![]() There is some uncertainty in climate models about the effect of climate change on rainfall at local and regional scales. In contrast, research suggests human-caused climate change is now playing a more important role in amplifying drought conditions, as rising global temperatures increase evaporation. For example, decades-long La Niña conditions have been linked to medieval droughts in North and South America. Historically, droughts have been defined by rainfall deficits, and these deficits can be largely attributed to complex interactions between oceans and the atmosphere over a long time. To look at previous occurrences of megadroughts, we consolidated findings drawn from such datasets and a range of other long-term records. Scientists can gauge local, yearly climate further back in time, by deciphering clues written in tree rings, corals, and buried ice (known as ice cores), among other archives. In Australia, they cover only the last 120 years or so. Instrumental records only go back so far. Unless we incorporate the full potential of Australian drought into our planning, management and design, their impacts on society and the environment will likely worsen in coming decades. They’ve dealt profound damage to agriculture and water supplies, increased fire risk, and have even contributed to toppling civilisations. We show megadroughts have occurred several times across every inhabited continent over the last two millennia. Megadroughts can also be shorter periods of very extreme conditions. Megadroughts can last multiple decades – or even centuries – with occasional wet years offering only brief relief. These are called “megadroughts”, and they’re likely to occur again in coming decades. But our new research finds over the last 1,000 years, Australia has suffered longer, larger and more severe droughts than those recorded over the last century. Most Australians have known drought in their lifetimes, and have memories of cracked earth and empty streams, paddocks of dust and stories of city reservoirs with only a few weeks’ storage. The name Hohokam means “those who have gone” in the Pima language.This article by Professor Pauline Grierson from the School of Biological Sciences at The University of Western Australia and Director, West Australian Biogeochemistry Centre, and Adjunct Research Fellow Alison O'Donnell from the School of Biological Sciences at The University of Western Australia, was originally published in The Conversation on October 6, 2022. The people of two modern tribes-the Pima and the Tohono O’odham-are probably their descendants. No one knows why they left or where they went. By about 1100 the neighboring Ancestral Pueblo had taught the Hohokam how to build homes from bricks made of adobe (sun-baked clay).ĭuring the early 1400s the Hohokam abandoned their villages. They made these houses by digging a shallow pit and covering it with a dome of wood and mud. The largest Hohokam settlement was located near what is now Phoenix, Arizona. They built wide canals from the Gila and Salt rivers to their fields so they would have enough water for farming. The soil where they lived was dry and sandy. They also grew cotton, which they wove into cloth. They grew corn, beans, pumpkins, and squash. The Hohokam got most of their food from farming. ![]() The Hohokam people lived in what is now Arizona from about 300 bce to about 1400 ce. ![]() The Hohokam culture was one of the first great Native American civilizations in what is now the United States. ![]()
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