Aunque los movimientos causados por factores ambientales son diferentes según el contexto, algunas tendencias permiten preparar respuestas eficaces y sostenibles. Por ejemplo, la migración por motivos ambientales tiende a seguir las rutas migratorias ya existentes.

Dada la diversidad de situaciones, no existe un conjunto de enfoques de política ya preparado que sea adecuado para todos los casos de movilidad humana causada por desastres y por el cambio ambiental. Las respuestas de política tienen que adaptarse a los tipos de fenómenos ambientales y migratorios de cada lugar y momento particular.

Al mismo tiempo, las respuestas de política deben ser suficientemente amplias para abarcar todo el espectro de la movilidad humana (incluidas las personas que no migran). Como se examina más a fondo en el tema siguiente, las políticas alcanzan su máxima eficacia cuando conectan a diferentes sectores y niveles de gobernanza, y se aplican simultáneamente en el marco de un enfoque integral y coordinado. De hecho, la migración por motivos ambientales tiene vínculos con diversos ámbitos de política, como la reducción del riesgo de desastres, la respuesta humanitaria, la planificación del desarrollo, la ordenación del medio ambiente y la adaptación al cambio climático.

Las opciones de política que aquí se presentan tiene por objeto ayudar a los responsables de la formulación de políticas a determinar los enfoques proactivos ante los diversos retos y oportunidades.

Formas de minimizar y afrontar el desplazamiento

Las personas pueden verse obligadas a partir por un desastre repentino o por un fenómeno de evolución lenta. La mayoría de los desastres se producen en contextos frágiles, en que la degradación de los recursos ambientales y naturales aviva conflictos latentes o ya existentes, y en que los efectos de las amenazas son más graves y duraderos para los sectores más vulnerables. Las medidas de reducción del riesgo de desastres y de adaptación al cambio climático pueden atenuar el impacto de las amenazas naturales y antropógenas en las poblaciones humanas, reduciendo así el riesgo de desplazamiento, o mitigando sus repercusiones, cuando se produce.

El fortalecimiento de los medios de subsistencia es un modo fundamental de aumentar la resiliencia de las comunidades vulnerables ante los retos ambientales, y suele ser una parte importante de la adaptación al cambio climático, sobre todo (aunque no exclusivamente) en las zonas rurales. Las medidas pueden incluir la introducción de variedades de cultivos adaptadas a las condiciones locales, el fomento de una diversificación sostenible de los ingresos o la capacitación en las competencias adecuadas.

Las medidas de preparación para casos de desastre ayudan a reducir la probabilidad de que los desastres, cuando ocurran, generen una situación de vulnerabilidad aguda para los desplazados. Los elementos clave de la preparación para casos de desastre son los sistemas de alerta temprana, los planes de evacuación y la acumulación de existencias (el aprovisionamiento estratégico preventivo para una emergencia). Además, hay muchas maneras de contribuir a que las respuestas humanitarias presten una asistencia eficaz a las poblaciones desplazadas. Véase la información más detallada sobre la prevención y la preparación, la respuesta humanitaria y las soluciones duraderas al desplazamiento que figura en el capítulo Prevención, preparación y reducción de riesgos.

Policy Approaches
Addressing interconnections between displacement, the environment and climate change

The UNFCCC Task Force on Displacement (2018b) recommended that States consider:

  • Adopting national and subnational legislation, policies, and strategies that recognize disasters, the adverse effects of climate change and environmental degradation as drivers of migration;
  • Enhancing research, data collection, risk analysis, and information sharing;
  • Strengthening preparedness, including early warning systems, contingency planning, evacuation planning and resilience building strategies and plans;
  • Integrating human mobility challenges and opportunities into national planning processes;
  • Assisting internally displaced persons;
  • Facilitating orderly, safe, regular and responsible migration and mobility of people affected by the adverse impacts of climate change, as appropriate and in accordance with national laws and policies.

