# Controls on the southwest USA hydroclimate over the last six glacial-interglacial cycles

## TL;DR

A 580,000-year-old cave record from Nevada shows how temperature, ice sheets, and summer sunlight shaped the southwest U.S. climate over six glacial cycles.

## Contribution

A new absolute-dated isotope record from Devils Hole cave reveals climate drivers in the southern Great Basin over the last six glacial-interglacial cycles.

## Key findings

- Temperature-related mechanisms are a primary driver of δ18O variability in the region.
- Vegetation density in southern Nevada is primarily forced by Northern Hemisphere summer intensity.
- Primary productivity declines rapidly during warm interglacial periods with reduced groundwater recharge.

## Abstract

The Great Basin in the southwest United States experienced major hydroclimate shifts throughout the Quaternary. Understanding the drivers behind these past changes has become increasingly important for improving future climate projections. Here, we present an absolute-dated δ18O and δ13C record from Devils Hole cave 2 (southern Nevada) that reveals climate and environmental changes in the southern Great Basin over the last 580,000 years. Water isotope-enabled Earth system simulations and phasing analysis show that temperature-related mechanisms are a primary driver of δ18O variability, with additional drivers stemming from processes linked to North American ice sheets. Vegetation density in the highlands of southern Nevada is primarily forced by Northern Hemisphere summer intensity. A rapid decline in primary productivity occurs during warm interglacial periods when local groundwater recharge declines to <50% above modern. Our study sheds new light on the relationship between temperature, moisture balance, and vegetation over the last six glacial-interglacial cycles.

A 580,000-year cave record from southern Nevada reveals how temperature, ice sheets, and summer insolation influenced the southwest United States’ unique climate history over the last six glacial-interglacial cycles.