Uncovering Spatial Patterns and Drivers of Droughts in NE Mexico with a New Stalagmite Record of the Last Millennium

Abstract:

Hydroclimate in Northeast Mexico is likely influenced by both Atlantic and Pacific ocean-atmosphere modes that are known to control droughts throughout the Americas. However, the lack of records from Northern Mexico have limited our understanding of the spatial distribution and magnitude of natural precipitation in the region. To address this, we have developed the first high-resolution (~2 yr), multi-proxy speleothem record from Tamaulipas, Mexico. U-series and radiocarbon dating combined with fluorescence laminae layer-counting confirm stalagmite CB4 was actively growing when collected and spans the last millennium. This record is a robust reconstruction of hydroclimate as indicated by the agreement amongst multiple geochemical proxies for precipitation amount (d¹⁸O) and local water balance (d¹³C, Mg/Ca), further informed by modern cave measurements and precipitation isotope data. Through comparison to Pacific and Atlantic sea surface temperatures and pressures, we explore drivers of droughts in NE Mexico. Merging our record with regional tree-ring records and speleothem records from southern Mexico, we discuss the dichotomous response of precipitation on multi-decadal timescales between northern and southern Mexico over the last 1,000 years.