US-Mexico Climate Cooperation at a Stalemate

Overview

Border Region’s Vulnerability

As extreme climate events intensify around the world, the U.S.-Mexican border region has emerged as particularly vulnerable.[1] Large climate variability is likely to become the new normal. This variability will, in turn, modify agricultural supply chains, impact food security and human mobility, and affect people’s health and well-being. Droughts and floods, such as those recently experienced in California and Texas, are expected to occur more frequently.[2] Among these climate-related concerns, air pollution is an increasing issue throughout the region, exacerbating already poor air quality conditions. The Chihuahuan Desert has seen a recent surge in frequency and intensity of dust storms. Borderland residents face daily exposure to dangerously high levels of air pollution — including gases and particulate matter — due to industrial byproducts and the rapid growth in commercial and noncommercial traffic at the border.[3]

Gaps in Transboundary Pollution Policy

From a transboundary policy perspective, a bilateral emissions monitoring and reduction plan is long overdue. While initiatives like the Border 2025 Program and the United States-Mexico-Canada Agreement (USMCA) outline actions to address cross-border air pollution, they lack the legally binding agreements and regulatory frameworks needed to mitigate emissions and bad air quality from increased industrial activity, traffic, trade, and other climate impacts.[4] New policies are needed to create a permanent framework for monitoring and improving air quality, which would facilitate transboundary information exchange and the development of a cross-border greenhouse gas (GHG) emission reduction strategy. The previously shared vision of building a climate-friendly business base across border states — from electric vehicles (EVs) to solar manufacturing and renewable energy generation — faces challenges due to political shifts and differing interests in binational climate initiatives.

Further efforts to define regional nationally determined contributions (NDCs) and climate mitigation plans are required, specifically transboundary policies that take advantage of established international agreements and climate finance resources.[5] Such efforts might, in turn, create opportunities for collaboration on climate action by sharing common ground on issues and solutions related to data sourcing and collection, knowledge transfer, technical support, and cooperation, particularly among border states along the southern U.S.-Mexico border, addressing pressing environmental and social concerns. A review of the Border 2025 program’s air quality action plan reveals the challenges ahead and some steps both countries have taken to address this important issue. However, it does not fully oversee the complex climate challenges and bad air quality impacts that are forcing borderland cities to adapt to ever-changing weather patterns and international trade negative externalities.

Conflicting National Climate Agendas

The Mexican government recently announced its intentions to update the National Climate Adaptation and Mitigation Plan, which would expand its emissions reduction goal to more than 35% by 2030, as well as its carbon-neutral goal — although its ability to fund such a plan is unclear.[6] Under the Biden administration, the U.S. made progress on decarbonization through the Inflation Reduction Act (IRA) and enhancing resilience to climate change under the Bipartisan Infrastructure Law (BIL). However, the current Trump administration is reversing this progress, arguing that environmental regulations hinder economic growth.[7] It favors construction and oil and gas drilling over green infrastructure and renewable energy development.[8]

Although tariffs, organized crime threats, and mass deportations now dominate U.S.-Mexico diplomatic discourse, the critical issue of managing air pollution along the common border remains. From a human rights perspective, the cyclical exposure to air pollution from cross-border traffic and other sources can create serious public health risks in vulnerable communities.[9]This highlights the importance of a bilateral plan to ensure residents’ right to a clean and sustainable environment and the need to acknowledge that climate impact inequalities must be prioritized in government decision-making processes.[10]

Challenges Lie Ahead

With the Trump administration slowing the pace of U.S. climate action, these decisions will likely have repercussions in new trade negotiations with Mexico as the USMCA is revised in 2025 and renegotiated in 2026. The U.S. had been scaling up its manufacture of clean energy items, largely financed by the IRA and the BIL: This supply chain growth will need to continue to grow for the nation to remain globally competitive beyond the current presidential term.[11]

With manufacturing expected to surge in the coming years, the demand for clean, competitively priced energy on both sides of the border will require close monitoring and control. Carbon taxing schemes such as the EU and Canada’s Carbon Border Adjustment Mechanisms (CBAMs) could incentivize the adoption of low-carbon solutions to remain competitive, despite targets of 35% clean energy conversion in Mexico by 2030 and 66% in the U.S by 2035.[12]

For now, plans such as the Border 2025 Environmental Program, multilateral agencies such as the North American Development Bank (NADBank), other institutions, and research centers are currently developing partnerships to standardize information sharing and data collection along the border to foster cooperation and more effective air quality policies in the region.[13] These organizations will be key in bridging conversations around climate and emissions issues that go beyond political rhetoric to protect the climate, air, water, and vulnerable communities in both countries.

