In north-eastern Siberia the active mid-ocean #Gakkel #Ridge interacts with the continental shelf of the Laptev Sea. Extension has affected the shelf since at least the Early Tertiary and has resulted in the formation of a complex horst and graben system. The Laptev sea is known as the birthplace of ice. Every year, ice forms along its coasts in the autumn before being pushed west across the Arctic Ocean to #Greenland and Norway’s Svalbard archipelago, where it breaks up come spring.

Contrasts in Arctic shelf sea-ice regimes and some implications: Beaufort Sea versus Laptev Sea

The winter ice-regime of the <80 km wide Alaskan Beaufort Sea shelf is characterized by compression and shearing, resulting in the formation of major grounded pressure ridge systems stabilizing the fast ice on the mid-shelf, and essentially no open-water areas. In contrast, the winter ice-regime of the 500-km wide Laptev Sea shelf is controlled by winds blowing from land to sea, and is therefore dilational. A perennial polynya borders the hundreds of kilometers-wide and very smooth fast ice offshore. In this body of open water, rapidly forming ice is continuously advected offshore by the mean wind field, making the Laptev Sea the single major ice factory for the Arctic Ocean and #Transpolar #Drift. Conversely, with summer warming this dark polynya turns into an area of high heat gain, which results in the retreat of the ice edge to a much higher latitude and greater distance (>500 km) from the mainland than in the Beaufort Sea. As a result, the annual freeze-up does not incorporate old, deep-draft ice, and with a lack of compression, such deep-draft ice is not generated in situ, as on the Beaufort Sea shelf.
The Laptev Sea has as much as #1000 km of fetch at the end of summer, when freezing storms move in and large (6 m) waves can form. Also, for the first three winter months, the polynya lies inshore at a water depth of only 10 m. Turbulence and freezing are excellent conditions for sediment entrainment by frazil and anchor ice, when compared to conditions in the short-fetched Beaufort Sea. We expect entrainment to occur yearly. Different from the intensely ice-gouged Beaufort Sea shelf, #hydraulic #bedforms probably dominate in the Laptev Sea.
Corresponding with the large volume of ice produced, more dense water is generated in the Laptev Sea, possibly accompanied by downslope sediment transport. Thermohaline convection at the midshelf polynya, together with the reduced rate of bottom disruption by ice keels, may enhance benthic productivity and permit establishment of open-shelf benthic communities which in the Beaufort Sea can thrive only in the protection of barrier islands. Indirect evidence for high benthic productivity is found in the presence of walrus, who also require year-round open water. By contrast, lack of a suitable environment restricts walrus from the Beaufort Sea, although over 700 km farther to the south. We could speculate on other consequences of the different ice regimes in the #Beaufort and #Laptev Seas, but these few examples serve to point out the dangers of exptrapolating from knowledge gained in the #North American #Arctic to other shallow Arctic shelf settings.

The Laptev Sea hasn’t frozen

Every year, that is, until this one. For the first time since records began, the #Laptev #Sea has not begun to freeze by late October. This is only the latest example of how climate change is rapidly transforming the Arctic. Scientists from the Polar Science Center worry that it could have damaging knock-on effects across the region. Due to climate change and weather anomalies, the area lost 50% of its ice coverage in its east last year, far exceeding previous models. If the Laptev Sea’s ice-free season continues to get longer, newly formed sea ice will not be able to spread to other parts of the Arctic Ocean before another melting season starts, threatening the region’s ecosystem, scientists say. A loss of ice from the Laptev Sea could also cause ice in other regions to melt faster by exposing more dark ocean surface to sunlight and creating a feedback loop of accelerating warming.
The latest record comes amid a series of abnormal heatwaves and extreme weather events like wildfires and droughts in #Siberia and the #Arctic that have been linked to climate change. During last month’s heatwave along Russia’s Arctic coast, the shores of the Barents Sea saw hotter temperatures than beaches in #Italy and southern #France.
Between #January and #June, temperatures across the region were more than 5°C warmer than the recent average (calculated between 1981 and 2010). In some spots they were more than 10°C above average. On June 20th in the town of #Verkhoyansk in north-eastern #Siberia thermometers read 38°C—the highest ever recorded north of the #Arctic #circle, according to #Russia’s meteorological service.
This extraordinary heatwave has drawn the attention of the World Weather Attribution (WWA) project, a collaboration among #climate #researchers who specialize in quantifying the role that climate change plays in extreme-weather events (such as particularly large and devastating floods, droughts or cyclones, as well as heatwaves). Such events occurred even before #modern #industries began churning out large quantities of greenhouse gases. But the resulting warming of global temperatures can make #extreme #weather likelier or more severe.