Global Intermediate Water Evolution during the Last Deglaciation in C-iTRACE

Abstract:

During the last deglaciation (21ka to 11ka), Earth’s climate experienced strong—and sometimes abrupt—variations, resulting in major changes in global temperature, sea level, and ocean circulation. Although multiple proxy records have significantly improved our understanding of climate during this period, many questions remain regarding ocean circulation evolution, particularly of deep and intermediate waters. Model simulations such as TraCE-21ka have attempted to remedy this, but typically do not incorporate carbon isotopes and other relevant geotracers that are directly comparable to proxy records. Here we use a 3˚ ocean-only simulation with the Community Earth System Model (known as the C-iTRACE simulation) with carbon isotopes, neodymium isotopes, and water isotopes as well as a marine carbon cycle to study the evolution of global ocean intermediate waters over the past 21,000 years. We examine the model’s zonal mean intermediate water evolution in the three major ocean basins (the Atlantic, Pacific, and Indian) using δ¹³C and Δ¹⁴C. We also directly compare proxy records at specific locations to the same locations within the model in order to understand intra-basin variations within the proxies themselves.