To optimize efforts to minimize and address displacement induced by environmental disasters, consider development-focused measures, including those proposed by UNFCC Task Force on Displacement:

  • Including disaster risk reduction (DRR) as part of national adaptation programmes of action (NAPAs) for climate change and as part of humanitarian action, particularly with respect to building back better;
  • When needed, providing livelihood support to give individuals and communities the means to invest in better quality homes or material to help protect homes during disasters, such as floods and storms;
  • Incorporating DRR in country poverty reduction strategy papers, national development plans and donor country assistance strategies/plans

On disaster risk reduction, the Sendai Framework for Disaster Risk Reduction provides useful guidance:

  • Engage with relevant stakeholders, including […] migrants […] in the design and implementation of policies, plans and standards (Paragraph 7).
  • Empower local authorities, as appropriate, through regulatory and financial means to work and coordinate with […] migrants in disaster risk management at local level. (Paragraph 27(h).
  • Develop initiatives to engage migrants and draw on their knowledge, skills and capacities in the design and implementation of disaster risk reduction, for instance to improve the resilience of communities and societies. (Paragraph 36(a)(vi)).
  • Develop measures to prepare for and adequately manage disaster-induced human mobility (both within and across national borders) in order to reduce the impacts of hazards: (Paragraph 36(a)(vi)).
  • Promote the mainstreaming of disaster risk assessments into land-use policy development and implementation, […] and the use of guidelines and follow-up tools informed by anticipated demographic and environmental changes. (Paragraph 30(f)).
Fuente

UNFCCC Conference of the Parties (COP), 2018b; Sendai Framework for Disaster Risk Reduction 2015–2030, 2015.

To Go Further

In view of the complex patterns of movement and complex vulnerabilities resulting from sudden- or slow-onset disasters, MCOF combines IOM humanitarian activities and migration management services in 15 sectors of assistance, and covers pre-crisis preparedness, emergency response and post-crisis recovery.

Facilitación de la migración para la adaptación al cambio ambiental

Hay datos que indican que la emigración de las zonas de riesgo o afectadas por desastres o por factores de estrés ambiental puede ayudar a las familias y comunidades a prevenir y afrontar los efectos de las amenazas ambientales y a recuperarse de ellos (Oakes y otros, 2019). Hasta ahora, pocos países han considerado específicamente la posibilidad de facilitar la migración voluntaria como medida de resiliencia y adaptación. Como se señaló en la sección sobre la migración en el contexto del cambio ambiental del presente capítulo, en las situaciones de desastre y de cambios ambientales la migración puede ayudar a:

  • reducir el número de personas expuestas a las amenazas locales;
  • reducir el uso de los ecosistemas locales y los recursos naturales y las presiones a que están sometidos, especialmente cuando el estrés ambiental es un problema;
  • diversificar y fortalecer los medios de subsistencia (Melde y otros, 2017; Warner y otros, 2012; Foresight, 2011);
  • disponer de remesas que se inviertan de maneras que reduzcan el riesgo y refuercen la resiliencia ante el cambio ambiental y climático;
  • tener acceso a redes distantes que puedan prestar apoyo y asistencia en caso de necesidad;
  • tener acceso a oportunidades de educación y mejora de las cualificaciones profesionales, lo que puede respaldar las prácticas de adaptación a corto y largo plazo en las zonas de origen mediante la transferencia de conocimientos y el cambio cultural.

La facilitación de la migración (por ejemplo, mediante programas de enseñanza de nuevas competencias) puede incluir actividades para facilitar la migración autónoma, el diseño de intervenciones que faciliten y apoyen específicamente los movimientos (por ejemplo, programas de migración laboral temporal y circular) o la aplicación de medidas que maximicen los beneficios que la migración reporta a los migrantes y a sus familias (por ejemplo, reduciendo los costos del envío de remesas) (TransRE, 2017).