Assessing Air Pollution Reduction Under Border 2025

The Border 2025 plan is a collaborative initiative between the U.S. Environmental Protection Agency (EPA) and Mexico’s Ministry of the Environment and Natural Resources (SEMARNAT) aimed at enhancing environmental protection and public health along the U.S.-Mexico border from 2021 to 2025. It establishes four main goals:

1. Reducing air pollution.
2. Improving water quality.
3. Promoting sustainable waste management.
4. Enhancing preparedness for environmental emergencies.[14]

The first goal, to reduce air pollution, is supported by five specific objectives to address emissions in the border region:[15]

• Air-Monitoring Networks — Establish sustainably operated, reliable monitoring networks to provide real-time access to air quality data.
• Emissions Data — Improve the quality and exchange of emissions data across the U.S.-Mexico border and among federal, state, local, and indigenous communities, and promote standardized approaches.
• Vehicle Emissions — Reduce vehicle emissions by establishing or strengthening programs that address noncompliant vehicles. This includes implementing vehicle inspection and compliance programs across the affected states.
• Reduction of Pollution — Deploy strategies and technologies that reduce pollutants and improve public health in the region.
• Climate Action Plans — Support the update and/or completion of climate action plans in the six northern Mexican border states by 2025. This includes building the capacity needed to ensure their sustained implementation.

To advance these goals, a number of binational initiatives have addressed air pollution across the U.S.-Mexican border, resulting in the following advancements.

Establishing Air Monitoring Networks

The establishment of air monitoring networks has advanced significantly. However, many existing monitoring stations still face challenges with reliability, functionality, and maintenance. Due to the limited number and placement of stations it is difficult to measure all pollutants and their sources across the entire borderland airshed. Nonetheless, some progress is being made as new data becomes available in the region.

• The Binational Air Quality Monitoring Network is a collaborative initiative between the U.S. and Mexico to monitor, share, and analyze air quality data in the border region.[16] This network is essential for identifying sources of pollution, evaluating health risks, and guiding cross-border environmental policies and enforcement efforts.
• In the Paso del Norte (PDN) region — the binational metropolitan area that spans the U.S.-Mexico border — Ciudad Juárez and El Paso have collaborated with the Universidad Autónoma de Ciudad Juárez (UACJ) and the University of Texas at El Paso to start operating a network of ceilometers.[17] Additionally, in partnership with the Joint Advisory Committee, they collaborated on a project to collect particulate matter (PM) data from school sites in both cities.
• Ciudad Juárez operates eight monitoring points as part of the Border 2025 program and a new air quality monitoring station was established in 2023 with the support of the Binational Air Quality Monitoring Fund, aiming to increase their monitoring network in the region by 33%.[18]
• On the western side of the border, the city of Nogales, Sonora, has implemented regular maintenance on its ozone (O3), PM 10 and PM 2.5 monitors to ensure this network is providing accurate data through the Arizona Department of Environmental Quality.[19]
• The EPA has provided PurpleAir sensor replacements for the Mexicali, Baja California network, which is currently supported by the EPA, California Air Resources Board (CARB), and the Border 2025 Program.[20]

Data Exchange Standards for Indigenous Communities

Standardized mechanisms have been established to ensure that Indigenous groups can monitor their air quality stations effectively.

• As a condition of receiving EPA grants for monitoring programs, the EPA requires tribes to submit their data to the Air Quality Monitoring System. Tribes also must develop Quality Assurance Project Plans (QAPPs) to ensure that they will comply with EPA regulations for monitoring and reporting air quality data. The EPA suggests that Tribes partner with successful monitoring operations to help identify the best technologies and practices.[21]
• The EPA also made efforts to standardize emissions inventories by hosting an online technical training event for Baja California and Chihuahua.[22]
• The EPA’s Office of Air and Radiation (OAR) and Office of Research and Development (ORD) developed an “Introduction to Air Sensors” training that is publicly available in both English and Spanish to help train people to collect standardized data.[23]

