Geometry.Net - Science: Desertification

Desertification - Wikipedia, The Free Encyclopedia
Encyclopedia article that describes the causes of desertification, and how it can be countered.
http://en.wikipedia.org/wiki/Desertification

Extractions: Jump to: navigation search For the labor union vitiation procedure, see NLRB election procedures#Decertification elections Ship stranded by the retreat of the Aral Sea Desertification is the degradation of land in arid semi arid and dry sub-humid areas resulting from various climatic variations, but primarily from human activities. Current desertification is taking place much faster worldwide than historically and usually arises from the demands of increased populations that settle on the land in order to grow crops and graze animals. A major impact of desertification is biodiversity loss and loss of productive capacity , for example, by transition from grassland dominated by perennial grasses to one dominated by perennial shrubs. In the southwestern deserts of the United States , semiarid ecosystems dominated by perennial bunchgrasses, including blue grama and black grama , have been replaced by shrublands dominated by creosotebush since the early 1900s. The change in vegetation is thought to have induced desertification in this region. In the Madagascar 's central highland plateau, 10% of the entire country has been lost to desertification due to
Desertification
Describes the prolems that desertification causes to humans, how it s monitored, and how we can fix it.
http://pubs.usgs.gov/gip/deserts/desertification/

Extractions: The Sahelian drought that began in 1968 was responsible for the deaths of between 100,000 and 250,000 people, the disruption of millions of lives, and the collapse of the agricultural bases of five countries (photograph by Daniel Stiles, UNEP). The world's great deserts were formed by natural processes interacting over long intervals of time. During most of these times, deserts have grown and shrunk independent of human activities. Paleodeserts, large sand seas now inactive because they are stabilized by vegetation, extend well beyond the present margins of core deserts, such as the Sahara. In some regions, deserts are separated sharply from surrounding, less arid areas by mountains and other contrasting landforms that reflect basic structural differences in the regional geology. In other areas, desert fringes form a gradual transition from a dry to a more humid environment, making it more difficult to define the desert border. These transition zones have very fragile, delicately balanced ecosystems. Desert fringes often are a mosaic of microclimates. Small hollows support vegetation that picks up heat from the hot winds and protects the land from the prevailing winds. After rainfall the vegetated areas are distinctly cooler than the surroundings. In these marginal areas, human activity may stress the ecosystem beyond its tolerance limit, resulting in degradation of the land. By pounding the soil with their hooves, livestock compact the substrate, increase the proportion of fine material, and reduce the percolation rate of the soil, thus encouraging erosion by wind and water. Grazing and the collection of firewood reduces or eliminates plants that help to bind the soil.
Desertification
Describes what causes desertification, and how we can stop it.
http://www.botany.uwc.ac.za/Envfacts/facts/desertification.htm

Extractions: Desertification is the process which turns productive into non- productive desert as a result of poor land-management. Desertification occurs mainly in semi-arid areas (average annual rainfall less than 600 mm) bordering on deserts. In the Sahel, (the semi-arid area south of the Sahara Desert), for example, the desert moved 100 km southwards between 1950 and 1975. WHAT CAUSES DESERTIFICATION? * Overgrazing is the major cause of desertification worldwide. Plants of semi-arid areas are adapted to being eaten by sparsely scattered, large, grazing mammals which move in response to the patchy rainfall common to these regions. Early human pastoralists living in semi-arid areas copied this natural system. They moved their small groups of domestic animals in response to food and water availability. Such regular stock movement prevented overgrazing of the fragile plant cover. In modern times, the use of fences has prevented domestic and wild animals from moving in response to food availability, and overgrazing has often resulted. However, when used correctly, fencing is a valuable tool of good veld management.
FAO Desertification Web Site
FAO website on the topic, with technical and scientific data and information available at FAO, plus internet links. Site available in Arabic, English,
http://www.fao.org/desertification/
Desertification: Scientific Facts On Desertification
This Digest is a faithful summary of the leading scientific consensus report produced in 2005 by the Millennium Ecosystem Assesment (MA) desertification
http://www.greenfacts.org/en/desertification/