Debería existir un conjunto de políticas destinadas a facilitar la decisión de migrar. Sin embargo, este ha de ser un enfoque equilibrado, que tenga en cuenta:

  • los posibles costos sociales de la migración, como la fuga de cerebros y los efectos de la “mano de obra perdida” en las comunidades de origen (véase, por ejemplo, Schade y otros, 2016);
  • que las respuestas de política encaminadas a facilitar la migración por motivos ambientales deben estar integradas en enfoques más amplios de la migración, ya que esta tiene, en la mayoría de los casos, múltiples causas, y los factores ambientales pueden ser difíciles de determinar.
To Go Further

Skills training

A significant constraint to migration from areas most exposed to environmental stressors, especially in rural settings, is the lack of education and skills to access alternative employment. New skills can help would-be migrants undergo the journey and/or adjust in the destination.

Strengthening education systems and access to vocational training is thus an indirect but potentially effective way to facilitate migration as adaptation. Interventions can be targeted to benefit particularly vulnerable groups (such as trapped populations, or pastoralists) and areas (for instance, drylands, mountain regions, or low elevation coastal zones).

Facilitating internal mobility

As in the case of international migration, facilitating internal migration pathways can help populations move away from areas exposed to risk.

The main challenges for policymakers in rural–urban migration are in the policy areas of urban planning and social cohesion. Many people moving away from environmental pressures are moving to cities where they are subject to other environmental risks such as landslides and flash floods (Foresight, 2011). Some of the world’s fastest-growing cities are located in low-lying coastal areas where sea-level rise brings additional threats, such as inundation, salinization of groundwater, and increased exposure to storm surges.

Moreover, large-scale rural–urban migration can overwhelm existing resources and cause urban expansion into areas subject to environmental risk. Insufficiencies relating to land-use planning, housing availability, public infrastructure (such as water availability, electricity, roads) and access to public services may disproportionately affect migrants. The clearing of forests for informal settlements in urban peripheries that serve as ecological buffer zones can increase exposure to environmental risks such as flooding and landslides. This will pose challenges for regions with relatively high urbanization rates, notably sub-Saharan Africa and Asia.

Policies that ensure

Article / Quotes

that migrants’ livelihoods are not more fragile than the established population could allow better integration in local society and provide migrants with opportunities to build up secure economic livelihoods, enabling transformation of the local economy. 

Fuente

Foresight, 2011: 182.

Moreover, migrants can “circulate” between rural and urban environments, maintaining strong ties with families in the rural home area (see more on Circular migration in Phases of migration). This type of migration, which is prevalent in many countries in Africa and Asia, can have a significant impact on building resilience to environmental and climate change and, in the longer term, positively impact development in (often rural) origin areas. Resilience is a key concept here, which if well defined, can be used across policy domains of migration, development and the environment.

Good Practice
Climate-resilient and migrant-friendly urban areas in Bangladesh

One way of facilitating migration pathways is by creating attractive cities. In Bangladesh, both governmental and non-governmental stakeholders identified existing urban areas throughout the country to turn them into climate-resilient migrant-friendly cities and towns. This aimed at anticipating and easing increased urbanization pressure on Dhaka due to the expected arrival of people avoiding negative impacts of climate change. Preparing cities and towns to receive migrants requires investment in both social aspects, such as addressing prejudice of the receiving community towards migrants, and physical aspects, such as the provision of livelihood options and housing, among other services.

Fuente

IOM (internal source); Shafiqul Alam et al., 2018.

Further details on facilitating internal mobility in the systemic migration-sustainable development nexus.

Facilitating international migration

While less frequent than internal movements, international movements are likely to become increasingly important in the longer term, especially at the regional level. In situations in which people are unable to adapt where they are, or in which return is not possible after disasters, it will be crucial for migration management to include strengthening regular migration pathways. This is recognized in objective 5 of the Global Compact for Migration, “Enhance availability and flexibility of pathways for regular migration”, together with objective 2 on “natural disasters, the adverse effects of climate change, and environmental degradation”. There are a number of policy areas that can be explored to provide regular and safe pathways for people impacted by environmental change.

