An independently corroborated, diatom-inferred record of longterm drought cycles occurring over the last two millennia in New Mexico, USA

We investigated late Holocene (2000 YBP to present) drought in northern New Mexico, USA, using diatom valves sampled from a lake sediment core. Diatoms were analyzed with a combination of multivariate ordination and time series analysis to identify significant changes in community dynamics and corresponding significant bifurcations between periods of increased and decreased precipitation. This diatom-inferred precipitation regime was statistically corroborated against an independently derived tree ring record of precipitation in northern New Mexico. Also, both the tree ring and diatom records were tested for concordance with indirect radiocarbon solar intensity data and were both significantly cross-correlated with solar intensity. Periods of drought aligned with periods of decreased solar intensity during ~1400-1000 and ~600-200 YBP; periods of increased solar activity aligned with periods of increased precipitation during ~1000-600 YBP and ~200 YBP to present day. These results suggest that longer-term drought regimes in northern New Mexico may have been modulated by solar activity.