Exploring the long-term Cenozoic Arctic Ocean climate history: a challenge within the International Ocean Discovery Program (IODP)

Abstract

The global climate evolution during Cenozoic times is characterized by the transformation from warm Paleogene oceans with low latitudinal and bathymetric thermal gradients into the more recent modes of circulation characterized by strong thermal gradients, oceanic fronts, cold deep oceans, and cold high-latitude surface waters. Our understanding of this long-term Cenozoic climate history is mainly based on the continuous and high-resolution records from the low and mid-latitudes, whereas records from the high latitudes, especially the high northern latitudes, are strongly limited. From the central Arctic Ocean, information is restricted to sedimentary sections recovered on Lomonosov Ridge during the single scientific drilling campaign of the Integrated Ocean Drilling Program (IODP) in 2004—the “Arctic Coring Expedition (ACEX).” By studying the unique ACEX sequence, a large number of scientific discoveries that describe previously unknown Arctic paleoenvironments have been obtained during the last decade. However, major key questions dealing with the Cenozoic climate history of the Arctic Ocean on its course from Greenhouse to Icehouse conditions remain unanswered. In this review paper, we present (1) the main highlights of the ACEX expedition and (2) why there is a need for further scientific Arctic drilling together with the plan, objectives and strategy for a drilling campaign on Lomonosov Ridge (“ACEX2”). ACEX2 is scheduled for 2018 as a mission-specific platform approach within the new International Ocean Discovery Program (IODP).