Australia: The Land Where Time Began

A biography of the Australian continent 

ENSO affected by Sothern High Latitude Cooling During the Medieval Period

In this study the authors¹ carried out a high-resolution multiproxy study on a marine record from the SE Pacific off the coast of southern South America to reconstruct regional environmental changes that occurred over the last 2,200 years, and their relation to global climate, to the El Niño/Southern Oscillation (ENSO) phenomenon in particular. It is suggested by their results that the position of the zonal systems, i.e. the belt of Southern Westerly Wind and the Antarctic Circumpolar Current that between 1,300 and 750 BP, shifted to the north in a sustained manner. A causal link between ENSO and the displacement of the zonal systems that has been proposed is suggested by synchrony of latitudinal shift with Antarctic cooling and reduced ENSO activity that has been found across South America in several marine and terrestrial archives. The authors¹ suggest that by steepening the gradient of the hemispheric and tropical Pacific zonal sea surface temperature this shift may have acted as a positive feedback to conditions that were more like a La Niña from 1,300-750 BP. It is also suggested by this scenario that prior to 1,300 BP and after 750 BP there were different boundary conditions for ENSO.

Sources & Further reading

1. Mohtadi, Mahyar, Oscar E. Romero, Jérôme Kaiser, and Dierk Hebbeln. "Cooling of the Southern High Latitudes During the Medieval Period and Its Effect on Enso." Quaternary Science Reviews 26, no. 7–8 (4// 2007): 1055-66.