ENSO-like forcing over the Sea Surface Temperature and partial pressure of carbon dioxide (pCO2) outgassing during the last 80Ky, off northern Chile (27.5ºS).

Past changes in SST and productivity in the eastern South Pacific have commonly been explained in terms of changes in the intensity of upwelling-favorable winds, and availability of nutrients, induced mainly by latitudinal shifts of the Southern Hemisphere westerly wind system together with changes in the location and intensification of the Antarctic Circumpolar Current (ACC). However, recently studies suggest an equatorial forcing such as ENSO-like. We used alkenone isotopic composition and concentration to estimate paleo- pCO2 and UK'37-SST in a sediment core collected off northern Chile (core GeoB 3375-1; 27º28'S, 71º15'W; 1947m depth; Age-time: 10-80 Kyr BP). Similar patterns between our record and others located north and south part of 27.5ºS, reveal that, our study area was strongly driven by atmospheric and oceanographic circulation patterns, such as: the Southern Westerlies and ACC for the south part, and ENSO-like cycles for the north. Thus, ~27ºS of latitude, could be considered as a northern boundary of the southern Westerlies and ACC and a southern boundary of ENSO-like cycle influence, respectively. The sea surface pCO2 was higher than atmospheric CO2, thus northern Chile could be considered as a permanent upwelling source of CO2 to the atmosphere. Although, the area exhibits a high primary production, this not plays an important role in the uptake of CO2.