Drought
Megadrought Explained: Long-Term Dry Periods, Tree Rings, Reservoirs, and Climate
What a megadrought is, how scientists study long droughts, and why reservoirs, groundwater, snowpack, and heat matter.
Quick answer: A megadrought is an unusually long and severe drought lasting decades or longer across a broad region.
Long view
Scientists use tree rings, lake sediments, historical records, and modern observations to understand past droughts.
Instrument records alone may be too short for the full picture.
Water systems
Long drought affects reservoirs, groundwater, rivers, ecosystems, agriculture, and cities.
Heat can intensify drought by increasing evaporation and water demand.
Planning
Megadrought risk is about water management, land use, climate, and resilience.
One wet winter may not erase deep deficits.