Examples of specific community projects include the following:

• In Akela, New Mexico, the EPA has worked with the Fort Sill Apache Tribe to establish a PM 2.5 sensor to contribute more data toward emissions databases.[24]
• The Ysleta del Sur Pueblo Tribe in Texas has partnered with the TCEQ, the EPA, and the University of Texas School of Public Health to get technical air quality training and contribute to air monitoring programs via their own monitoring station.[25]
• Individual monitoring sites have taken steps to integrate their data into local, binational networks, including the Ciudad Juárez, Chihuahua air monitoring data network that works jointly with El Paso, Texas and Doña Ana County, New Mexico.[26]

However, no data is available to determine the air quality experienced by Indigenous Peoples on the Mexican side of the border, such as the Kikapoo and Yaqui, in Sonora.

Reducing Vehicle Emissions

Ciudad Juárez-El Paso Area

As part of the Border 2025 action plan, cities with high air pollution, such as Ciudad Juárez, were required to implement and develop a Vehicle Emissions Inspection Program by 2023. The state of Chihuahua has increased their emissions inspections to twice a year for freight vehicles and public buses circulating within the city, however, not all vehicles in the municipality of Ciudad Juárez have yet been inspected, including the public transportation buses that are mainly responsible for the largest amount of emissions.[27] The large number of vehicles driving on unpaved dirt roads in parts of El Paso County and across the border in Juárez is also a significant source of dust in the region, contributing to the designation of both Ciudad Juárez and El Paso as highly polluted cities.

Tijuana-San Diego Area

Despite a significant reduction in emissions from light-duty vehicles (passenger cars) over the past decade due to stricter emissions standards, vehicle emissions along the Tijuana-San Diego border remain a significant concern.[28] While efforts have been made to improve the emissions inventory and vehicle fleet data through roadside remote sensing programs and by incorporating local data into the MOVES-Mexico emissions model, this progress is being undermined.[29] A significant issue is the ongoing presence of illegally-imported old U.S. vehicles — known as “autos chocolate” (a play on the Spanish word for crooked, “chueco”) — which typically have significantly higher emissions and place a great burden on air quality in border cities.[30]

Reducing Pollutants

To increase awareness about the public health effects associated with exposure to high levels of ozone and PM 2.5, Border 2025 funded an Air Quality Education program in Ciudad Juárez, El Paso, and the Rio Grande Valley through community workshops.[31] They used low-cost sensors to assess PM 2.5 and O3 concentrations in a local community center.[32] These programs are especially critical to the border area, as many low socioeconomic communities lack access to adequate health care services.[33] Such local-level initiatives lay the groundwork for broader regional and binational strategies by fostering public engagement, raising awareness, and generating community-level data that can inform policy decisions. Other federal and state-level collaborations provide examples of recent progress:

• In 2022, the EPA and SEMARNAT partnered to improve Mexican emissions data inventories to address transboundary air pollution under the Border 2025 Program. Initial efforts focused on refining Mexico’s 2018 emissions inventory for Baja California and Chihuahua, with plans to expand to more states.[34]
• In 2025, California Governor Gavin Newsom and Sonora Governor Alfonso Durazo Montaño signed a memorandum of understanding to collaborate on reducing their joint emission footprint.[35] Their agreement promotes joint work on clean energy and emission reductions, illustrating how state-level diplomacy can reinforce federal environmental goals and enhance public health on both sides of the border.

Borderland Cities’ Climate Action Plans

The six Mexican border states and their U.S. neighbors are, from west to east:

• Baja California — California.
• Sonora — Arizona.
• Chihuahua — New Mexico and Texas.
• Coahuila, Nuevo León, and Tamaulipas — Texas.

All these Mexican states currently have several cities with climate action plans in place. The Mexico border cities of Ciudad Juárez, Reynosa, Tijuana, and Mexicali —along with the U.S. border cities of San Diego, Calexico, and El Paso — have sustainability or climate action plans. Aimed at reducing GHG emissions, improving air quality, and enhancing climate resilience, each plan is tailored to the unique socioeconomic contexts, environmental conditions, and capabilities of the cities.[36]

Notably, since these plans do not always include metrics to measure improvement on climate action strategies, some municipalities, such as Ciudad Juárez and Tijuana have developed municipal resilience plans and have joined global networks for resilient cities. Many of these urban planning efforts focus on confronting challenges such as chronic water scarcity, cross-border pollution, social inequality, and extreme weather events. They also address acute, and increasingly common, shocks such as trade disruptions and sanitary crises.

