>