Nevada Cave Reveals an Ancient Climate Paradox

To better predict our planet's future climate, scientists are delving into its deep past. A new study has unlocked 580,000 years of environmental history from the American southwest by analysing chemical signatures, or isotopes, preserved in a Nevada cave.

The research, which combined the cave record with sophisticated Earth system modelling, confirms that temperature and the behaviour of the vast North American ice sheets were the primary forces shaping the region's climate over six major glacial-interglacial cycles. However, the team uncovered a surprising relationship between warmth and life.

Vegetation density was found to be driven mainly by the intensity of summer in the Northern Hemisphere. Paradoxically, during the warmest "interglacial" periods, plant productivity actually plummeted. This occurred because local groundwater recharge—the refilling of underground water stores—declined sharply, starving the ecosystem of essential moisture despite the favourable temperatures. This work sheds new light on the delicate balance between temperature, water, and life.