San Diego’s 2022 Climate Action Plan (CAP) is unique in its ambitious goal to achieve net-zero emissions by 2035, with a focus on decarbonizing buildings, expanding renewable energy, and promoting sustainable transportation, showing interesting progress.[37]

One Step Forward, Two Steps Back

The latest data available demonstrates that in 2022, the U.S and Mexico emitted a combined total of 4,987.271 metric tons of carbon dioxide, with the U.S. accounting for about 92% of the combined emissions.[38] The Climate Action Tracker currently ranks Mexico’s climate progress as “critically insufficient” and ranks the U.S. as “insufficient” regarding the goals of the Paris Climate Agreement.[39]

The current dismantling of many U.S. federal programs and budget cuts for climate change and emission reduction programs will make progress difficult for local governments. These changes put at risk both clean air initiatives for border communities and groundbreaking projects that could make the U.S. competitive in green technology. In the short term, the consequences will affect developments in carbon capture and storage, geothermal and nuclear energy, critical mineral exploration, and trade policies. These measures are likely to worsen air quality, harm public health, increase energy costs, and leave communities less equipped to handle extreme weather events, exacerbating climate injustice and risk.[40]

President Donald Trump has restricted the development of new renewable energy infrastructure and the funding of EV manufacturers, offshore wind, and solar panels.[41] In contrast, Mexico seems to be prioritizing its climate agenda. The country’s plans include increasing renewable energy goals from 35% to 45% by 2030 and reducing its emissions on 347 MtCO2e (million tons of CO2 equivalent) through nature-based solutions.[42] As the 30th Conference of the Parties (COP30) approaches in November 2025, Mexico is also reviewing its NDCs, with a potential 10% increase for the 2030–35 period.

Mexico’s emissions currently exceed NDC commitments made in 2022. There is also the political will to analyze and decide if the carbon-neutral goal could be achieved by 2050 or later and consequently increase the use of renewable energies to 45% in 2030 with a mix of hydroelectric (14%), wind (7.9%), and photovoltaic power (8.4%).[43] The current administration’s Mexico Plan aims for EVs to account for at least 10% of national sales by 2030, by focusing on improving vehicle performance.[44]

What remains to be seen is how Mexico will finance this transition. Mexican scholars and environmental experts agree that President Claudia Sheinbaum’s Cabinet is among the most coordinated and competent in a long time, with members capable of advancing climate action.[45] Even so, these high-level officials will face a six-year term constrained by two major limitations: a country unwilling to raise money more efficiently and a lack of readily accessible global climate financing for straining economies like Mexico’s.[46]

Just over a third of Mexican states have begun implementing carbon and green taxing schemes. These states — CDMX (Mexico City), Colima, Durango, the state of Mexico, Guanajuato, Morelos, Querétaro, SanLuis Potosi, Tamaulipas, Yucatán, and Zacatecas — are taking this step in anticipation of future international trade policies aimed at emission reduction requirements.[47] This initiative is a proactive step for Mexico to prepare its industry for possible Carbon Border Adjustment Mechanisms (CBAMs) and advance its participation in emerging carbon markets. However, the country is not yet fully equipped to tackle the significant challenges of climate adaptation. This is largely due to deep internal policy misalignments that continue to favor fossil fuel-based energy, which directly contradicts Mexico’s national climate goals and clean energy policies.

Political Context for Binational Climate Action

The present political scenario leaves little room to address the importance of binational climate cooperation. Monitoring air quality and controlling border emissions are only two of the key issues that should be prioritized under a binational environmental agenda. Transboundary pollution — including air, water, and all types of waste — requires coordinated and regulated efforts, for which political will and binational momentum are presently lacking.

Nevertheless, the imperative to address climate challenges that affect both Mexico and the U.S. persists. Renewable energy infrastructure will be essential on both sides of the border to meet energy demands, and emission reduction remains a key priority for U.S and Mexico border communities. The implementation of climate-smart agriculture is a pressing issue in shared ecosystems, as it is essential for ensuring food security and supporting essential ecosystem services. Encouraging technology transfer to support Mexico’s infrastructure modernization on energy grids, water distribution, and accessibility will continue to be relevant in the binational environmental agenda.

