Editing Geography of Mexico (section)

==Environmental conditions==
[[File:Rio_Grande_in_Big_Bend_NP.jpg|thumb|right|250px|The Rio Grande at Big Bend National Park,
on the Mexico–U.S. border]]

Mexico faces significant environmental challenges damaging nearly all sections of the country. Vast expanses of southern and southeastern tropical forests have been denuded due to mineral resource extraction,<ref>{{cite journal |last1=Bebbington |first1=Anthony J. |last2=Bebbington |first2=Denise Humphreys |last3=Sauls |first3=Laura Aileen |last4=Rogan |first4=John |last5=Agrawal |first5=Sumali |last6=Gamboa |first6=César |last7=Imhof |first7=Aviva |last8=Johnson |first8=Kimberly |last9=Rosa |first9=Herman |last10=Royo |first10=Antoinette |last11=Toumbourou |first11=Tessa |last12=Verdum |first12=Ricardo |title=Resource extraction and infrastructure threaten forest cover and community rights |journal=Proceedings of the National Academy of Sciences |date=26 December 2018 |volume=115 |issue=52 |pages=13164–13173 |doi=10.1073/pnas.1812505115 |pmid=30509982 |pmc=6310830 |bibcode=2018PNAS..11513164B |doi-access=free }}</ref><ref>{{cite news |last1=Hill |first1=David |title=Canadian mining doing serious environmental harm, the IACHR is told |url=https://www.theguardian.com/environment/andes-to-the-amazon/2014/may/14/canadian-mining-serious-environmental-harm-iachr |access-date=20 August 2019 |work=The Guardian |date=17 May 2014}}</ref> and then, far behind in second place, for cattle-raising and agriculture. For example, tropical forests covered almost half of the state of Tabasco in 1940 but less than 10% by the late 1980s. During the same period, pastureland increased from 20 to 60% of the state's total area.<ref name=":0">{{Cite web|title=Mexico - Environmental Conditions|url=http://countrystudies.us/mexico/51.htm|access-date=2021-03-08|website=countrystudies.us}}</ref> Analysts reported similar conditions in other tropical sections of Mexico. [[Deforestation]] and [[desertification]] has contributed to serious levels of soil erosion nationwide. In 1985 the government classified almost 17% of all land as totally eroded, 31% in an accelerated state of erosion, and 38% demonstrating signs of incipient erosion.<ref name=":0" />  Mexico has developed a [[Biodiversity Action Plan]] to address issues of [[endangered species]] and [[Habitat (ecology)|habitat]]s that merit protection.<ref>{{Cite journal|last1=Faizi|first1=S.|last2=Ravichandran|first2=M.|title=CBD: Sovereignty is Not Negotiable|date=December 2009|url=http://dx.doi.org/10.1080/14888386.2009.9712861|journal=Biodiversity|volume=10|issue=4|pages=45–46|doi=10.1080/14888386.2009.9712861|bibcode=2009Biodi..10d..45F |s2cid=154242750|issn=1488-8386}}</ref>

[[File:SierraGordaQueretaro.JPG|thumb|left|[[Sierra Gorda]]]]

Soil destruction is particularly pronounced in the north and northwest, with more than 60% of land considered in a total or accelerated state of erosion. Fragile because of its semiarid and arid character, the soil of the region has become increasingly damaged through excessive cattle-raising and irrigation with waters containing high levels of salinity. The result is a mounting problem of desertification throughout the region.<ref name=":0" />

Mexico's vast coastline faces a different, but no less difficult, series of environmental problems. For example, inadequately regulated petroleum exploitation in the [[Coatzacoalcos]]-[[Minatitlán, Veracruz|Minatitlán]] zone in the Gulf of Mexico has caused serious damage to the waters and fisheries of [[Río Coatzacoalcos]]. The deadly [[1992 Guadalajara explosions|explosion that racked a working-class neighborhood]] in Guadalajara in April 1992 serves as an appropriate symbol of environmental damage in Mexico. More than {{convert|1000|oilbbl}} of gasoline seeped from a corroded Mexican Petroleum (Petróleos Mexicanos—Pemex) pipeline into the municipal sewer system, where it combined with gases and industrial residuals to produce a massive explosion that killed 190 persons and injured nearly 1,500 others.{{citation needed|date=February 2022}} [[Tourism in Mexico|Mexico's tourism industry]] impacts the environment but this can be reduced.<ref name="Rosario-et-al-2017">{{cite journal | last1=María del Rosario | first1=Reyes-Santiago | last2=Patricia S. | first2=Sánchez-Medina | last3=René | first3=Díaz-Pichardo | title=Eco-innovation and organizational culture in the hotel industry | journal=[[International Journal of Hospitality Management]] | publisher=[[Elsevier]] | volume=65 | year=2017 | issn=0278-4319 | doi=10.1016/j.ijhm.2017.06.001 | pages=71–80 | s2cid=157461751}}</ref> Carmona-Morena et al. 2004 & Sánchez-Medina et al. 2015 find the country's environmental enforcement in the tourism sector varies between little and nonexistent.<ref name="Rosario-et-al-2017" /> Sánchez-Medina finds some change toward environmentally benign practices still occurs but is voluntary and has motives other than financial reward or fear of enforcement.<ref name="Rosario-et-al-2017" /> They also find that such progress is slowed by the lack of financial wherewithal these tourism enterprises have.<ref name="Rosario-et-al-2017" />