Regional inter-State agreements facilitating the mobility of people across borders (often as part of broader regional integration frameworks facilitating mobility of goods, capital and, to varying degrees, services) can be very relevant for environmental migration, even if they do not target environmental migrants specifically. (For an introduction, see bilateral and multilateral agreements and regional initiatives in Initiatives and commitments addressing migration.)

Example
Protocol on Free Movement of Persons in the Intergovernmental Authority on Development Region

The Protocol on Free Movement of Persons in the region of the Intergovernmental Authority on Development (IGAD), including eight countries in the Horn of Africa, Nile Valley and Great Lakes subregions was adopted in February 2020 in Khartoum (Sudan). It grants the community’s citizens the right to enter, reside and establish themselves in the territory of Member States. While informal cross-border movements within the region have been a common feature – including as a response to drought – the formalization of mobility provides more secure access to rights.

Regional transhumance agreements are important in some regions. In the case of pastoralists, the effectiveness of traditional mobility strategies is being increasingly put to the test when faced with the impacts of climate change (recurrent drought, land degradation), land-use restrictions and encroachment on grazing lands (IOM, 2010). Regional transhumance agreements facilitate the cross-border movement of herders and their livestock.

Example
Regional transhumance agreements

The Economic Community of West African States (ECOWAS) International Transhumance Certificate is a sort of laissez-passer for herders and breeders which also includes measures to protect the rights of non-resident herders and receiving communities and establishes conflict mediation structures. Its legal basis is the 1998 Decision A/DEC.5/10/98 regulating transhumance between the Member States of ECOWAS.

Bilateral or inter-State temporary and circular labour migration (TCLM) schemes which target vulnerable populations in areas affected by hazards and environmental change could be used as a resilience and adaptation measure, though there are likely to be limitations in scale.

Good Practice
New Zealand’s Recognised Seasonal Employer scheme

New Zealand operates a seasonal migration scheme called the Recognised Seasonal Employer (RSE) scheme, allowing employers in the horticulture and viticulture sectors to hire seasonal workers from a selected number of Pacific countries. The RSE scheme was launched in 2007 with a cap of 5,000 workers, but due to growing demand the cap has been increased year on year, reaching 12,850 in 2018. The RSE scheme does not specifically target those within the participating Pacific countries who may be most vulnerable to climate change or other environmental change, but it does focus on climate-vulnerable countries and with a development-supporting objective.

Studies commissioned by the New Zealand authorities have found evidence of a development impact in the countries analysed (Samoa, Tonga, Vanuatu), with high percentages of income sent home in the form of remittances, and significant usage of remittances for investment in housing and education. These studies also found that a significant number of respondents reported having learned new skills abroad which would help them in establishing business enterprises in their home countries.

Fuente

Government of New Zealand, Ministry of Business, Innovation and Employment, n.d.

Non-reciprocal inter-State agreements can also facilitate mobility responses to environmental stressors. For example, New Zealand operates a Pacific Access Category (PAC) immigration scheme, whereby 75 people from Kiribati, 75 from Tuvalu, 250 from Fiji and 250 from Tonga may immigrate to New Zealand each year. These are among the countries most vulnerable to climate change in the world.

Current migration channels and agreements can also be used to absorb environmental migration, meeting the labour demands of destination countries and facilitating adaptation in countries of origin (Asian Development Bank [ADB], 2012). It is unlikely any such framework would specifically target environmental migrants; however, such agreements are ways of providing regular pathways and options for those facing severe environmental change.

