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In arid climates such as the southwestern United States, livestock grazing has severely degraded [[riparian areas]], the wetland environment adjacent to rivers or streams. The [[Environmental Protection Agency]] states that agriculture has a greater impact on stream and river contamination than any other [[nonpoint source]]. Improper grazing of riparian areas can contribute to [[nonpoint source pollution]] of riparian areas.<ref>{{cite web |url=http://ohioline.osu.edu/ls-fact/0002.html |title=Negative Effects of Livestock Grazing Riparian Areas |last1=Hoorman |first1=James |last2=McCutcheon |first2=Jeff |website=ohioline.osu.edu |publisher=Ohio State University School of Environment and Natural Resources |access-date=15 June 2015 |archive-url=https://web.archive.org/web/20150617072453/http://ohioline.osu.edu/ls-fact/0002.html |archive-date=June 17, 2015 }}</ref> Riparian zones in arid and semiarid environments have been called [[biodiversity hotspot]]s.<ref>{{cite journal | author=Luoma, Jon | title=Discouraging Words | journal=[[Audubon (magazine)|Audubon]] | volume=88 | date=September 1986 | issue=92}}</ref> The water, higher [[Biomass (ecology)|biomass]], favorable [[microclimate]] and periodic flood events together produce higher biological diversity than in the surrounding uplands.<ref>{{cite web|url=http://www.publiclandsranching.org/htmlres/wr_lifeblood_west.htm |title=Lifeblood of the West |access-date=August 8, 2007 |last=Kauffman |first=J. Boone}}</ref> In 1990, "according to the [[Arizona]] state park department, over 90% of the original riparian zones of Arizona and [[New Mexico]] are gone". A 1988 report of the [[Government Accountability Office]] estimated that 90% of the 5,300 miles of riparian habitat managed by the [[Bureau of Land Management]] in [[Colorado]] was in unsatisfactory condition, as was 80% of [[Idaho]]'s riparian zones, concluding that "poorly managed livestock grazing is the major cause of degraded riparian habitat on federal rangelands".<ref>{{cite journal | author=Wuerthner, George | title=The Price is Wrong | journal=[[Sierra (magazine)|Sierra]] | date= September–October 1990}}</ref>
A 2013 FAO report estimated livestock were responsible for 14.5% of [[Anthropogenic greenhouse gases|anthropogenic greenhouse gas emissions]].<ref>{{cite web|url=http://www.fao.org/ag/againfo/resources/en/publications/tackling_climate_change/index.htm|title=Tackling climate change through livestock // FAO's Animal Production and Health Division|website=Fao.org|access-date=16 August 2018}}</ref><ref>{{cite report |authorsauthor=Gerber, P.J., |author2=Steinfeld, H., |author3=Henderson, B., |author4=Mottet, A., |author5=Opio, C., |author6=Dijkman, J., |author7=Falcucci, A. & |author8=Tempio, G. |date=2013 |title=Tackling climate change through livestock – A global assessment of emissions and mitigation opportunities |url=http://www.fao.org/3/a-i3437e.pdf |publisher=Food and Agriculture Organization of the United Nations (FAO) |pages=1–139 |isbn=978-92-5-107921-8 |access-date=3 October 2019}}</ref> Grazing is common in [[New Zealand]]; in 2004, [[methane]] and [[nitrous oxide]] from agriculture made up somewhat less than half of New Zealand's greenhouse gas emissions, of which most is attributable to [[livestock]].<ref>{{cite web|url=http://www.maf.govt.nz/climatechange/slm/vggr/page-01.htm#P610_60455|title=New Zealand Ministry of Agriculture and Forestry – Voluntary Greenhouse Gas Reporting Feasibility Study – Summary|website=Maf.govt.nz|access-date=16 August 2018|archive-url=https://web.archive.org/web/20100526205034/http://www.maf.govt.nz/climatechange/slm/vggr/page-01.htm |archive-date=2010-05-26}}</ref> A 2008 [[United States Environmental Protection Agency]] report on emissions found agriculture was responsible for 6% of total United States greenhouse gas emissions in 2006. This included [[rice]] production, [[enteric fermentation]] in domestic livestock, livestock [[manure]] management, and agricultural [[soil management]], but omitted some things which might be attributable to agriculture.<ref name="epa.gov">[http://www.epa.gov/climatechange/emissions/usinventoryreport.html U.S. Greenhouse Gas Inventory Reports] {{webarchive|url=https://web.archive.org/web/20111218171807/http://www.epa.gov/climatechange/emissions/usinventoryreport.html |date=2011-12-18 }}</ref> Studies comparing the [[methane emissions]] from grazing and feedlot cattle concluded that grass-fed cattle produce much more methane than grain-fed cattle.<ref name=Harper1999>{{cite journal|author1=Harper LA|author2=Denmead OT|author3=Freney JR|author4=Byers FM|title=Direct measurements of methane emissions from grazing and feedlot cattle |journal=J Anim Sci |date=Jun 1999 |volume=77 |issue=6 |pages=1392–401 |pmid=10375217 |url=http://www.journalofanimalscience.org/content/77/6/1392.full.pdf+html |access-date=29 March 2014 |doi=10.2527/1999.7761392x}}</ref><ref name=Capper2012>{{cite journal|last=Capper|first=JL|title=Is the Grass Always Greener? Comparing the Environmental Impact of Conventional, Natural and Grass-Fed Beef Production Systems|journal=Animals|date=Apr 10, 2012|volume=2|issue=2|pages=127–43|doi=10.3390/ani2020127|pmid=26486913|pmc=4494320|doi-access=free }}</ref><ref name=Pelletier2010>{{cite journal|author1=Pelletier N|author2= Pirogb R|author3= Rasmussen R|title=Comparative life cycle environmental impacts of three beef production strategies in the Upper Midwestern United States|journal=Agricultural Systems|date=Jul 2010|volume=103|issue=6|pages=380–389|doi=10.1016/j.agsy.2010.03.009}}</ref> One study in the ''[[Journal of Animal Science]]'' found four times as much, and stated: "these measurements clearly document higher CH<sub>4</sub> production for cattle receiving low-quality, high-fiber diets than for cattle fed high-grain diets".<ref name=Harper1999/>
==See also==
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