Tracking regional and global teleconnections recorded by western North American speleothem records

Abstract

Abstract Speleothem proxy records are useful for interrogating past climates in the low and mid-latitudes given their ability to provide continuous, high-resolution, and long-lived records that can be dated with high precision. Several speleothem oxygen isotope records from western North America have recently been developed that highlight the importance of this archive in documenting past changes in atmospheric circulation. Taken individually, these records hint at teleconnections between western North American hydroclimate and climate changes in the high northern latitudes and tropics. However, there has been no systematic investigation of global climate teleconnections to this region that draws upon the body of North American speleothem records as a whole. Here we review the dominant controls on precipitation oxygen isotopes across the region, and conduct statistical comparisons and network visualizations of high-resolution speleothem oxygen isotope records from western North America to investigate the regional response to pronounced climate changes of the last deglaciation and to determine the pattern of global teleconnections to this region. We find that most western North American speleothem oxygen isotope records demonstrate a robust and consistent response to the events of the last deglaciation, despite differing controls on the oxygen isotope ratio of precipitation across the region. One record that receives a strong influence from the Gulf of Mexico exhibits a contrasting pattern in oxygen isotopes relative to most of the other records, which are dominated by westerly storms generated in the Pacific. During the studied interval, major shifts in Western North American speleothem records appear broadly synchronous at least within the uncertainty of age models. We also find strong statistical linkages between western North American speleothem records and speleothem records of Asian monsoon variability and other records from regions directly influenced by movement of the Intertropical Convergence Zone, demonstrating that nearly synchronous changes in atmospheric circulation measurably altered precipitation dynamics in these regions during the last deglaciation. Further multi-proxy investigations are needed to determine how such changes in atmospheric circulation recorded by speleothem oxygen isotope ratios influenced precipitation amounts in drought-prone western North America.