Migration (or more specifically, “immigration”) laws, policies and practices have also been used by States in a case-by-case and flexible manner to facilitate migration for people affected by environmental hazards (Cantor, 2014). As one example, in 2012 the United States granted low-skilled work visas to selected Haitians as a support measure following the 2010 Haiti earthquake (Cooper, 2012). Similar practices include visa schemes that are implemented with a protection angle, such as the humanitarian visa schemes and family reunification visa schemes implemented by Canada. The Government of Chile provides a recent example, introducing family reunification visas for Haitian nationals through its new migration policies in 2018. People affected by environmental hazards, even though not specifically targeted, can largely benefit from the opening of this regular migration channel.

National immigration and visa schemes therefore should be taken into account when discussing the facilitation of regular migration from countries affected by environmental hazards. During humanitarian crisis situations, immigration and admission laws require flexibility to provide for the admission of persons who do not fulfil the normally applied admission criteria. Objective 5 (g) of the Global Compact for Migration recognizes this by encouraging measures such as: “humanitarian visas, private sponsorships, access to education for children, and temporary work permits, while adaptation in or return to their country of origin is not possible.”

In addition, several countries have temporarily suspended deportations and return of nationals of countries hit by disasters, though this has been on an ad hoc basis, and usually limited to nationals already present on the destination State’s territory prior to the disaster. After the 2004 tsunami, for example, the Canadian, Malaysian and Swiss governments temporarily suspended involuntary returns of asylum seekers whose application had been rejected to affected areas of India, Indonesia, Sri Lanka and Thailand (IOM, 2009).

Disasters often result in the activation of national emergency laws, which grant special powers and change the normal order of procedures. Knowledge of these national frameworks is important for the management of disaster displacement.

Policy Approaches
Measures that facilitate international migration

Enhance availability and flexibility of pathways for regular migration, for instance by:

  • Developing regional inter-State agreements facilitating the mobility of people across borders, such as regional transhumance agreements for pastoralists;
  • Developing non-reciprocal inter-State agreements, for example on labour migration;
  • Developing temporary and circular labour migration (TCLM) schemes;
  • Applying flexible enforcement of immigration laws or providing humanitarian visas and other temporary visa options to facilitate entry or stay for nationals of countries affected by disasters;
  • Including migration policy planning in national emergency response framework planning;
  • Temporarily suspending returns and deportations to affected countries;
  • Cooperating to identify, develop and strengthen solutions, including by devising planned relocation and visa options, in cases where adaptation in or return to the country of origin is not possible for migrants.
Fuente

United Nations General Assembly, 2018 (Global Compact for Migration objectives 2 and 5).

Facilitating remittance and skills transfers

Remittances are also a mechanism for building the resilience of households facing hazards and environmental change, through increased income, income diversification and risk management.

Since most migration in the context of environmental stress is expected to be internal, internal remittances must be considered, despite the lack of available data. While international migration is usually an expensive undertaking, remittances from diaspora communities tend to be correspondingly higher than internal remittances. Increased remittances in the wake of disaster often arrive faster than public assistance, providing vital funds for meeting basic needs and recovery.

Outside the context of disasters, remittances can provide funds for meeting basic needs when livelihoods are rendered less productive by environmental change, such as when climate variability leads to reduced crop yields. Furthermore, remittances can be invested in ways which may specifically improve resilience to environmental shocks and stresses, such as strengthening flimsy housing or purchasing drought-resistant crop seed varieties. Encouraging the optimal use of remittances can be combined with other programmes targeting adaptation to environmental change via migration, for instance by promoting skills transfer in relevant fields (such as water supply management or agriculture), including through engaging diaspora members and returning migrants.

Good Practice
Use of remittances in resilience building

Use of remittances for infrastructure and services to address impacts of environmental and climate change

A survey of forty migrant organizations in several regions in France, mostly founded following the 1970s drought in Senegal, investigated the contribution of the Senegalese diaspora to water development in Senegal. The results showed that some organizations collected fees for a “water fund” and migrant organizations had fully financed 70 per cent of all water projects back home. Almost seven out of ten organizations had funded at least one water project between 1996 and 2000. In addition, the organizations provided funding towards services such as education and health (Champetier and Drevet, 2000: 125).

