City: | Mexico City |
Country: | Mexico |
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* This case study was written by the city and has not been edited by AIPH
Mexico City is one of the largest and most populated metropolises in the world. Despite having only an area of 1,494.3 km2, equivalent to 0.1% of the national territory (INEGI, 2020), it is home to 2% of world biodiversity and 12% of national biodiversity, 770 endemic species of plants and animals, and a great variety of species of corn, squash, chili, amaranth, and beans. This natural and cultural heritage comes both from urban areas (rivers, urban forests, ravines and parks), as well as from the more than 87 thousand hectares that are classified as “conservation land” that represent almost 60% of Mexico City’s territory (natural forests, thickets, rivers, wetlands and lands worked by rural communities).
Given the deterioration and loss of this heritage, caused by the disconnection with nature, the growth of the urban sprawl and factors such as overexploitation, pollution, changes in land use, invasive species and the effects of climate change that have generated, for example, conditions conducive to a greater incidence of fires, as of 2019 a comprehensive policy was launched to regenerate the ecological conditions of the city based on a vision of sustainability, innovation and rights, derived from the Government Program of Mexico City 2019-2024 and established in the Environmental and Climate Change Program (ECCP) 2019-2024.
The first of the axes of the ECCP refers to the “Revegetation of the countryside and the city”, which gave rise to the revegetation strategy called “Green Challenge”, within which the planting of 10 million trees and other plants between 2019 and 2020 was established as a quantitative goal, with a comprehensive approach that covers the following lines of work:
Thanks to the Green Challenge, the increase in the annual production of plants went from less than 500 thousand in 2018 to more than 10 million in 2021, which has allowed the planting of 27,082,593 trees and plants. The creation and rehabilitation of 16 large parks located mainly in peripheral areas with the greatest lack of access to public spaces, benefiting 6.3 million inhabitants. Additionally, 4,155 inhabitants of rural communities are benefiting in return for their work as brigade members in reforestation and ecological conservation activities, such as the plantation of 16.9 million plants only on conservation land, including the reforestation of 16,505 hectares in forests and rivers.
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The annual production of plants in Mexico City went from less than 500 thousand in 2018 to more than 10 million in 2021
Due to its geographical location and orographic characteristics, Mexico City is a system exposed to various climatic and hydrometeorological hazards. Because of anthropogenic factors such as overexploitation, expansion of the urban sprawl, changes in land use, soil, water and air pollution (the city emits 27 million tons of carbon dioxide equivalent) and the effects of climate change, the city faces problematic situations caused and intensified by the deterioration of ecosystems and the loss of its biodiversity.
There is a large amount of evidence on the intensification of the effects of climate change and the deepening of the conditions of the environmental problem in the city, which led to the establishment of very ambitious goals in 2019 to reverse these conditions, such as a 10% reduction in CO2equivalent emissions, compared to those produced in 2018.
The most important effects that directly impact the inhabitants have to do with material and human losses due to extreme rains, floods and landslides (between the years 2000 and 2015 there were 51 events of this type that affected 52,331 people), urban heat islands and temperatures extreme high temperatures that, combined with changes in rainfall patterns, generate conditions for a greater incidence of fires that contribute to the loss of ecosystems (from 2019 to 2020, the area affected by fires in conservation land had been reduced by 50% thanks to the increased resources for its attention, but in 2021 the affected area doubled due to a severe drought condition linked to the ENSO-Niña climatic phenomenon).
There is great evidence on the intensification of the effects of climate change and the environmental problems in the city that led to the establishment of much more ambitious goals in 2019 to reverse these conditions. Between 2000 and 2015, Mexico City registered a total of 66 hydrometeorological phenomena, whose impacts are the most costly and damaging due to the impacted extensions and the affected population. The most frequent were related to torrential rains and storms, landslides, low temperatures and strong winds, which caused damages of 1,173,876 million pesos (56 million dollars), affecting 11,107 homes and 64,655 people (Source: National Center for Disaster Prevention).
Also, from 1991 to 2020, 12,332 fires were registered in the city, 10.6% of the fires in the country (Source: National Forestry Commission) and the temperature in the urban area has increased up to 5°C with respect to the rural area in the dry season of the year and 4% with respect to its surroundings (mainly urban areas with cement and asphalt structures).
