Editing Soil erosion (section)

==Global environmental effects==
[[File:Runoff and filtersoxx.ogv|left|thumb|468x468px]]
[[File:Water erosion map.jpg|thumb|325px|World map indicating areas that are vulnerable to high rates of water erosion]]
[[File:Rano Raraku quarry.jpg|thumb|During the 17th and 18th centuries, [[Easter Island]] experienced severe erosion due to [[deforestation]] and unsustainable agricultural practices. The resulting loss of topsoil ultimately led to ecological collapse, causing mass [[starvation]] and the complete disintegration of the Easter Island civilization.<ref>{{cite journal|author=Dangerfield, Whitney|title=The Mystery of Easter Island|journal=Smithsonian Magazine|date=April 1, 2007|url=http://www.smithsonianmag.com/people-places/The_Mystery_of_Easter_Island.html}}</ref><ref>{{cite book|author=Montgomery, David|chapter=Islands in time|title=Dirt: The Erosion of Civilizations|publisher=University of California Press|date=October 2, 2008|edition=1st|isbn=978-0-520-25806-8|chapter-url=https://books.google.com/books?id=HSu8r15-nnoC&pg=PA217}}</ref>]]

Due to the severity of its ecological effects, and the scale on which it is occurring, erosion constitutes one of the most significant global environmental problems we face today.<ref name="toy-2002-p1">{{cite book|author=Toy, Terrence J.|title=Soil Erosion: Processes, Prediction, Measurement, and Control|publisher=John Wiley & Sons|year=2002|isbn=978-0-471-38369-7|page=1|url=https://books.google.com/books?id=7YBaKZ-28j0C&pg=PA1|display-authors=etal}}</ref>

===Land degradation===
Water and wind erosion are now the two primary causes of [[land degradation]]; combined, they are responsible for 84% of degraded acreage.<ref name="Springer"/>

Each year, about 75 billion tons of soil is eroded from the land—a rate that is about 13–40 times as fast as the natural rate of erosion.<ref>{{cite book|author=Zuazo, Victor H.D.|author2=Pleguezuelo, Carmen R.R.|name-list-style=amp|chapter=Soil-erosion and runoff prevention by plant covers: a review|editor=Lichtfouse, Eric|display-editors=etal|title=Sustainable agriculture|publisher=Springer|year=2009|isbn=978-90-481-2665-1|page=785|chapter-url=https://books.google.com/books?id=7cP-2jIIO2wC&pg=PA785}}</ref> Approximately 40% of the world's agricultural land is seriously degraded.<ref>{{cite news|author=Sample, Ian|title=Global food crisis looms as climate change and population growth strip fertile land|work=The Guardian|date=August 30, 2007|url=https://www.theguardian.com/environment/2007/aug/31/climatechange.food}}</ref> According to the [[United Nations]], an area of fertile soil the size of Ukraine is lost every year because of [[drought]], [[deforestation]] and [[climate change]].<ref>{{cite news|author=Smith, Kate|author2=Edwards, Rob|name-list-style=amp|title=2008: The year of global food crisis|work=The Herald (Scotland)|date=March 8, 2008|url=http://www.heraldscotland.com/2008-the-year-of-global-food-crisis-1.828546}}</ref> In [[Africa]], if current trends of soil degradation continue, the continent might be able to feed just 25% of its population by 2025, according to [[United Nations University|UNU]]'s Ghana-based Institute for Natural Resources in Africa.<ref>{{cite web|url=http://news.mongabay.com/2006/1214-unu.html|website=news.mongabay.com|title=Africa may be able to feed only 25% of its population by 2025|archive-url=https://web.archive.org/web/20061216080905/http://news.mongabay.com/2006/1214-unu.html|archive-date=2006-12-16 |date=2006-12-14 }}</ref>