Extractions: Context - Desertification is the persistent degradation of dryland ecosystems. It threatens the livelihoods of some of the poorest and most vulnerable populations on the planet. Desertification is largely caused by unsustainable use of scarce resources. What options exist to avoid or reverse desertification and its negative impacts? What is desertification? How are desertification and human well-being linked? Who is affected by desertification? What are the major causes of desertification? ... Conclusion: Main findings This Digest is a faithful summary of the leading scientific consensus report
UNCCD - United Nations Convention To Combat Desertification
The First Extraordinary session of the Conference of the Parties to the United Nations Conventions to Combat desertification (UNCCD) took place in the
http://www.unccd.int/main.php
BBC NEWS | Africa | UN Issues Desertification Warning
desertification represents the greatest environmental challenge of our times , the UN warns in a report.
http://news.bbc.co.uk/2/hi/africa/6247802.stm

Extractions: @import "/css/screen/shared/styles.css?v1"; @import '/css/screen/shared/toolbar_ifs.css'; @import "/css/screen/nol/styles.css?v2"; @import "/css/screen/nol/furniture.css"; @import "/css/screen/nol/promo.css"; @import "/css/screen/nol/programmes.css?v3"; @import "/css/screen/nol/business.css"; @import "/css/screen/nol/ifs.css"; @import "/css/screen/nol/in_pictures.css"; Home News Sport Radio ... Accessibility help One-Minute World News News Front Page Africa Americas Asia-Pacific ... Special Reports RELATED BBC SITES LANGUAGES Last Updated: Thursday, 28 June 2007, 10:49 GMT 11:49 UK E-mail this to a friend Printable version UN issues desertification warning Desertification could displace up to 50m people over the next decade Tens of millions of people could be driven from their homes by encroaching deserts, particularly in sub-Saharan Africa and Central Asia, a report says. The study by the United Nations University suggests climate change is making desertification "the greatest environmental challenge of our times".
Desertification
desertification in Minqin County will be primarily controlled in the near future. According to the planning, China will invest 4.749 billion yuan in
http://desertification.wordpress.com/

Extractions: All about desertification and poverty, agriculture and horticulture in the drylands Posted by: willem van cotthem Read at : http://www.seabuckthorn.net/index.php/?p=87. Heal the World: Desertification blog Jan 22nd, 2008 by Natalie Anne Lanoville As touched on in my recent post, Seabuckthorn holds back the desert on the windy plains of Asia desertification is a grave problem throughout the world, from traditionally arid, low-production areas to lush, productive greenbelts. Human activities (including redirection of surface water, siphoning of groundwater, intensive farming practices, clearcutting and many other factors) are implicated in much of this desert encroachment. There are committed, effective people and organisations working in isolation all over the world to combat this growing threat, but according to Dr Willem VAN COTTHEM, the owner and sole contributor to Desertification: All about desertification and poverty, agriculture and horticulture in the drylands , efforts to act, research and support activists have been hampered by a lack of centralised information. As he states on the About page of his blog, VAN COTTHEM (
Deserts And Desertification
More than 70% of earth is affected by desertification but it can be stopped.
http://www.didyouknow.cd/deserts.htm

Extractions: Did you know? Fascinating facts Animals Cartoons Countries ... Sitemap About 3,6 billion of the world's 5.2 billion hectares of useful dryland for agriculture has suffered erosion and soil degradation. In more than 100 countries, 1 billion of the 6 billion world population is affected by desertification, forcing people to leave their farms for jobs in the cities. Desertification is devouring more than 20,000 square miles of land worldwide every year. Desertification affects 74% of the land in North America. In Africa, more than 2.4 million acres of land (73% of its drylands) are affected by desertification. Desertification takes place in dryland areas where the earth is especially fragile, where rainfall is nil and the climate harsh. The result is the destruction of topsoil followed by loss of the land's ability to sustain crops, livestock or human activity. The economic impact is horrendous, with a loss of more than $40 billion per year in agricultural goods and an increase in agricultural prices. Climatic changes can trigger the desertification process, but human activities frequently are the proximate cause. Overcultivation exhausts the soil. Deforestation removes trees that hold the soil to the land. Overgrazing of livestock strips the land of grasses. According to a UN study, about 30% of earth's land - including the 70% of dryland - is affected by drought. Every day, about 33,000 people starve to death.
Desertification
An article that describes how global warming can lead to desertification.
http://www.ace.mmu.ac.uk/eae/Global_Warming/Older/Desertification.html

