Oasis of the world threatened by desertification

Oases are important habitats and water sources in arid regions and are home to 10% of the world's population, although they cover approximately 1,5% of the Earth's surface. However, in many places, climate change and human activity are threatening the fragile existence of oases.

Many oases around the world have been artificially expanded by humans, but this water-intensive practice is often unsustainable. Desertification has led to the loss of approximately 52.000 square miles of oases, and many more are likely to disappear.

A new study shows how the number of oases around the world has waxed and waned over the past 25 years as water availability changed and desertification encroached on these swampy paradises.

"Although the scientific community has always emphasized the importance of oases, there is still no clear map of their distribution."said Dongwei Gui, a geologist at the Chinese Academy of Sciences who led the study on their world."Oasis research has both theoretical and practical implications for achieving the United Nations Sustainable Development Goals and promoting sustainable development in drylands".

In figures, the oases of the world from 1995 to 2020:

The study found that between 1995 and 2020, the area of ​​oases worldwide increased by more than 220.149 square kilometers (85.000 square miles), largely due to deliberate oasis expansion projects in Asia. However, desertification caused the loss of 134.300 square kilometers (51.854 square miles) of oases during the same period, mainly in Asia, resulting in an increase of 86.500 square kilometers (about 33.400 square miles) during the study period.

  • The oases gained 85.000 square miles, mainly thanks to artificial expansion projects.
  • The oases lost 52.000 square miles to desertification and water scarcity.
  • The oases gained a net area of ​​approximately 33.400 square miles, but that largely artificial growth is not sustainable.

The results highlight the risks that climate change and other human-induced stressors pose to these protected wetland areas and can form the basis for water management and sustainable development in arid regions. The results of the research were published in the journal Earth's Future, a magazine specialized in interdisciplinary research on the past, present and future of our planet and its inhabitants.

The birth and death of the world's oases

The world's oases are an important source of water for people, plants and animals in arid regions and provide much of the productivity and life in deserts.

They form when groundwater moves and settles in low-lying areas or when surface meltwater flows from nearby mountain ranges and reservoirs. The existence of the oasis depends largely on the availability of a reliable source of water other than rain.

Today, the world's oases are distributed in 37 countries, 77% of which are located in Asia and 13% in Australia.

Gui and his colleagues want to understand the global distribution and dynamic changes of the world's oases and see how they respond to changing environments such as climate change, water resources and human activity. Using data from Land Cover Product of the European Space Agency Climate Change Initiative, the team classified the earth's surface into seven types: forest, grassland, shrubland, cropland, water, city and desert.

Scientists used satellite data to search for lush vegetation in dry regions, identify oases and track changes over 25 years. Changes in the greenness of vegetation indicate changes in land use and the health of oases, which can be affected by both human activity and climate change.

oasis of the world

They also examined changes in land surface type to determine land use conversion. Scientists have found that the global oasis area has increased by 220.800 square kilometers (85.251 square miles) in 25 years.

Much of this growth has occurred because humans deliberately converted desert lands into oases, using wastewater and pumping groundwater to create pastures and cropland. Gui said growth was concentrated in China, where management efforts accounted for more than 60% of growth. For example, more than 95% of the population of China's Xinjiang Uyghur Autonomous Region lives in an oasis, promoting the preservation and expansion of the 16.700-square-kilometer (6.448-square-mile) oasis, Gui said.

Despite human efforts to expand oases, desertification has contributed to their loss. Scientists have discovered that more than 25 square kilometers of oasis land have been lost worldwide in the last 134.000 years. Scientists estimate that the changes at the oasis have directly affected about 34 million people worldwide.

Overall, between gains and losses, the net gain of the world's oases was 86.500 square kilometers (33.397 square miles) between 1995 and 2020, but most of the gain was due to the artificial expansion of oases, which can not be sustainable in the future.

Long-term sustainability of the oasis

The study outlines ways to maintain healthy oases, including recommendations to improve water management, promote sustainable land use and management, and encourage conservation and efficient use of water. Gui said these efforts are especially important given current climate change.

Human overexploitation of increasingly scarce groundwater resources could limit the durability of oases and lead to the long-term disappearance of the oases. glaciers. While warmer temperatures increase ice melting, temporarily increasing the water supply in the oases, "As glaciers gradually disappear, the amount of meltwater will eventually decrease, causing oases to shrink again"Gui said

Gui added that international cooperation is important to ensure the sustainability of the world's oasis. “Due to the unique oasis formation mechanism, a river basin often has many oases in different countries, making cross-border cooperation the key to solving water scarcity and promoting sustainable development.".

Ecoportal.net

With information of: https://www.eurekalert.org/