Recent [[Simulation|modeling]] developments have quantified rainfall erosivity at global scale using high temporal resolution (<30 min) and high fidelity rainfall recordings. The results is an extensive global data collection effort produced the Global Rainfall Erosivity Database (GloREDa) which includes rainfall erosivity for 3,625 stations and covers 63 countries. This first ever Global Rainfall Erosivity Database was used to develop a global erosivity map <ref>{{Cite journal|last1=Panagos|first1=Panos|last2=Borrelli|first2=Pasquale|last3=Meusburger|first3=Katrin|last4=Yu|first4=Bofu|last5=Klik|first5=Andreas|last6=Lim|first6=Kyoung Jae|last7=Yang|first7=Jae E.|last8=Ni|first8=Jinren|last9=Miao|first9=Chiyuan|date=2017-06-23|title=Global rainfall erosivity assessment based on high-temporal resolution rainfall records|journal=Scientific Reports|language=En|volume=7|issue=1|pages=4175|doi=10.1038/s41598-017-04282-8|pmid=28646132|pmc=5482877|issn=2045-2322|bibcode=2017NatSR...7.4175P}}</ref> at 30 arc-seconds(~1 km) based on sophisticated geostatistical process. According to a new study<ref>{{Cite journal|last1=Borrelli|first1=Pasquale|last2=Robinson|first2=David A.|last3=Fleischer|first3=Larissa R.|last4=Lugato|first4=Emanuele|last5=Ballabio|first5=Cristiano|last6=Alewell|first6=Christine|last7=Meusburger|first7=Katrin|last8=Modugno|first8=Sirio|last9=Schütt|first9=Brigitta|date=2017-12-08|title=An assessment of the global impact of 21st century land use change on soil erosion|journal=Nature Communications|language=En|volume=8|issue=1|pages=2013|doi=10.1038/s41467-017-02142-7|pmid=29222506|pmc=5722879|issn=2041-1723|bibcode=2017NatCo...8.2013B}}</ref> published in Nature Communications, almost 36 billion tons of soil is lost every year due to water, and deforestation and other changes in land use make the problem worse. The study investigates global soil erosion dynamics by means of high-resolution spatially distributed modelling (c. 250 × 250 m cell size). The geo-statistical approach allows, for the first time, the thorough incorporation into a global soil erosion model of land use and changes in land use, the extent, types, spatial distribution of global croplands and the effects of different regional cropping systems.

The loss of [[soil fertility]] due to erosion is further problematic because the response is often to apply chemical fertilizers, which leads to further water and [[soil pollution]], rather than to allow the land to regenerate.<ref>{{cite book|author=Potter, Kenneth W.|chapter=Impacts of agriculture on aquatic ecosystems in the humid United States|editor=DeFries, Ruth S.|display-editors=etal|title=Ecosystems And Land Use Change|publisher=American Geophysical Union|year=2004|isbn=978-0-87590-418-4|page=34|chapter-url=https://books.google.com/books?id=CVN5X57pjnAC&pg=PA34|display-authors=etal}}{{Dead link|date=May 2023 |bot=InternetArchiveBot |fix-attempted=yes }}</ref>

===Sedimentation of aquatic ecosystems===
Soil erosion (especially from agricultural activity) is considered to be the leading global cause of diffuse [[water pollution]], due to the effects of the excess sediments flowing into the world's waterways. The sediments themselves act as pollutants, as well as being carriers for other pollutants, such as attached pesticide molecules or heavy metals.<ref>{{Cite book|author=Da Cunha, L.V.|chapter=Sustainable development of water resources|editor=Bau, João|title=Integrated Approaches to Water Pollution Problems: Proceedings of the International Symposium (SISIPPA) (Lisbon, Portugal 19–23 June 1989)|publisher=Taylor & Francis|year=1991|isbn=978-1-85166-659-1|pages=12–13|chapter-url=https://books.google.com/books?id=79ztZNhaNvMC&pg=PA12}}</ref>

The effect of increased sediments loads on aquatic ecosystems can be catastrophic. Silt can smother the spawning beds of fish, by filling in the space between gravel on the stream bed. It also reduces their food supply, and causes major respiratory issues for them as sediment enters their [[gills]]. The [[biodiversity]] of aquatic plant and algal life is reduced, and invertebrates are also unable to survive and reproduce. While the sedimentation event itself might be relatively short-lived, the ecological disruption caused by the mass die off often persists long into the future.<ref>{{Cite book|author=Merrington, Graham|chapter=Soil erosion|title=Agricultural Pollution: Environmental Problems and Practical Solutions|publisher=Taylor & Francis|year=2002|isbn=978-0-419-21390-1|pages=77–78|chapter-url=https://books.google.com/books?id=ITFYBiQ_-VAC&pg=PA77}}</ref>