The urgency for the U.S. and Mexico to address shared climate challenges remains high. Gaps in binational climate cooperation could result in long-term impacts on fragile border ecosystems, urban infrastructure, and residents — particularly the most vulnerable. Addressing these issues through coordinated policy and action will be critical to protecting border communities and shared resources.

Acknowledgments

A special thank you to Mirabela Kumar and Dyllan Lozano, who provided research support for this report.

Notes

[1] World Weather Attribution, “Extreme Heat Killing More Than 100 People in Mexico: Hotter and Much More Likely Due to Climate Change,” June 20, 2024, https://www.worldweatherattribution.org/extreme-heat-killing-more-than-100-people-in-mexico-hotter-and-much-more-likely-due-to-climate-change/.

[2] “Rio Grande Region Watershed Drought Information,” NOAA and National Integrated Drought Information System, accessed July 1, 2025, https://www.drought.gov/watersheds/rio-grande.

[3] The Hunt Institute for Global Competitiveness, University of Texas at El Paso, “Our Border Environment: Water and Air Pollution. The Economic Impact of a More Efficient US-Mexico Border,” Atlantic Council, February 26, 2023, https://www.atlanticcouncil.org/wp-content/uploads/2023/02/Our_Border_Environment_Water_-and_-Air_Pollution.pdf.

[4] The Border 2025 program is the latest version of a binational effort between the U.S. and Mexico to address environmental and public health issues in the border region (“Border 2025 Goals and Objectives,” U.S.-Mexico Border Program, U.S. Environmental Protection Agency [EPA], https://www.epa.gov/usmexicoborder/border-2025-goals-and-objectives).

[5] Nationally determined contributions (NDCs) are nonbinding national climate plans that outline a country’s goals to reduce greenhouse gas emissions, created as part of the Paris Climate Agreement in 2015 (“Nationally Determined Contributions [NDCs],” United Nations Climate Change, https://unfccc.int/process-and-meetings/the-paris-agreement/nationally-determined-contributions-ndcs).

[6] Secretaría de Medio Ambiente y Recursos Naturales, “Secretaria Alicia Bárcena anuncia que México fortalecerá su política climática” [Secretary Alicia Bárcena Announces That Mexico Will Strengthen Its Climate Policy], press release, October 24, 2024, https://www.gob.mx/semarnat/prensa/secretaria-alicia-barcena-anuncia-que-mexico-fortalecera-su-politica-climatica?idiom=es.

[7] Oliver Milman, “Trump Has Launched More Attacks on the Environment in 100 Days than His Entire First Term,” The Guardian, May 1, 2025, https://www.theguardian.com/environment/2025/may/01/trump-air-climate-pollution-regulation-100-days.

[8] “2024 GOP Platform: Make America Great Again!” RNC Platform — Donald J. Trump, July 8, 2024, http://bit.ly/3KxDvmd; Beckett and Quinn, “Trump Administration Cancels $8 Billion for Climate Projects in Latest Shutdown Cuts,” CBS News, October 1 2025, https://www.cbsnews.com/news/government-shutdown-climate-cuts-8-billion/.

[9] Penelope J. E. Quintana et al., “Risky Borders: Traffic Pollution and Health Effects at US-Mexican Ports of Entry,” Journal of Borderlands Studies 30, no. 3 (2015): 287–307, https://doi.org/10.1080/08865655.2015.1066697.

[10] John H. Knox, “A/73/188: Report of the Special Rapporteur on the Issue of Human Rights Obligations Relating to the Enjoyment of a Safe, Clean, Healthy and Sustainable Environment,” Office of the High Commissioner for Human Rights (OHCHR), July 19, 2018, www.ohchr.org/en/documents/thematic-reports/a73188-report-special-rapporteur-issue-human-rights-obligations-relating; Iniciativa Climática de México (ICM), Civil Society Engagement in the Nationally Determined Contribution Process: A Proposal from Civil Society to Increase Ambition Through a Climate Justice Approach, 2022, https://iniciativaclimatica.org/ndc/wp-content/uploads/2023/01/Un-propuesta-desde-la-sociedad-civil-INGLES-131222.pdf.

