Climate change is set to unleash a series of decades-long “megadroughts” this century, according to research to be published this week.
Experts warn the droughts could be even more severe than the prolonged water shortage currently afflicting California, where residents have resorted to stealing from fire hydrants amid mass crop failures and regular wildfires.
Megadroughts – which are generally defined as lasting 35 years or more – will become considerably more frequent as global warming increases temperatures and reduces rainfall in regions already susceptible, warns Cornell University’s Dr Toby Ault, the author of the new report.
Megadroughts are also likely to be hotter and last longer than in the past, he claimed. His peer-reviewed research – to be published in the American Meterological Society’s Journal of Climate – is the first to scientifically establish that climate change exacerbates the threat.
In pictures: Changing climate around the world
In pictures: Changing climate around the world
Calved icebergs from the nearby Twin Glaciers are seen floating on the water in Qaqortoq, Greenland
Oroumieh, one of the biggest saltwater lakes on Earth, has shrunk more than 80 percent to 1,000 square kilometers in the past decade. It shrinks mainly because of climate change, expanded irrigation for surrounding farms and the damming of rivers that feed the body of water
A boat navigates among calved icebergs from the nearby Twin Glaciers in Qaqortoq, Greenland. Boats are a crucial mode of transportation in the country that has few roads. As cities like Miami, New York and other vulnerable spots around the world strategize about how to respond to climate change, many Greenlanders simply do what theyve always done: adapt. 'Were used to change, said Greenlander Pilu Neilsen. 'We learn to adapt to whatever comes. If all the glaciers melt, well just get more land
The Svalbard Global Seed Vault is seen after being inaugurated in Longyearbyen, Norway. The 'doomsday' seed vault built to protect millions of food crops from climate change, wars and natural disasters opened deep within an Arctic mountain in the remote Norwegian archipelago of Svalbard
A technician preparing to drain a vast underground lake at the Tete Rousse glacier on the Mont Blanc Alpine mountain, to avert a potentially disatrous flood. Some 65,000 cubic metres (2.3 million cubic feet) of water have gathered in a cavity, dangerously raising the pressure beneath the mountain, a favourite spot for holiday makers in Saint-Gervais-les-Bains
Cracked mud is picture at sunrise in the dried shores of Lake Gruyere affected by continuous drought near the western Switzerland village of Avry-devant-Pont. A leading climate scientist warned that Europe should take action over increasing drought and floods, stressing that some climate change trends were clear despite variations in predictions
Cattle graze on grassland that remains dry and brown at the height of the rainy season in south of Bakersfield, California. Its third straight year of unprecedented drought, California is experiencing its driest year on record, dating back 119 years, and dating back as far as 500 years, according to some scientists who study tree rings
An aerial view shows tents of flood-displaced people surrounded by water in southern Sehwan town. United Nations Framework Convention on Climate Change (UNFCCC) executive secretary Christiana Figueres met with people displaced by last year's devastating floods. Catastrophic monsoon rains that swept through the country in 2010 and affected some 20 million people, destroyed 1.7 million homes and damaged 5.4 million acres of arable land
An aerial view of flooding in North Wagga Wagga. Climate change is amplifying risks from drought, floods, storm and rising seas, threatening all countries but small island states, poor nations and arid regions in particular, UN experts warned
Damages caused by a landslide on the Pan-American highway near La Moramulca, 55 Km south of Tegucigalpa. International highways have been washed out, villages isolated and thousands of families have lost homes and crops in a region that the United Nations has classified as one of the most affected by climate change
A resident sprays water on a peatland fire in Pekanbaru district in Riau province on Indonesia's Sumatra island. Indonesia, an archipelago of 17,000 islands, is one of the world's biggest carbon emitters because of rampant deforestation. US Secretary of State John Kerry Sunday issued a clarion call for nations to do to more to combat climate change, calling it 'the world's largest weapon of mass destruction'
An excavator clearing a peatland forest area for a palm oil plantations in Trumon subdistrict, Aceh province, on Indonesia's Sumatra island. As Southeast Asia's largest economy grows rapidly, swathes of biodiverse forests across the archipelago of 17,000 islands have been cleared to make way for paper and palm oil plantations, as well as for mining and agriculture. The destruction has ravaged biodiversity, placing animals such as orangutans and Sumatran tigers in danger of extinction, while also leading to the release of vast amounts of climate change-causing carbon dioxide
Stagnant rain water with tannery waste make the Hazaribagh area in Old Dhaka as well as Buriganga River the most polluted. Each year during the seven-month long dry season between October and April the Buriganga River becomes totally stagnant with its upstream region drying up and becoming polluted from toxic waste from city industries
Waste water from Dhaka city drained to the River Buriganga contributes to its pollutions. On the World Water Day observed in 2007 under the theme Coping with Water Scarcity, under the leadership of the Food and Agriculture Organization of the United Nations, DrikNEWS explores some of the images of the river. UN-Water has identified coping with water scarcity as part of the strategic issues and priorities requiring joint UN action. The theme highlights the significance of cooperation and importance of an integrated approach to water resource management of water at international, national and local levels
Heavy smog has been lingering in northern and eastern parts of China, disturbing the traffic, worsening air pollution and forcing the closure of schools. China's Environment Ministry said it will send inspection teams to provinces and cities most seriously affected by smog to ensure rules on fighting air pollution are being enforced
“We can now explicitly add megadroughts to the list of risks that are being intensified by climate change. Without climate change there would be a 5 to 15 per cent risk of a megadrought in the south-west of the US this century. With it, the probability jumps to between 20 per cent and 50 per cent, with the southernmost part of the country particularly at risk,” Dr Ault told The Independent.
The threat megadroughts pose is so great they could decimate the world’s economy and food supply, inflicting a humanitarian crisis, experts warned.
“Global warming will make droughts evermore severe and devastating in the future. The south-west of the US, southern Europe, much of Africa, India, Australia and much of Central and South America could all have a drought that lasts decades,” said Jonathan T Overpeck, an environmental scientist at the University of Arizona.
Video: The truth about global water shortages
“It is feasible that continued global warming could lead to multiple regions experiencing a hot megadrought at the same time in the future. This could lead to global economic, food and humanitarian shocks,” Dr Overpeck added.
Megadroughts are defined more by their duration than their intensity. They have historically been associated with prolonged La Niña conditions, which create cooler than normal water temperatures in the tropical eastern Pacific Ocean. This reduces evaporation and, in turn, the amount of rainfall.
Megadroughts have occurred periodically around the world in the past few thousand years. In some cases they have caused civilisations to collapse, such as the ancient Puebloan native-American tribes in the south-west of the US – who abandoned their homes during a megadrought in the late 13th century – and the Khmer empire of Cambodia in the 14th century.
The fallout from future megadroughts will be even more severe because the global population is larger and the strain on water supplies is greater, warns Professor Park Williams of Columbia University in New York.
“Many of the already drought-prone parts of the planet will see megadroughts during this century that are far worse than anything those regions have seen in the past several thousand years at least.”
Prof Williams believes governments should pay some industry and communities to cut their water consumption.
While the UK is unlikely to suffer its own megadrought, Dr Overpeck warned that Britain could be hit by a megadrought elsewhere, especially in regions it relies on for food, or in zones prone to conflict.