One of the most serious and long-running water erosion problems worldwide is in the [[People's Republic of China]], on the middle reaches of the [[Yellow River]] and the upper reaches of the [[Yangtze River]]. From the [[Yellow River]], over 1.6&nbsp;billion tons of sediment flows into the ocean each year. The [[sediment]] originates primarily from water erosion in the [[Loess Plateau]] region of the northwest.<ref>{{Cite journal|title=Estimating soil erosion risk and evaluating erosion control measures for soil conservation planning at Koga Watershed, Ethiopian Highlands|last1=Molla|first1=Tegegne|last2=Sisheber|first2=Biniam|date=2016-09-08|doi=10.5194/se-2016-120|doi-access=free}}</ref>

===Airborne dust pollution===
Soil particles picked up during wind erosion of soil are a major source of [[air pollution]], in the form of [[airborne particulates]]—"dust". These airborne soil particles are often contaminated with toxic chemicals such as pesticides or petroleum fuels, posing ecological and public health hazards when they later land, or are inhaled/ingested.<ref>{{cite book|author=Majewski, Michael S.|author2=Capel, Paul D.|name-list-style=amp|title=Pesticides in the Atmosphere: Distribution, Trends, and Governing Factors|publisher=CRC Press|year=1996|isbn=978-1-57504-004-2|page=121|url=https://books.google.com/books?id=T9pRfLqXajQC&pg=PA121}}</ref><ref name="Science Daily 1999-07-14">{{cite web|author=Science Daily|date=1999-07-14|url=https://www.sciencedaily.com/releases/1999/07/990714073433.htm|title=African Dust Called A Major Factor Affecting Southeast U.S. Air Quality|access-date=2007-06-10}}</ref><ref>{{cite book|author=Nowell, Lisa H.|title=Pesticides in Stream Sediment and Aquatic Biota: Distribution, Trends, and Governing Factors|publisher=CRC Press|year=1999|isbn=978-1-56670-469-4|page=199|url=https://books.google.com/books?id=UzpDTEO3ZVcC&pg=PA199|display-authors=etal}}</ref><ref>{{cite book|author=Shao, Yaping|chapter=Wind-erosion and wind-erosion research|title=Physics and Modelling of Wind Erosion|publisher=Springer|year=2008|isbn=978-1-4020-8894-0|page=3|chapter-url=https://books.google.com/books?id=XSwwVeraxjcC&pg=PA3}}</ref>

Dust from erosion acts to suppress rainfall and changes the [[sky]] color from blue to white, which leads to an increase in red sunsets{{Citation needed|date=October 2017}}. Dust events have been linked to a decline in the health of [[coral reef]]s across the Caribbean and Florida, primarily since the 1970s.<ref>{{cite web|author=U. S. Geological Survey|author-link=U. S. Geological Survey|year=2006|url=http://coastal.er.usgs.gov/african_dust/|title=Coral Mortality and African Dust|access-date=2007-06-10}}</ref> Similar dust plumes originate in the [[Gobi desert]], which combined with pollutants, spread large distances downwind, or eastward, into North America.<ref name="Gobi">{{cite web|author=James K. B. Bishop|author2=Russ E. Davis|author3=Jeffrey T. Sherman|name-list-style=amp|year=2002|url=http://www-ocean.lbl.gov/people/bishop/bishoppubs/paparobots.html|title=Robotic Observations of Dust Storm Enhancement of Carbon Biomass in the North Pacific|work=Science 298|pages=817–821|access-date=2009-06-20|archive-url=https://web.archive.org/web/20111009142528/http://www-ocean.lbl.gov/people/bishop/bishoppubs/paparobots.html|archive-date=2011-10-09|url-status=live}}</ref>