The effects of the 8.2 ka event on the ITCZ in the tropical Atlantic

• Main Authors: Burger, Matthew, Hauser, Rachel, Morrill, Carrie, Wagner, Amy, Behler, Tom, Pauzauskie, Dana
• Format: Text
• Language: unknown
• Published: University Corporation For Atmospheric Research (UCAR) 2010
• Subjects: Greenland; Greenland ice cores; Labrador Sea; North Atlantic
• Online Access: https://dx.doi.org/10.5065/9bjj-7t73; https://opensky.ucar.edu/islandora/object/manuscripts:617

The 8.2 ka event, which occurred 8200 years before present, was a period of abrupt cooling that is recorded in multiple proxy records across the Northern Hemisphere. During this event, a cooling of 3.3°C ± 1.1°C, was estimated from Greenland ice cores and lasted about 150 years. Prior to the 8.2 ka event, the climate of the northern latitudes of the North Atlantic was similar to that of today. It is hypothesized that the 8.2 ka event was caused by release of fresh water from the proglacial Lake Agassiz into the Labrador Sea and North Atlantic Ocean. This fresh water flowed into the main subduction area of the North Atlantic. Density differences between the fresh and saline waters caused the thermohaline circulation to slow down, resulting in cooler surface temperatures over Greenland. While much of the proxy evidence for the 8.2 ka event is from the region surrounding the North Atlantic basin, recent evidence studies suggest impacts from the event extended beyond this region. This paper will consider the effects of the 8.2 ka event on the Intertropical Convergence Zone (ITCZ). Published studies on lake and ocean sediment cores and cave speleothems were considered. In addition, these proxy data were compared to NCAR CCSM3 model simulations of the 8.2 ka event to assess model accuracy. Study results indicate a southward shift of the ITCZ around 8.2 ka. The comparison between the 8.2 ka climate model simulations and the proxy data largely agree with model results, diverging most from the proxy data from the equator.