[[File:03_Tour_Cañon_(122).JPG|thumb|right|[[Cañón del Sumidero]]]]

[[Air pollution in Mexico City|Mexico City confronts authorities]] with perhaps their most daunting environmental challenge. Geography and extreme population levels have combined to produce one of the world's most polluted urban areas. Mexico City sits in a valley surrounded on three sides by mountains, which [[Valley of Mexico#Air pollution|serve to trap contaminants]] produced by the metropolitan area's 15 million residents. One government study in the late 1980s determined that nearly 5 million tons of contaminants were emitted annually in the [[atmosphere]], a tenfold increase over the previous decade. Carbons and hydrocarbons from the region's more than 3 million vehicles account for approximately 80% of these contaminants, with another 15%, primarily of [[sulfur]] and [[nitrogen]], coming from industrial plants. The resulting dangerous mix is responsible for a wide range of respiratory illnesses. One study of twelve urban areas worldwide in the mid-1980s concluded that the residents of Mexico City had the highest levels of [[lead]] and [[cadmium]] in their blood. The volume of [[pollutants]] from Mexico City has damaged the surrounding [[ecosystem]] as well. For example, wastewater from Mexico City that flows north and is used for irrigation in the state of [[Hidalgo (state)|Hidalgo]] has been linked to congenital birth defects and high levels of gastrointestinal diseases in that state.

[[File:Pantanos_de_Centla_2.JPG|thumb|left|250px|[[Usumacinta River]], in "Tres Brazos" the Usumacinta joins to San Pedrito river and [[Grijalva river]], in the Wetlands of [[Centla]], biosphere reserve, in [[Tabasco]].]]

Beginning in the mid-1980s, the government enacted numerous antipollution policies in Mexico City with varied degrees of success. Measures such as vehicle emissions inspections, the introduction of unleaded gasoline, and the installation of catalytic converters on new vehicles helped reduce pollution generated by trucks and buses. In contrast, one of the government's most prominent actions, the No Driving Day program, may have inadvertently contributed to higher pollution levels. Under the program, metropolitan area residents were prohibited from driving their vehicles one day each work week based on the last number of their license plate. However, those with the resources to do so purchased additional automobiles to use on the day their principal vehicle was prohibited from driving, thus adding to the region's vehicle stock. Thermal inversions reached such dangerous levels at various times in the mid-1990s that the government declared pollution emergencies, necessitating sharp temporary cutbacks in vehicle use and industrial production.

Mexico had a 2018 [[Forest Landscape Integrity Index]] mean score of 6.82/10, ranking it 63rd globally out of 172 countries.<ref name="FLII-Supplementary">{{cite journal|last1=Grantham|first1=H. S.|last2=Duncan|first2=A.|last3=Evans|first3=T. D.|last4=Jones|first4=K. R.|last5=Beyer|first5=H. L.|last6=Schuster|first6=R.|last7=Walston|first7=J.|last8=Ray|first8=J. C.|last9=Robinson|first9=J. G.|last10=Callow|first10=M.|last11=Clements|first11=T.|last12=Costa|first12=H. M.|last13=DeGemmis|first13=A.|last14=Elsen|first14=P. R.|last15=Ervin|first15=J.|last16=Franco|first16=P.|last17=Goldman|first17=E.|last18=Goetz|first18=S.|last19=Hansen|first19=A.|last20=Hofsvang|first20=E.|last21=Jantz|first21=P.|last22=Jupiter|first22=S.|last23=Kang|first23=A.|last24=Langhammer|first24=P.|last25=Laurance|first25=W. F.|last26=Lieberman|first26=S.|last27=Linkie|first27=M.|last28=Malhi|first28=Y.|last29=Maxwell|first29=S.|last30=Mendez|first30=M.|last31=Mittermeier|first31=R.|last32=Murray|first32=N. J.|last33=Possingham|first33=H.|last34=Radachowsky|first34=J.|last35=Saatchi|first35=S.|last36=Samper|first36=C.|last37=Silverman|first37=J.|last38=Shapiro|first38=A.|last39=Strassburg|first39=B.|last40=Stevens|first40=T.|last41=Stokes|first41=E.|last42=Taylor|first42=R.|last43=Tear|first43=T.|last44=Tizard|first44=R.|last45=Venter|first45=O.|last46=Visconti|first46=P.|last47=Wang|first47=S.|last48=Watson|first48=J. E. M.|title=Anthropogenic modification of forests means only 40% of remaining forests have high ecosystem integrity - Supplementary Material|journal=Nature Communications|volume=11|issue=1|year=2020|page=5978|issn=2041-1723|doi=10.1038/s41467-020-19493-3|pmid=33293507|pmc=7723057|doi-access=free|bibcode=2020NatCo..11.5978G }}</ref>