[11] Riki Fujii-Rajani and Sanjay Patnaik, “What Will Happen to the Inflation Reduction Act Under a Republican Trifecta?,” Brookings Institution, January 6, 2025, https://www.brookings.edu/articles/what-will-happen-to-the-inflation-reduction-act-under-a-republican-trifecta/.

[12] Sam Boocker and David Wessel, “What is a Carbon Border Adjustment Mechanism?” Brookings Institution, July 8, 2024, https://www.brookings.edu/articles/what-is-a-carbon-border-adjustment-mechanism/; Mexico submitted an unconditional emissions reduction target of 35% and a conditional target of 40% by 2030. The U.S. declared to reduce emissions from 61 to 66% below 2005 levels by 2035. NDC Partnership, “Submitted Emissions Reduction Targets for Mexico and the United States,” accessed July 1, 2025, https://ndcpartnership.org/country/mex and https://ndcpartnership.org/country/usa. 

[13] “Ideas on Common Sustainable Solutions,” NADBank Blog, https://www.nadb.org/es/esblog.

[14] EPA and Medio Ambiente, Border 2025 United States-Mexico Environmental Program (Final), May 6, 2021, https://www.epa.gov/sites/default/files/2021-05/documents/final_us_mx_border_2025_final_may_6.pdf.

[15] “Border 2025 Goals and Objectives.”

[16] “Binational Air Quality Fund,” Joint Advisory Committee — Comité Consultivo Conjunto (JAC-CCC), https://www.cccjac.org/binational-air-quality-fund.html.

[17] A ceilometer is a device that uses a laser to measure the height of clouds and can also measure the concentration of tiny particles like dust and pollution in the air (“Instrument: Ceilometer,” NASA | CASEI, https://impact.earthdata.nasa.gov/casei/instrument/Ceilometer/).

[18] Private interview with Adrian Vazquez, expert on air quality and border issues from Universidad Autónoma de Ciudad Juárez; “Binational Air Quality Fund.”

[19] EPA, Arizona-Sonora 2021–2023 Border 2025 Action Plan, May 2022, https://www.epa.gov/system/files/documents/2022-05/border2025-az-sonora-2021-2023-action-plan-2022-05.pdf.

[20] California Air Resources Board (CARB), “2023 AB 617 CARB Annual Progress Report,” July 2024, https://ww2.arb.ca.gov/capp/mdr/arpt/2023-ab-617-annual-progress-report; “Annual Report 2023,” California Climate Investments, https://www.caclimateinvestments.ca.gov/annual-report-2023.

[21] The Quality Assurance Project Plans (QAPPs) and functioning Air Quality Monitoring Systems remain under the jurisdiction of the EPA. Although funding cuts are anticipated, QAPPs are less likely to be directly impacted, because the plans function as a core procedural element of most federal grant and cooperative agreements, regardless of the administration in power. See also EPA, “Tribal Air and Climate Resources,” updated August 20, 2025, https://www.epa.gov/tribal-air.

[22] EPA, California-Baja California 2021–2023 Border 2025 Action Plan, May 2022, https://www.epa.gov/system/files/documents/2022-05/border%202025-ca-baja-ca-2021-2023-action-plan-2022-05.pdf. In the context of environmental policy and regulation, emissions inventories refer to a detailed list or database of all sources of a particular pollutant and the quantity of that pollutant each source emits.

[23] EPA and SEMARNAT, Border 2025 United States-Mexico Environmental Program: Highlights Report Summer 2024, December 2024, https://www.epa.gov/system/files/documents/2024-12/border-2025-u.s.-mexico-environmental-program-highlights-report-summer-2024.pdf.

[24] “Support for Environmental Assessment Grants for Tribes: Region 6,” EPA, accessed July 1, 2025, https://www.epa.gov/quality/support-environmental-assessment-grants-tribes-region-6.

[25] EPA, Guidance and Policy for Implementation of Tribal Air Monitoring Programs: Final, May 12, 2008, https://www.epa.gov/sites/default/files/2016-02/documents/internaltribal_monitoringguidancepolicyfinal51208_0.pdf.

[26] EPA, Border 2025 Action Plan (2021–2023) Texas–New Mexico–Chihuahua Region, February 26, 2023, http://bit.ly/4q8iWgo.

