NW Iberia speleothems, a bridge to understand past high latitude to tropical teleconnections

Abstract:

Superimposed on the strong regional tropical insolation forcing, processes in the high latitude North Atlantic have long been known to have manifestations in tropical hydroclimate, as revealed by climate models and by Asian speleothem oxygen isotope records. However, the scarcity of absolute dated records from the high latitude North Atlantic has made it difficult to test the specific drivers of this teleconnection and if the sensitivity of the teleconnection has varied with background climate state.

Here we present a new NW Iberia speleothem record of glacial meltwater release into the Eastern North Atlantic and regional air temperature, including Termination I, and II and large portions of MIS6-5. NW Iberia coastal cave speleothem oxygen isotopic ratio is dominantly controlled by the oxygen isotopic ratio of the adjacent eastern North Atlantic ocean. This permits not only of precise tuning of adjacent marine sediment records, but also resolution of the temperature and amount components from other speleothem oxygen isotope records farther inland in Europe. Thus unlike other North Atlantic records which have tuned chronology to Asian speleothems based on assumptions of stationary teleconnections, the new NW Iberia record now provides an independent comparison.

We therefore investigate the impact of changes in meltwater flux, sea ice coverage, and northern European temperatures on the hydroclimate record in Asian speleothem oxygen isotopes, interpreted to reflect the duration of the Meiyu and midsummer stages and onset of ITCZ migration. We find one of the strongest correlations between North Atlantic sea ice coverage and the Asian speleothem oxygen isotopic record. We discuss the evidence for links between NH Westerly winds and the impact of ITCZ precipitation in the Asian monsoon region.