In the city there are 105 species in some category of risk and at the beginning of this century more than 70% of the extension of oak and pine-oak forests had already been lost (Source: CONABIO; http://200.12.166.51/janium /Documents/13054.pdf).
It’s estimated that for each urbanized hectare, the aquifers stop recharging 2.5 million liters per year, in a context in which the area built on conservation land from 2005 to 2015 increased an annual average of 2.67%, reaching 5,518.69 hectares in 2015 (Source: IG-UNAM/SEDEMA, 2017).
We decided to unite the city with nature, so we developed a Special Green Infrastructure Program (SGIP) that provides the city with adequate criteria and guidelines for incorporating and increasing accessibility to green areas and blue spaces (rivers, lakes, water channels and wetlands), with a focus on solutions based on nature and in accordance with the socio-environmental characteristics of the eight regions that were established:
The proportion of specimens per vegetal stratum that is necessary to achieve a better development of the plantations was technically defined. In the conservation land, a proportion of 85% of trees, 13% of shrubs and 2% of herbaceous and ground cover has been maintained, and a practically inverse proportion in urban land.
The planning of interventions is carried out considering the EGIP, the catalogue of species that was prepared in 2019 (based on the potential to generate pollination processes, strengthen soils, regulate climate and air quality, increase water infiltration, reduce hydrometeorological risks and resist the environmental conditions before anthropogenic activities) and the specific conditions of the site. On the conservation land, potential quadrants to be restored are identified considering:
The Special Green Infrastructure Program for Mexico City (SGIP) establishes the planning and strategic design of the interventions considering the following criteria: environmental aspects (type of climate, average annual temperature and precipitation, types of soil, altitude interval, land use and vegetation, presence of natural protected areas and green areas in the city), social (number of inhabitants, area of green area per capita, habitability index), risks aspects (hydrometeorological, geological and chemical-technological) and the principles of connectivity, accessibility, functionality and resilience.
This condition has been reflected in the diversity of intervened spaces, allowing natural forests, natural protected areas, ravines, rivers, wetlands and natural ecosystems to generate multiple socio-environmental benefits such as reducing atmospheric pollutants, increasing aquifer recharge, reducing risks from flooding and landslides, and provide habitat for wildlife; while other spaces with nature, such as parks and urban green corridors, also offer more accessibility to public spaces, reduce the effect of heat islands and reduce flooding.
One concrete example: the intervention of 2.07 hectares in Mexico City Ecological Park included components with positive ecological impacts (revegetation of 5,574 m2 with native species), as well as others with social benefits (rehabilitation of two kilometers of cycle paths, 60 solar lights and the opening of four viewpoints, one guardhouse and two permeable parking lots), benefiting 62,400 annual visitors.
It’s possible to, simultaneously, face the effects of climate change, counteract loss of biodiversity, promote urban resilience and contribute to well-being and the fulfillment of the human right to a healthy environment, water and public space.
The financial and logistical feasibility is based on the following conditions and actions:
The Green Challenge incorporates the directive of the current Government of Mexico City’s motto “City of Rights and Innovation” through:
Trans-sectoral and transdisciplinary work is essential for the effectiveness of interventions. The Green Challenge has involved the coordination of a large number of areas and specialists, more than 4 thousand brigade members from rural communities and neighbors, companies and organizations within the urban area:
Interventions have a very important social base in the planning, design, implementation, maintenance and evaluation processes.
Within the conservation ground:
In the 25 natural protected areas (21,709 hectares):
In urban areas:
The Green Challenge of Mexico City established the goal of planting 10 million trees and plants. To date, 27,082,593 have been planted. This was possible at the confluence of the coordinated effort of all sectors. In short, thanks to:
The Green Challenge began in 2019 with the goal of planting 10 million trees and other plants. However, more and more social and private actors have joined and have contributed to the planting of more than 27 million specimens. Each intervention arouses the interest of the inhabitants and sublocal governments in replicating the green areas. Coordination between authorities as a main element of the initiative has made the attention to these needs increasingly efficient.
