Hydroclimate modulation of central-eastern Mexico by the North Atlantic subtropical high since the little ice age

Abstract

We reconstructed the hydroclimate of central-eastern Mexico over the last 700 common era (CE) based on inferences from multi-proxies from a stalagmite (K-Inc) collected at Karmidas cave, eastern México. Projections on hydroclimate variability in Mexico raise concerns about possible future occurrences of severe droughts and seasonal water balance fluctuations related to increased global temperatures caused by anthropogenic climate change (Murray-Tortarolo, 2021). The eastern region influences the production and supply of food to Mexico. Simulations of past climates, validated by paleoclimate records, yield valuable perspectives on climate change and enhance our understanding of future projections. However, the paucity of paleoclimatic records hinders understanding past hydroclimatic variations and their climatic mechanisms in eastern Mexico. Our record covers the Little Ice Age (LIA) through the Historical Interval (HI), a crucial period for understanding the climate repercussions spanning the transition from Earth's climatic history to the post-industrial era. The reduced intensity of the North Atlantic Subtropical High (NASH) during the LIA enabled a prominent negative phase of NAO-like variability from 1600 CE until the end of LIA. Consequently, preferent meridional airflow within the continent fosters the encounter of moisture-laden intrusions with the increased frequency of cold surges as the occurrence of frontal rain in eastern Mexico, impairing the amount effect on the K-Inc δ¹⁸O record. However, after the artificial opening of the cave in 1910 CE, the δ¹⁸O records of K-Inc began to exhibit a ∼20-year oscillatory periodicity. In this context, the trace elements of K-Inc help elucidate the climatic conditions that governed the precipitation regime during the investigated period. The visual alignment between the zonal sea surface temperature (SST) variability in the eastern equatorial Pacific (EEP) and the trace elements (Sr/Ca and Ba/Ca) of K-Inc reveals their relationship. Warm zonal SST in the EEP appears to be associated with changes in the length of the winter and summer seasons in eastern Mexico during the LIA. In contrast, over the HI, the trace elements of K-Inc show an anti-phase response to Warm zonal SST in the EEP, denoting wetter climate conditions at the vicinities of Karmidas Cave. This configuration led to questioning the influence of SST zonal variability in the EEP during the HI, which was probably masked by more relevant climate forcing. Our findings enabled us to draw climate scenarios by addressing the main climate drivers in our records.