Climate Change and U.S.-Mexico Border Communities

Abstract

While the U.S.-Mexico border has been called a “third country” and has been identified as a distinct region (Anzaldua 1987), the challenges it faces are due in large measure to its high degree of integration into global processes of economic and environmental change. The border region is characterized by a so-called “double exposure” (Leichenko and O’Brien 2008)—meaning that environmental change in the region is driven by accelerated processes of global economic integration (such as foreign-owned industries and international migration) coupled with intensive climate change. It is critical to understand the drivers of climate-related vulnerability and capacities for adaptation in the region in the context of the region’s distinct history and contemporary challenges, shared climate regime, transboundary watersheds and airsheds, and interdependent economies and cultures.

Chapter citation: Wilder, M., G. Garfin, P. Ganster, H. Eakin, P. Romero-Lankao, F. Lara-Valencia, A. A. Cortez-Lara, S. Mumme, C. Neri, and F. Muñoz-Arriola. 2013. “Climate Change and U.S.-Mexico Border Communities.” In Assessment of Climate Change in the Southwest United States: A Report Prepared for the National Climate Assessment, edited by G. Garfin, A. Jardine, R. Merideth, M. Black, and S. LeRoy, 340–384. A report by the Southwest Climate Alliance. Washington, DC: Island Press.

Endnotes

• i The Paso del Norte area includes the Ciudad Juárez municipality in Chihuahua, El Paso County in Texas, and Doña Ana County in New Mexico.

• ii Among the paired cities in the western portion of the border region are: San Diego, California-Tijuana, Baja California Norte; Calexico, California-Mexicali, Baja California Norte; Yuma, Arizona-San Luis Río Colorado, Sonora; Nogales, Arizona-Nogales, Sonora; Naco, Arizona-Naco, Sonora; Douglas, Arizona-Agua Prieta, Sonora; Columbus, Texas-Las Palomas, Chihuahua; El Paso, Texas-Ciudad Juárez, Chihuahua.

• iii For further discussion of interannual and multidecadal precipitation variability on the U.S. side of the border, see Chapter 4; for Mexico, see Diaz-Castro et al. 2002; Higgins and Shi 2001; Higgins, Chen, and Douglas 1999; Méndez and Magaña 2010; and Seager et al. 2009.

• iv For further discussion of ENSO (El Niño-Southern Oscillation), droughts, floods and hydrological planning on the U.S. side of the border, see Chapters 4 and 5 and Garfin, Crimmins, and Jacobs 2007; for Mexico, see Magaña and Conde 2000; Brito-Castillo et al. 2002; Brito-Castillo et al. 2003; Pavia, Graef, and Reyes 2006; Gochis, Brito-Castillo, and Shuttleworth 2007; Ray et al. 2007; Seager et al. 2009; Stahle et al. 2009; and Méndez and Magaña 2010.

• v These studies include Hurd and Coonrod 2007; Dominguez, Cañon, and Valdes 2010; Montero Martinez et al. 2010; Gutzler and Robbins 2011; Kunkel 2011; Reclamation 2011; Magaña, Zermeño, and Neri 2012; Scott et al. 2012; and Chapter 6 of this report.

• vi For a discussion of downscaling methods, see Chapter 6, Section 6 of this document.

• vii One notable aspect of mean temperature projections for the border region and for western North America more generally is that temperatures are projected to increase over the course of the century, regardless of the emissions scenario.

• viii Consistent with these estimates are statistically downscaled projections of increased maximum and minimum temperatures in summer and winter, with the highest minimum temperature increases in the western Sonoran Desert and the highest maximum temperature increases in the northern Chihuahuan Desert. One set of statistically downscaled estimates of temperature changes for the north of the border region (high-and low-emission scenario models) are summarized in Table 16.2 and another set of statistically downscaled estimates for Mexican border states in the region (SRES A2) in are summarized in Table 16.3.

• ix Garcia-Cueto, Tejeda-Martinez, and Jáuregui-Ostos (2010) note that, in the historic record for the border city of Mexicali, Baja California Norte, the duration and intensity of heat waves have increased for all summer months, there are 2.3 times more heat waves now than in the decade of the 1970s, and that the high-emissions SRES A2 projections show that for the 2020s, 2050s, and 2080s, heat waves could increase (relative to 1961–1990), by 2.1, 3.6, and 5.1 times, respectively.

• x A special consideration for the western part of the border region in the wintertime could be that the circulation may change so that there will be fewer cyclones and more anticyclones (Favre and Gershunov 2009) resulting in (a) less frequent precipitation (this is well corroborated by several studies and in many models) and also in (b) more frequent cold spells. The second result is less certain, studied only in one model—CNRM-CM3 by Favre and Gershunov (2009), in which Mexican data were explicitly considered. Some recent results from Pierce et al. (2012), based on several models, suggest that the magnitude of cold outbreaks in January (see Pierce et al. 2012, Figure 6) will not likely diminish in California. This signal should probably extend south of the border some into Baja California (see Chapter 7).