Extractions: Desertification One of the impacts which global warming may have on the surface of the Earth is to exacerbate the worldwide problem of desertification. A decrease in the total amount of rainfall in arid and semi-arid areas could increase the total area of drylands worldwide, and thus the total amount of land potentially at risk from desertification. Desertification was defined at the Rio Earth Summit in 1992 as "land degradation in arid, semi-arid and dry sub-humid areas resulting from various factors including climatic variations and human activities". Desertification involves the depletion of vegetation and soils. Land degradation occurs all over the world, but it is only referred to as desertification when it takes place in drylands. This is because these areas are especially prone to more permanent damage as different areas of degraded land spread and merge together to form desert-like conditions. Global warming brought about by increasing greenhouse gas levels in the atmosphere is expected to increase the variability of weather conditions and extreme events . Many dryland areas face increasingly low and erratic rainfalls, coupled with soil erosion by wind and the drying up of
Desertification
desertification is becoming a major problem as more and more of the world s land surface is turned into desert. The new deserts which are being created are
http://ypte.org.uk/docs/factsheets/env_facts/desertification.html

Extractions: Desertification Soils can be ruined easily in areas where seasonal rainfall is unreliable. Cutting down forests and trees, over-cultivation of the soil and over-grazing can all contribute to desertification. In poorer countries, farmers often know what needs to be done, but they and their families live so near to starvation that they cannot even afford to buy what they need to keep their families healthy, let alone attempt to solve their problems. In Europe and America too, some farmers have not acted wisely. They have sprayed their soils with chemicals to improve their crop yields. In many cases, the seeds they sow have been specially bred by a particular company to grow best when fed with the same companyÕs fertiliser. Soils have become dusty and are blown away by the wind, as they need natural fertilisers, rest from continual planting, and trees to shelter them from the wind. So just how big a problem is desertification? Estimates suggest that 35% of the earth's land surface is at risk, and the livelihoods of 850 million people are directly affected. 75% of the world's drier lands - 45,000,000 square kilometres are affected by desertification, and every year 6,000,000 hectares of agricultural land are lost and become virtual desert. The Sahara is thought to be advancing southwards by about 5-10 kilometres per year, which is a very considerable amount, when you remember that the Sahara is 5,150 kilometres across at its widest point.
Len Milich: Desertification
This same World Bank report defined desertification as a process of sustained decline of the biological productivity of arid and semiarid land;
http://ag.arizona.edu/~lmilich/desrtif.html

Extractions: Discussed at length during the 1992 United Nations Conference on Environment and Development, and driven by the renewed interest of the United Nations Environment Program (UNEP, 1992), desertification has reemerged on the international agenda as a topic of concern. Whether or not the deserts are growing, their population surely is; for example, drylands in the Middle East cover 99 percent of the surface area, and the region's rate of population growth is approximately 3 percent per year. Many millions of people have nowhere else to go since half the countries on earth lie partly or entirely in arid and semiarid zones, which cover one-third of the planet's land surface, 44 percent if the subhumid zone is included. In 1950, the population of these countries was 76 million; in 1985, it reached 205 million; and the forecast for 2000 is 300 million (Braverman, 1994). While overall population densities in most of the world's drylands are low overall, locally this may not be the case. For example, I estimate local population densities in the agricultural lands of the Niger-Nigeria border region to reach 148/sq. km. (Milich and Weiss, 1997). In some such densely-populated areas, demands on natural resources - arable land, grasslands for grazing, trees for fuelwood and browsing - are unsustainable given the indigenous systems in use at present. "The ballooning demand for resources that this growth represents almost inevitably generates extensive resource abuse in the short run," according to a
Desertification - A Threat To The Sahel
Describes how desertification may ruin a lush region of Africa.
http://www.eden-foundation.org/project/desertif.html

