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US megadrought could upend life as we know it – just look to history

We don’t know exactly how the current megadrought in south-western North America will end, but there are examples to learn from throughout history  

Environment 17 November 2022

Aerial view of ancient Maya city Chichen Itza

Ruins of the ancient Maya city Chichen Itza

Shutterstock/Aleksandr Medvedkov

Around the world, severe droughts are disrupting life for millions of people. In south-western North America and the Pacific coast of South America, worst-in-a-millennium megadroughts have created a slow-moving disaster, as reservoir levels decline and whole regions prepare to make unprecedented cuts to make up the shortfall.

In the Horn of Africa, the worst drought in 40 years has put more than 7 million people at risk of famine. In Europe and China, drought and heat have made rivers impassable and tanked energy output at dams and nuclear plants.

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Global warming has made such droughts more severe and frequent in many places, but these exceptionally bad droughts – or megadroughts – are not only a modern phenomenon. According to a recent review, megadroughts have occurred on every continent except Antarctica over the past 2000 years.

A look at some of the worst droughts of the past can help us to prepare for the megadroughts of the future. Below, explore how megadroughts have changed the landscape and altered human societies for the last two millennia.

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