water scarcity

Oases and desertification

May 21, 2024 By EarthWise Leave a Comment

Oases are important sources of water for people, plants, and animals in the world’s desert areas. In fact, oases sustain 10% of the world’s population despite taking up only about 1.5% of land area. They form when groundwater flows and settles into low-lying areas or when surface meltwater flows down from nearby mountains and pools.

New research from the Chinese Academy of Sciences has found that oases added 85,000 square miles of new area from 1995 to 2020, mostly from artificial expansion projects, but over the same period lost 52,000 square miles from desertification and water scarcity. The net gain of 33,000 square miles is not considered to be sustainable given that it was mostly due to artificial causes. The oasis expansion projects were in Asia but losses due to desertification were also mostly in Asia.

Today, oases are found in 37 countries. Increases in oases mostly come from people intentionally converting desert land into oases using runoff water and groundwater pumping, creating grasslands and croplands. This mostly has taken place in China.

Human over-exploitation of dwindling groundwater can limit the sustainability of oases as can the long-term loss of glaciers.

The study highlighted ways to sustain healthy oases, including suggestions for improving water resource management, promoting sustainable land use and management, and encouraging water conservation and efficient water use. As the climate continues to change, these efforts will be increasingly important for a significant portion of the world’s population.

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World’s Oases Threatened By Desertification, Even As Humans Expand Them

Photo, posted August 3, 2008, courtesy of Paul Williams via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Rewilding The American West | Earth Wise

September 14, 2022 By EarthWise Leave a Comment

Oregon State University scientists have proposed a series of management changes for western federal lands aimed at re-establishing ecosystems there. Their proposal would result in more gray wolves and beavers in nearly 200,000 square miles of federal lands in 11 states.

In each of those states, the researchers identified areas containing prime wolf habitat. Gray wolves were hunted to near extinction in the West but have been gradually reintroduced in some areas starting in the 1990s. Wolf restoration offers significant ecological benefits by helping to naturally control the population of grazing animals such as elk. This in turn facilitates the regrowth of vegetation species such as aspen, which ultimately supports diverse plant and animal communities.

Beaver populations, which used to be robust across the West, declined roughly 90% after settler colonialism and are now nonexistent in many areas. By felling trees and shrubs and constructing dams, beavers enrich fish habitat, increase water and settlement retention, maintain water flows during droughts, and increase carbon sequestration.

According to the researchers, the biggest threat to these western lands is livestock grazing, which has degraded ecosystems to a great extent. They recommend the removal of grazing on about 30% of the federal lands being used for that purpose and instead would have rewilding efforts go on.

The American West is going through a period of converging crises including extended drought and water scarcity, extreme heat waves, massive fires, and loss of biodiversity. Rewilding is a way to reestablish long-standing ecosystems.

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More wolves, beavers needed as part of improving western United States habitats, scientists say

Photo, posted October 1, 2020, courtesy of Tina DaPuglet via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

More Mega-Droughts | Earth Wise

December 2, 2020 By EarthWise Leave a Comment

According to a new report led by researchers from the University of Queensland in Australia, mega-droughts are expected to increase as global temperatures rise with the progression of climate change. While mega-droughts have no strict scientific definition, most studies – including this one – define them as prolonged droughts lasting two decades or longer.

The research team analyzed geological records from the Eemian Period – 129,000 to 116,000 years ago – to create a model of what to expect over the next 20-50 years. The Eemian Period is the most recent in Earth’s history when global temperatures were similar – or maybe even slightly warmer – than they are today.

By analyzing the climate during this period, the research team found that the world will likely experience increased water scarcity, reduced winter snow cover, more frequent wildfires and wind erosion as a result of global warming.

In the report, which was recently issued by the University of Queensland, the researchers collaborated with the New South Wales Parks and Wildlife Service to identify stalagmites in the northern section of Kosciuszko National Park. They were able to study small samples of calcium carbonate powder contained in the cave stalagmites, allowing them to identify periods of reduced precipitation during the Eemian Period.

Historically, mega-droughts have been associated with mass exoduses of people from the affected areas. In fact, mega-droughts are suspected of contributing to the collapse of several pre-industrial civilizations across Southeast Asia and the Americas.

If humans continue to warm the planet, the researchers say more mega-droughts will be in our future.

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Expect more mega-droughts

Photo, posted March 28, 2014, courtesy of Marufish via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Solar-Powered Desalination | Earth Wise

March 20, 2020 By EarthWise Leave a Comment

About 1% of the world’s population is dependent on desalinated water to meet daily needs, but water scarcity is a growing problem that experts believe will affect 14% of the world’s population within the next five years.

Desalination takes much more energy than, for example, transporting fresh water over large distances. In general, desalination costs are much higher than those associated with fresh water, but beyond costs, freshwater is simply not always available.

Researchers at MIT and Shanghai Jiao Tong University in China have developed a completely passive solar-powered desalination system that could provide more than 1.5 gallons of fresh drinking water per hour for every square meter of solar collecting area. Such a system could provide an efficient, low-cost water source for coastal areas that are off the grid.

The system uses multiple layers of flat solar evaporators and condensers topped with transparent aerogel insulation. The key to its efficiency is the way it uses each of its multiple stages to desalinate water. At each stage, heat released by the previous stage is harnessed instead of wasted. The proof-of-concept device, which was tested on an MIT building rooftop, produced more than twice as much water as the record amount produced by any previous passive solar-powered desalination system.

The researchers plan further experiments aimed at optimizing the choice of materials and configurations and to test the system under realistic conditions. The hope is to have a technology that can play a role in alleviating water scarcity in parts of the world where electricity is scarce, but seawater and sunlight are abundant.

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