Chapter 5 - Ocean circulation in high northern latitudes and its influence on Arctic climate through the ages

Abstract

High northern latitude climates, including those of the Arctic, have been responding to various forces, including plate movements, resulting in the opening up of the seaways and changes in paleobathymetry, resulting in changes to ocean circulations, greenhouse gas concentrations, and orbital parameters. During the Eocene times, the high northern latitude climates were also affected by the establishment of the Antarctic Circumpolar Current, established due to the opening of the Drake Passage and Tasmanian Seaway. The Atlantic Meridional Overturning Circulation (AMOC) and associated “conveyor belt” have been primary factors in poleward transport of heat from the tropics. Initiation of the AMOC or its precursor, the North Component Waters, has been attributed to the subsidence of the Greenland–Scotland Ridge and opening of the Fram Strait. Artifacts of Northern Hemisphere Glaciations (NHGs) are found in oceanic sediments in the form of ice-rafted debris as old as 44Ma coeval with initiation of the Antarctic glaciation. However, the permanent ice-sheet formation and NHG lag behind the Antarctic by ~ 30 million years. Various hypotheses have been put forward to explain the development of a permanent ice sheet in Greenland. These include freshening of the Arctic by Siberian rivers and consequent development of sea ice and increased albedo, closing of the Central American Seaway, strengthening of the Gulf Stream, and increased supply of moisture to the high northern latitudes. This chapter discusses various aspects of high northern latitude climate and the role of ocean circulation through the ages.