[27] Ciudad Juárez Municipal Government, “Vehicle Verification Program Presented in Support of Chamizal,” press release, July 25, 2025, https://www.juarez.gob.mx/noticia/26752/presentan-programa-de-verificaciA3n-vehicular-en-pro-del-chamizal.

[28] Eastern Research Group, Inc., “Vehicle Emissions and Fleet Characteristics in Baja California, Mexico: Final Report,” California Air Resources Board, February 13, 2023, https://ww2.arb.ca.gov/sites/default/files/2023-08/Baja_California_Fleet_Characterization_ERG_Final_Report_021323.pdf.

[29] “Mexico: Updated NDC 2022,” United Nations: Climate Change, https://unfccc.int/documents/624282.

[30] Tony Payan [with guests Guillermo Rosales Zárate and Juan Vega Gómez], “‘Chocolate Cars’: Illegal Vehicle Imports to Mexico From the US,” August 18, 2025, in Judy Ley Allen México Centered, podcast, MP3 audio, 40:00, Baker Institute Center for the U.S. and Mexico, https://www.bakerinstitute.org/research/chocolate-cars-illegal-vehicle-imports-mexico-us.

[31] EPA, Border 2025 Action Plan (2021–2023) Texas–New Mexico–Chihuahua Region, February 26, 2023, http://bit.ly/46LRwW1. 

[32] “Introducing the TCEQ Project,” Joint Advisory Committee — Comité Consultivo Conjunto (JAC-CCC), https://www.cccjac.org/uploads/9/1/9/2/91924192/presentation_1_introducing_tceq_project_2.pdf.

[33] EPA and Medio Ambiente, Border 2025 United States-Mexico Environmental Program Highlights Report, Summer 2024, December   2024, https://www.epa.gov/system/files/documents/2024-12/border-2025-u.s.-mexico-environmental-program-highlights-report-summer-2024.pdf.

[34] EPA, California-Baja California 2021–2023 Border 2025 Action Plan, May 2022, https://www.epa.gov/system/files/documents/2022-05/border%202025-ca-baja-ca-2021-2023-action-plan-2022-05.pdf; EPA, Border 2025 Action Plan (2021–2023) Texas–Coahuila–Nuevo Leon–Tamaulipas Region, February 24, 2023, http://bit.ly/4n15Uym.

[35] Governor Gavin Newsom, “California and Sonora Sign New Partnership Advancing Cross-Border Action for Cleaner Air and Clean Energy,” press release, March 17, 2025, https://www.gov.ca.gov/2025/03/17/california-and-sonora-sign-new-partnership-advancing-cross-border-action-for-cleaner-air-and-clean-energy/.

[36] Antonina Ivanova and Alba E. Gámez, Plan Estatal de Acción ante el Cambio Climático: Baja California Sur [State Climate Change Action Plan: Baja California Sur], Urban Climate Action Network, July 2012, https://uccrnna.org/wp-content/uploads/2017/06/2012_Baja-California-Sur_Plan-Estatal-de-Accio%CC%81n-ante-el.pdf; City of El Paso, El Paso Regional Climate Action Plan, March 1, 2024, https://www.elpasotexas.gov/assets/Documents/CoEP/Community-Development/Climate-Action/EP-Priority-Climate-Action-Plan-03.01.2024.pdf; City of San Diego, City of San Diego Climate Action Plan, 2022, https://www.sandiego.gov/sites/default/files/san_diegos_2022_climate_action_plan_0.pdf; Gobierno de México, Plan Estatal de Acción ante el Cambio Climático: Sonora [State Climate Change Action Plan: Sonora], August 2011, https://www.gob.mx/cms/uploads/attachment/file/164942/2011_son_peacc.pdf; Gobierno de Nuevo León, Estrategia de Acción Climática 2024–2027 [Climate Action Strategy 2024–27], 2024, https://www.nl.gob.mx/es/estrategia-de-accion-climatica-2024-2027; Gobierno de Tamaulipas, Anexo CXLI 111 del Plan Estatal de Cambio Climática de Tamaulipas [Annex CXLI of the State Climate Change Action Plan: Tamaulipas], https://po.tamaulipas.gob.mx/wp-content/uploads/2016/09/cxli-111-150916F-ANEXO.pdf; Instituto Metropolitano de Planeación de Tijuana (IMPLAN), Agenda Ambiental [Environmental Agenda], n.d., https://implan.tijuana.gob.mx/implan/agenda-ambiental.aspx; Municipio de Chihuahua, Plan de Acción Climática Municipal: Chihuahua [Municipal Climate Action Plan: Chihuahua], 2019, http://bit.ly/4o5X830; ONU-Habitat México, “Visión Juárez 2040,” 2025, https://onu-habitat.org/index.php/ciudad-juarez-2040; Pacto de Alcaldes – Latinoamérica, Análisis de Riesgos y Vulnerabilidades Climáticas: Mexicali [Analysis of Climate Risks and Vulnerabilities; Mexicali], March 2024, https://pactodealcaldes-la.org/wp-content/uploads/2024/03/8.-ARVC-Mexicali.pdf; Reynosa Ayuntamiento, Reglamento de Cambio Climático del Municipio de Reynosa, Tamaulipas [Climate Change Regulation of the Municipality of Reynosa, Tamaulipas], n.d., http://bit.ly/48jmTbB, Secretaría de Medio Ambiente (Coahuila), Plan Estatal de Acción de Cambio Climático: Coahuila [State Climate Change Action Plan: Coahuila], September, 2022, https://sma.gob.mx/wp-content/uploads/2022/09/Coahuila-PECC.pdf.