Extractions: The Lost Treasures of Eden Land covers 14.9 billion hectares of the earth's surface. A UNEP (United Nations Environmental Programme) study shows that 6.1 billion hectares are dryland of which 1 billion hectares are naturally hyperarid desert. The rest of the dryland has either become desert or is being threatened by desertification. One quarter of the world's population inhabit the drylands and depend on this area for their livelihood. The misconception that the Sahel is directly exposed to the Sahara has been widely accepted. The Sahara is sometimes pictured as a sea of sand dunes washing onto the Sahel exposing farmers to waves of sand that roll in from the desert, yearly swallowing large chunks of farming land. If true it would be understandable that projects plant green belts in order to defend the Sahel from the invasion. In reality the situation is much more complex. In some places such as parts of North Africa and Mauritania the Sahara directly threatens farming land. However in Niger the pastoral zone to the north of Tanout (the town 13km N. of Eden's field station) is well vegetated with many bushes and trees. It is in fact a natural green belt that protects farmers from the Sahara.
DESERTIFICATION OF ARID LANDS
Research paper about goes into detail about desertification.
http://www.ciesin.org/docs/002-193/002-193.html

Extractions: Reproduced, with permission, from: Dregne, H. E. 1986. Desertification of arid lands. In Physics of desertification, ed. F. El-Baz and M. H. A. Hassan. Dordrecht, The Netherlands: Martinus, Nijhoff. ABSTRACT INTRODUCTION Desertification of the arid lands of the world has been proceedingsometimes rapidly, sometimes slowlyfor more than a thousand years. It has caused untold misery among those most directly affected, yet environmental destruction continues. Until recently, few if any lessons seemed to have been learned from the past, in part because the problem was an insidious one that went unrecognized in its early stages or was seen as a local one affecting only a small population, and in part because new land was always available to start over again. As long as remedial action could be deferred by moving on to new frontiers, land conservation had little appeal. It was not until the 20th centurywhen easy land expansion came to an endthat governments and people finally realized that continued careless degradation of natural resources threatened their future. INTERNATIONAL DIRECTIONS The decade of the 1950's witnessed the first worldwide effort to call attention to the problems and potentials of arid regions. It started when the United Nations Educational, Scientific, and Cultural Organization (UNESCO) launched its Major Project on Scientific Research on Arid Lands in 1951. That project led to publication of a newsletter, the provision for funds for establishing and strengthening arid land research institutes, organization of conferences and symposia, and publication of a series of research reviews and special reports on a wide range of topics. The Major Project was terminated in 1962 and the arid land program was merged with the broader UNESCO natural resource program.
US Dept Of State - Publications
Explores the problems of desertification, the warning signs, and how we can reduce it using proper land management.
http://usinfo.state.gov/products/pubs/desertific/

Extractions: President Franklin D. Roosevelt Internally displaced people walk through a dust storm, Denan, Ethiopia. (AP Photo/Brennan Linsley) The word "desertification" may not be familiar to some readers; however, it goes to the core of global environmental concerns that increasingly preoccupy people on all continents of the globe. This book, published by the State Department's Bureau of Oceans and International Environmental and Scientific Affairs and the Bureau of International Information Programs, attempts to define, explain, and offer suggestions about how to deal with the insidious process of land degradation in agricultural and forest areas worldwide that is known as desertification. Although some aspects are hidden from human sight, desertification affects everybody on the planet by robbing global soil of nutrients, degrading agricultural production, spreading dust throughout the globe, contaminating water, and making it far more difficult to remedy poverty and hunger.
IMPACTS - Desertification
Detailed report supported by Greenpeace that examines the potential implications of global climate change for the Mediterranean region.
http://archive.greenpeace.org/climate/science/reports/desertification.html