• xi Although across the border region winter precipitation is perhaps less substantial than summer precipitation, it is during this season that major dams store water that is used in the onset of the agricultural activities in the spring and summer months. Baja California, with its winterdominated Mediterranean annual cycle of precipitation, is projected to have the highest percent of precipitation decreases among the Mexican states in the U.S.-Mexico border region (Montero Martinez et al. 2010).

• xii The projections of Seager and colleagues (2007) are based on GCM analyses of precipitation minus evaporation, from an ensemble of GCMs used in the IPCC Fourth Assessment Report. They note that projected changes in atmospheric circulation, which promote atmospheric stability and poleward expansion of the Hadley Cell, are factors that contribute to projected temperature-driven increases in evaporation and greater aridity.

• xiii Magaña, Zermeño, and Neri (2012), using statistically downscaled data from an ensemble of GCMs that use the high-emissions scenario, show large decreases in 24-month Standardized Precipitation Index (a measure of drought) and soil moisture during the second half of the twenty-first century in northwestern Mexico. Similarly, Gutzler and Robbins (2011), using statistically downscaled data from an ensemble of GCMs (SRES A1b) show large increases in the Palmer Drought Severity Index in the northern part of the border region; they note that “the projected trend toward warmer temperatures inhibits recovery from droughts caused by decade-scale precipitation deficits.”

• xiv Seager et al. (2009) note that this strong natural variability may obscure the development of increasing aridity that is occurring as the result of increasing temperatures and evaporation.

• xv See the Executive Summary above for confidence statements pertaining to this summary.

• xvi When effective, collaborative networks may become “communities of practice” that pursue new “adaptive pathways” — intentionally adaptive operations or strategies responsive to climatic change — in their respective institutions (Wilder et al. 2010). For a general discussion of the integral role of collaboration (e.g., trust, social learning, iterative interactions, common definitions of challenges) — not related to the border region, see Cash et al. 2003 and Pelling et al. 2008. Relating these aspects of collaboration to scientist-decision maker networks with the goal of co-production of science and policy, see Lemos and Morehouse 2005.

• xvii For a concise history of the border region, see Ganster and Lorey 2008.

• xviii The Wall Street Journal Online reported that 37% of net new jobs created in the U.S. since the economic recovery began were created in Texas (http://online.wsj.com/article/SB10001424052702304259304576375480710070472.html). Texas leads the nation in minimum-wage jobs (at 9.5% of total workforce) (CNNMoney, http://money.cnn.com/2011/08/12/news/economy/perry_texas_jobs/index.htm).

• ixx Source: U.S. Census Bureau FactFinder, http://factfinder.census.gov/servlet/DTGeoSearchByListServlet?ds_name=PEP_2008_EST&_lang=en&_ts=286892460001.

• xx For example, Tijuana, with a population of about 1.2 million, is heavily dependent on maquiladoras with over 600 plants (2002 data, GAO 2003) and is closely tied to the U.S. market.

• xxi Robertson (2009) notes that November 1, 2006, the Mexican government formally integrated the firms in the maquiladora industry into the PITEX program (Programas de Importación Temporal para Producir Artículos de Exportación), thus ending the practice of separating maquiladora trade from other manufacturing trade statistics. Beyond this date, statistics specific to maquiladora export are unavailable.

• xxii Much of U.S.-Mexico trade occurs between border states. For example, 62% of U.S. exports to Mexico originated in Texas, California, Arizona, and New Mexico; of this, 70% was destined for Mexican border states (GAO 2003). The total actual value of merchandise trade (exports and imports to and from the U.S. and Mexico) in 2008 was $367 billion — a 266% increase since 1994 (EPA 2011). Official data show that the four U.S. border states originated 58.8% of U.S. exports to Mexico (88.8 billion dollars), which is more than twice their 24% share of U.S. GDP (Bureau of Economic Analysis, Trade Stats Express). Retail sales contribute to GDP and economic interdependence at the border. Residents from Tijuana make 1.5 million trips per month into the San Diego area, mainly to shop. In El Paso, Juárez residents account for more than 20% of retail sales (GAO 2003). Cross-border tourism creates positive economic impacts in Arizona-Sonora (Pavlakovich-Kochi and Charney 2008) including jobs, retail sales, and tourism. Tijuana, El Paso, and Nogales, Arizona are all significant ports-of-entry for Mexican agricultural produce.

• xxiii Three treaties are of particular importance: the 1906 Water Convention on the Rio Grande River, the 1944 Water Treaty allocating water on the Colorado and Rio Grande Rivers, and the 1970 Boundary Treaty. The International Boundary and Water Commission (IBWC), established in its modern form by the 1944 Water Treaty, oversees implementation of these treaties and is charged with settling all disputes related to these agreements.

• xxiv Mexico has begun to decentralize and delegate some authority for water resources to regional watershed councils and the Mexican states. See Ley de Aguas Nacionales y su Reglamento. 1992 rev. Mexico, D.F.: Comisión Nacional de Aguas. Available at: http://www.conagua.gob.mx/CO-NAGUA07/Publicaciones/Publicaciones/Ley_de_Aguas_Nacionales_baja.pdf; OECD. 2003. Environmental Performance Reviews: Mexico. Paris: Organization for Economic Cooperation and Development, p. 20.

