Warm Atlantic water drives the climate in the Arctic
Top image: Benoit Bizet/UNIS
During the last 132,000 years, the Arctic climate varied significantly and this was closely related to the strength and variability in the inflow of Atlantic Water to the Arctic. This emphasizes the importance of considering regional environmental parameters and feedback mechanisms in reconstructions of the past climate, according to a new PhD thesis by Teena Chauhan. The thesis will be defended at UNIS on Thursday 27 August 2015.
21 August 2015
Press release from the University Centre in Svalbard (UNIS) and UiT – The Arctic University of Norway
Reconstruction of the past ocean processes is vital for the understanding of natural variability of climate and its forcing mechanisms. In this study by UNIS PhD candidate Teena Chauhan, sediment cores from poorly studied regions of the north-western and northern continental margin of Svalbard have been investigated in order to reconstruct variability of the Atlantic Water inflow to the Arctic during the last interglacial-glacial-interglacial period in the late Quaternary (last 132,000 years).
This study focuses on the reconstruction of the variability of Atlantic Water inflow to the Arctic Ocean and its influence on the Svalbard-Barents Sea Ice Sheet (SBIS), sea-ice cover, variations in the bottom current strength and the depositional environment in the past. For this reconstruction, the distribution patterns of planktic and benthic foraminiferal assemblages, oxygen and carbon stable isotopes in planktic and benthic foraminifera (single-celled protists with shells), ice-rafted debris, grain size of the sediment in particular sortable silt, and organic carbon content from two sediment cores were investigated.
The results show that variable strength of the subsurface Atlantic Water together with insolation has influenced the extent of the sea-ice cover and the stability of the SBIS since 132,000 years before present (Termination II). Besides, distinct increase in freshwater flux from melting of glacier ice during deglaciation periods at around 60,000 years (MIS 4/3) and between 19,000 and 11,500 years (MIS 2/1) also had significant influence on the oceanography through stratification of the upper water column and weakening of the ocean circulation. This led to poor ventilation at the sea bottom and expansion of sea-ice cover at the surface. The influence of these ‘climate drivers’ on the local sedimentary and oceanographic environment varied significantly. This emphasizes the importance of considering regional environmental parameters and feedback mechanisms in reconstructions of the past climate.
Chauhan’s PhD thesis entitled “Late Quaternary paleoceanography of the northern continental margin of Svalbard”, will be defended on 27 August 2015 at 12:30 in auditorium Lassegrotta at UNIS. The candidate will hold a trial lecture the same place at 10:15 entitled “The role of North Atlantic deep water in millennial-decadal climate change”.
About the candidate:
Teena Chauhan was born in 1981 in Jabalpur, Madhya-Pradesh, India. She completed her master’s degree in Marine Geology at Cochin University of Science and Technology, Cochin, Kerala, India. She worked 2 years at the National Institute of Oceanography, Goa, India. In 2011, she started her PhD studies at UNIS and the UiT The Arctic University of Norway, in the field of Arctic paleoceanography. The study was funded by the Research Council of Norway. She was also actively participating in the Research School for Climate Dynamics administered by the University of Bergen.