Extractions: climate science Climate Change and the Mediterranean Region Executive Summary Water shortages and poor harvests during the droughts of the early 1990s exposed the acute vulnerability of the Mediterranean region to climatic extremes. Against this backdrop, the prospect of a major climate change brought about by human activities is a source of growing concern, raising serious questions over the sustainability of the region. This report examines the potential implications of global climate change for the Mediterranean region. Drawing on the results of recent studies, it reviews possible changes in climate together with recent trends, the potential impacts of climate change and the implications for sustainable development. One key finding is that future climate change could critically undermine efforts for sustainable development in the Mediterranean region. In particular, climate change may add to existing problems of desertification, water scarcity and food production, while also introducing new threats to human health, ecosystems and national economies of countries. The most serious impacts are likely to be felt in North African and eastern Mediterranean countries. The report concludes that while there is some scope for adaptation, ensuring the long-term sustainability of the region requires urgent action to cut global emissions of greenhouse gases.
Desertification
desertification is the expansion of dry lands due to poor agricultural practices (e.g. overgrazing, degradation of soil fertility and structure),
http://www.uwsp.edu/geo/faculty/ritter/geog101/textbook/biogeography/desertifica

Extractions: Contents Glossary Atlas ... Biogeography of the Earth Desertification is the expansion of dry lands due to poor agricultural practices (e.g. overgrazing, degradation of soil fertility and structure), improper soil moisture management, salinization and erosion, forest removal, and climate change. BE.43 Desertification in Africa Courtesy FAO Two common misconceptions prevail about desertification, that it spreads from a desert core and drought is responsible. Desertification spreads outward from any where excessive abuse of the land occurs and far from any climatic desert. Droughts do increase the possibility of desertification if the carrying capacity of non-irrigated land is exceeded. Well-managed land can recover from the effects of drought. Combining drought with land abuse sets the stage for desertification. Desertification comes about by a complex interaction between the natural environment and human activities. The cause may vary from region to region on account of economic conditions, population pressure, agricultural practices, and politics. Human activities that destroys surface vegetation, degrades soil structure and fertility, impedes water infiltration, and causes soil drying promotes desertification. This is especially true for the fragile transition zone between arid and semiarid land where human activity has stretched the ecosystem to its limit causing expansion of deserts.
Earth Observatory Feature: Defining Desertification
Many people extrapolated from these local examples of desertification to propose that the whole Sahel was becoming a desert, but no one had surveyed the
http://earthobservatory.nasa.gov/Study/Desertification/

Extractions: Townshend had just returned from NASA Goddard Space Flight Center in Greenbelt, Maryland, where remote-sensing ecologist Compton Tucker had developed a new scale, or index, Andrew Heavens. The Sahel stretches across Africa, roughly 15 degrees north of the Equator. Satellite measurements of vegetation reveal it as a transition zone between the sands of the Sahara and the jungles of the Congo in the heart of Africa. This map shows vegetation in the final two weeks of June 2005, near the end of the dry season in the Sahel. Dark green indicates dense vegetation, while light green and beige indicate sparse vegetation and barren land. (Map by Robert Simmon, based on GIMMS vegetation data and World Wildlife Fund ecoregions data.) Temporary Drought or Permanent Desert? Ferdinand Reus and David Haberlah. Subscribe to the Earth Observatory
Desert - In Iceland
desertification IN ICELAND. Klick The extremely active soil erosion in The project to assess erosion and desertification in Iceland was awarded the
http://www.rala.is/desert/
Photos: Desertification - The Lab - Australian Broadcasting Corporation's Gatewa
2006 is the International Year of Deserts and desertification, celebrating the beauty of deserts while calling attention to desertification, which threatens
http://www.abc.net.au/science/photos/desertification/

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

1-20 of 84 1 | 2 | 3 | 4 | 5 | Next 20