Different strategies have made it possible to generate a positive change in the relationship between the inhabitants and their natural spaces, causing cascading actions associated with capacity building and revegetation of the city. They are between them:
The “green infrastructure” concept is of recent appearance in government agendas, and there are principles that make it a milestone for development planning, considering the increasing importance given to the natural environment, social impact and mitigation to climate change.
Mexico City is part of the Metropolitan Zone of the Valley of Mexico (ZMVM), in conjunction with parts of the State of Mexico and the state of Hidalgo. This region has socio-environmental and economic conditions that cannot be addressed in isolation. The State of Mexico created its first Green Infrastructure Plan in its capital (Toluca) and an historic collaboration with Mexico City will allow the rehabilitation of “Río de los Remedios” river (15.7 kilometers), which crosses territorial demarcations in both territories. The SGIP has also motivated the creation of a management program based on Green Infrastructure in two southeast Mexican cities: Campeche (Campeche) and Mérida (Yucatán).
This strategy provides a systemic vision that can be adapted to each city, since it is based on a combination of global conditions (loss of biodiversity, ecosystems, climate change) and local elements that can be developed locally (classification by regions, selection of native species, involvement of all sectors).
To achieve comprehensive interventions with socio-environmental benefits, as well as the widest possible scope, given the depth of the environmental crisis, it is desirable a combination of priority interventions defined by the government and an open call to all sectors that creates incentives in a context in which the effort and recognition belongs to all.
The Direction of Climate Change and Sustainable Projects monitors and quantifies the impacts of the Environmental and Climate Change Program (ECCP) of Mexico City in each of its 7 axes (Revegetation of the countryside and the city, Rescue of rivers and water bodies, Sustainable water management, Zero waste, Integrated and sustainable mobility, Air quality and Solar city). In this sense, interventions for “Revegetation of the countryside and the city” are already contributing to mitigate 74,249 tons of CO2e per year.
In addition, the following actions contribute to reducing the carbon footprint:
Two of the principles on which the design of green infrastructure in the city is based are functionality and resilience. In addition to creating recreational, safe and comfortable spaces for people, green and blue spaces provide ecosystem services that help mitigate climate change, adapt and improve resilience. For this, the following aspects are considered:
On these bases, the interventions of the “Green Challenge” anticipate the expected impacts of climate change and seek to increase the recharge of the aquifer, reduce the risk of flooding, mitigate the urban heat island effect, recover and conserve the habitat of wild species (particularly those most vulnerable to climate change), increase the resilience of production systems inside conservation land and reduce the vulnerability of natural ecosystems.
Mexico City promotes a vision of circularity that is increasingly integrated into the production and consumption processes, which is reflected in the revegetation interventions that seek to reduce the extraction of natural resources, maintain a constant flow of these and manage them in a circularly way. Samples of this are:
This has made it possible to print a comprehensive and circular vision of resources, which contributes to the regeneration of natural sources and the recovery of essential resources for biological cycles.
The strengthening of the public policy framework and the integration of green infrastructure in urban planning instruments with a long-term vision were considered essential for the continuity and maintenance of interventions, for example:
The interventions carried out in the city are planned and evaluated through the combination of the following indicators:
The latter has been essential to know that the average of green area per inhabitant (GA/Ihab) in 2017 was 7.54 m² (below international recommendations) and there was a notorious territorial inequality (six municipalities with GA/Ihab of 15.4 to 9.6m² and 10 municipalities with a GA/Ihab of less than 8.5 m² in their urban area or even less than 3 m2). The interventions have taken this condition into account to territorially balance the natural spaces.
The Special Green Infrastructure Program is a living and comprehensive instrument that can be adapted to the conditions of each city, because it combines the local visions and integrates government, academic and organizational efforts at all stages of its development, depending on the local needs expressed by all of them:
This has allowed it possible to optimize resources, increase scope, improve coordination and increase the permanence of the actions carried out, for the regeneration of ecological conditions throughout the city.
Progress document of the Environment and Climate Change Program (English)
Paris Design Awards 2020 Winner Certificate (Santa Catarina Project)
Mexico City Climate Action and Biodiversity Strategy (includes summaries in English)
Special Green Infrastructure Program for Mexico City (complete program in Spanish)