- Vertebrate (Wikipedia)
Vertebrates (/ˈvɜːrtəbrɪts, -ˌbreɪts/) are animals with spinal cords and bony or cartilaginous backbones, including all mammals, birds, reptiles, amphibians and fish. The vertebrates consist of all the taxa within the subphylum Vertebrata (/ˌvɜːrtəˈbreɪtə/) (chordates with backbones) and represent the overwhelming majority of the phylum Chordata, with currently about 69,963 species described.
- Holocene sea-ice dynamics in Petermann Fjord in relation to ice tongue stability and Nares Strait ice arch formation (tc.copernicus.org)
The Petermann 2015 expedition to Petermann Fjord and adjacent Hall Basin recovered a transect of cores, extending from Nares Strait to underneath the 48 km long ice tongue of Petermann glacier, offering a unique opportunity to study ice–ocean–sea ice interactions at the interface of these realms. First results suggest that no ice tongue existed in Petermann Fjord for large parts of the Holocene, raising the question of the role of the ocean and the marine cryosphere in the collapse and re-establishment of the ice tongue. Here we use a multi-proxy approach (sea-ice-related biomarkers, total organic carbon and its carbon isotopic composition, and benthic and planktonic foraminiferal abundances) to explore Holocene sea ice dynamics at OD1507-03TC-41GC-03PC in outer Petermann Fjord. Our results are in line with a tight coupling of the marine and terrestrial cryosphere in this region and, in connection with other regional sea ice reconstructions, give insights into the Holocene evolution of ice arches and associated landfast ice in Nares Strait.
- In the winter of 2006/2007 both ice arches failed to form for the first time in recorded history, causing sea ice to remain mobile in Nares Strait year-round (Kwok et al., 2010; Vincent, 2019) (Fig. 2, Supplement Fig. S1).
- Additionally, the formation of the southern ice arch in Smith Sound is crucial for the annual opening of the North Water Polynya (NOW) (Fig. 1) and the formation of landfast sea ice in Nares Strait (Barber et al., 2001).
- In Nares Strait their formation [ice arches] depends primarily on the sea ice thickness, local wind stresses, and atmospheric temperatures (Barber et al., 2001; Kwok et al., 2010; Samelson et al., 2006).
- Ice arching inhibits sea ice export from the Arctic Ocean and allows the formation of landfast ice in Nares Strait, consisting of a mixture of multi-year drift ice, originating from the Arctic Ocean, and locally formed first-year ice (Kwok, 2005; Kwok et al., 2010).
- Historically, the formation of a northern and southern [ice] arch has been observed in Robeson Channel and Smith Sound, respectively (Fig. 1) (Vincent, 2019).
- In recent decades, however, changes in the ice arch configuration suggest a transition in Nares Strait sea ice dynamics.
- This is associated with a shift from a prominent southern ice arch towards increased importance of the northern arch (Vincent, 2019).