• xxv On the Mexico side of the region, inventories have documented the presence of 4,052 plant species; 454 species of invertebrates; 44 species of amphibians (mostly crustaceans); 184 species of reptiles; 1,467 species of birds; and 175 species of mammals (EPA 2011, based on Kolef et al. 2007).

• xxvi The Sierra Club’s “Wild Versus Wall” video (http://arizona.sierraclub.org/conservation/border/borderfilm.asp) illustrates the negative impacts on wildlife of the border fence.

• xxvii The Colorado River has its headwaters in the Rocky Mountains and passes through nine states in two countries, and through the tribal homelands of the Cocopah tribe in the U.S. and the Cúcapa in Sonora. Waters of the Colorado River were allocated in the 1944 Treaty, based on a high-flow year (1922). Under the treaty, the water is shared among seven U.S. basin states (California, Arizona, Nevada, Colorado, Wyoming, and New Mexico) and Mexico is guaranteed 1.5 million acre-feet annually. From its distribution point at the Imperial Dam in Yuma, Arizona, the Colorado River winds to the west and empties into the delta before a trickle (in some years) reaches the Gulf of California. The total watershed of the Colorado is 244,000 square miles. The Colorado River system supports nearly 30 M people along its 1,400 mile (2,250 kilometer) length, 120 miles of which are in Mexico. It irrigates 3.7 million acres of farmland, including 500,000 in Mexico. Major cities in the border region drawing on the Colorado for urban uses include San Diego, San Luis Río Colorado, and Mexicali. Major agricultural areas reliant on surface water from the Colorado include Imperial and Coachella Valleys, and San Luis Río Colorado and Mexicali irrigation districts. All told, more than twenty U.S. Native American tribes have rights to Colorado River water.

• xxviii No data are yet available on the impacts of AAC concrete-lining; however, experts have visually observed decreased flows (personal communication, 1/2012, A. Cortez-Lara).

• ixxx MacDonald (2010) notes in the U.S. West today these losses are already on the order of $2.5 billon/year.

• xxx In addition, the upper Rio Grande receives a trans-basin diversion from Reclamation’s San Juan-Chama project (on the Upper Colorado River) of about 94,000 acre-feet annually.

• xxxi The 2011–2012 agricultural programs for the Mexicali Valley and San Luis Río Colorado, after the reduced area due to the 2010 earthquake, are authorized to grow 72, 697 hectares of wheat, 32,064 hectares of cotton, and 27,251 hectares of alfalfa (SAGARPA, Delegación Estatal en Baja California, 2011).

• xxxii In late 2008 the Secretary of the Environment of the State Government of Baja California formed the PEAC-BC, an interdisciplinary research team that includes research institutes and universities of the region such as the UABC, CICESE, and COLEF. Their aims were to assess current and potential impacts of climate change in Baja California as well as to propose mitigation actions. For more information see http://peac-bc.cicese.mx.

• xxxiii The quantity of summer rain can be a major determinant of the number of head produced, but rain that is too heavy can waterlog pastures and wash out roads used to transport cattle to market (Coles and Scott 2009). Other weather and climate-related sources of vulnerability identified include heavy rains, winds, hail, lightning, and frosts (Coles and Scott 2009).

• xxxiv The annual cost of wildland fire suppression in California alone now typically exceeds $200 million (MacDonald 2010). Three simultaneous wildfires in San Diego County in October 2003 and another in October 2007 resulted in 25 deaths, destroyed a total of 3,700 homes, and scorched over 1,850 square miles (3,000 square kilometers) (Grissino-Mayer 2010).

• xxxv Approximately 1.1 million acres burned in New Mexico in 2011, more than 4.5 times the state’s average of around 242,000 acres. In Arizona, slightly more than 1 million acres burned, more than 5.5 times the state average of about 182,000 acres). Dry conditions desiccated soils and live fuel sources (e.g., grasses, shrubs, and trees) by the spring and a hard February freeze killed many plants and contributed to the fuel build-up (Southwest Climate Outlook, Oct. 25, 2011).

• xxxvi The Colorado River Water Delta Trust has identified a minimum base flow need of 63 mcm (51,000 acre-feet). The Trust has acquired 1.7 mcm (1,367 acre-feet), based on a successful collaboration between NGOs and the state of Baja California in securing treated effluent from Mexicali for environmental flows to the Rio Hardy (Zamora-Arroyo and Flessa 2009).

• xxxvii http://www.geimexico.org/english.html provides an overview of Mexican efforts.

• xxxviii See http://www.sandag.org/index.asp?projectid=235&fuseaction=projects.detail.

• ixl U.S. EPA, “Draft Border 2020 Document – for public comment – September 5, 2011,” lines 126–153.

• xl See http://www.tjriverteam.org.