[37] Dorian Hargrove, “San Diego Climate Group Sues City over Climate Action Plan,” CBS 8, September 14, 2022, https://www.cbs8.com/article/news/local/san-diego-climate-group-sues-city-over-climate-action-plan/509-8980fa39-67e6-447b-b999-b23e969ca6d0.

[38] International Energy Agency (IEA), North America: Emissions, accessed July 2025, https://www.iea.org/regions/north-america/emissions.

[39] “Mexico,” Climate Action Tracker, December 12, 2022, https://climateactiontracker.org/countries/mexico/; “USA,” Climate Action Tracker, November 13, 2024, https://climateactiontracker.org/countries/usa/.

[40] Yessenia Funes, “Future of Justice40 Program Hangs in the Balance,” Voices for Environmental Justice, October 23, 2024, https://www.sej.org/publications/voices-environmental-justice/future-justice40-program-hangs-balance.

[41] Lisa Friedman et al., “Trump Wants to Unleash Energy, as Long as It’s Not Wind or Solar,” New York Times, January 21, 2025, https://www.nytimes.com/2025/01/21/climate/trump-energy-fossil-fuels.html.

[42] “Mexico: Updated NDC 2022,” United Nations: Climate Change, https://unfccc.int/documents/624282; see also Instituto Nacional de Ecología y Cambio climático (INECC), homepage, https://www.gob.mx/inecc. Nature-based solutions are mitigation strategies to sequester (capture and store) carbon from the atmosphere and reduce existing emissions that result from ecosystem degradation.

[43] “Mexico: Updated NDC 2022.”

[44] Mobility Portal Latino América, “Efecto Olinia. Plan México buscará aumentar 10% la producción de vehículos eléctricos a 2030” [Olinia Effect. Mexico’s Plan Aims to Increase Electric Vehicle Production by 10% by 2030], January 14, 2025, https://mobilityportal.lat/mexico-aumentar-vehiculos-electricos-2030/.

[45] Edith González Cruz, “El gabinete es el correcto, pero falta presupuesto: las deudas ambientales de México en 2024 y cómo luce el 2025” [The Cabinet Is Right, but the Budget Is Lacking: Mexico’s Environmental Debts in 2024 and What 2025 Looks Like], WIRED Medio Ambiente, December 31, 2024, https://es.wired.com/articulos/deudas-de-mexico-con-el-medio-ambiente-en-2024-y-como-luce-el-2025.

[46] Mexico collects the least taxes of all OECD countries. Its tax-to-GDP ratio was 17.7% in 2023 (“Revenue Statistics 2024 — Mexico,” OECD, http://bit.ly/3IiNj2s).

[47] Jessica García et al., Impuestos al Carbono en Estados Mexicanos [Carbon Taxes in Mexican states], MexiCO2: Plataforma Mexicana del Carbono, April 2021, https://www.mexico2.com.mx/uploadsmexico/file/carbonomx.pdf.

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