Use of skills transfer in building resilience

Young, professionally-trained returnees contributed to environmental initiatives by bringing knowledge and skills in areas such as the environment, disaster management, technology, natural resources and crops to countries in the Senegal River valley (Mauritania, Senegal and Mali) (Scheffran, Marmer and Sow, 2012: 119–127). In India, seasonal internal migrants from agricultural areas in the eastern state of Jharkhand bring back skills in modern farming techniques from their work in the Punjab and Haryana areas (Deshingkar, 2010).

Further details on the importance of Remittances and ways to facilitate them can be found in The focus on migrants' assets.

Planned relocation

Planned relocation can be an effective pre-emptive measure to manage environmental risk. In contexts where permanent outmigration or recurrent displacement is not preventable in the medium to long term (and may involve the risk of populations becoming trapped), planned relocation can be an effective measure for reducing the exposure of vulnerable populations. It can be applicable to high-risk areas both in urban and rural settings, in the face of slow environmental change processes and acute or recurrent disasters.

However, there is general agreement in research and international policy circles that relocations should be a last resort once other options have been exhausted, due to the complex challenges involved, including:

  • They are very costly;
  • They have the potential to deplete the human, social and economic capital of both relocated and receiving communities, thereby causing impoverishment and further vulnerability;
  • Determining the point at which land becomes uninhabitable can be contentious, with differing definitions and perceptions of habitability;
  • Re-establishing livelihoods at the destination, in a different geographical context, might be difficult;
  • Maintaining social cohesion and avoiding cultural dislocation throughout the process is complex;
  • Ensuring that the rights of the affected communities are respected, both those being relocated and the receiving communities, can be difficult.

Even before the move, simply encouraging people to move may be challenging. Financial loss in the context of a relocation could be exacerbated by informal tenure (legal ownership) frameworks, which make it difficult to sell property. Hence, insufficient compensation can be an important consideration leading to the decision to stay. Populations that decide to stay behind remain vulnerable and increasingly exposed to environmental stressors.

There are already a number of examples of relocations linked to sea-level rise, such as in Fiji (see box below), the Gunayala islanders in Panama, and São Tomé & Príncipe, where governments are assisting communities in low-lying coastal areas to move to safer locations nearby (for more information on case studies, consult the Toolbox on Planned Relocation). Confronted with thawing permafrost and the loss of sea ice, the Alaskan village of Newtok is planning to begin relocation to a nearby site (Bronen, 2011). These have so far been limited to internal relocations (usually to nearby islands with higher elevation), but international relocation could potentially be needed in the future if worst case environmental change scenarios become reality. International relocation poses a whole range of operational and cultural challenges and raises some highly complex and controversial questions about national sovereignty if a State’s territory has disappeared.

Planned relocation within States is likely to become increasingly used as a last resort measure to move people away from areas subject to severe and irreversible environmental degradation or increasingly frequent or intense natural hazards.

Good Practice
Sea-level rise and planned relocation in Fiji

High exposure to sea-level rise and extreme events in Vunidogoloa (located on the second largest island of Fiji) led to a relocation process that was begun in 2006, with assistance from the Government and international organizations. The selection of the destination site was made by the people being relocated, a factor that was deemed critical to the relocation’s success. Fiji developed a national policy on planned relocation in the context of climate change in 2018.

Fuente

Tronquet, 2015.

International guidelines for relocation in the context of disasters and environmental change were recently developed by a consortium of agencies and academic institutions, following consultations with States (UNHCR, Brookings Institute and Georgetown University, 2015). The Toolbox for policymakers complementing the guidelines defines the approach that should be taken in terms of cross-cutting elements and stages of the process (UNHCR, IOM and Georgetown University, 2017).

Policy Approaches
Planned relocation design

Cross-cutting Elements

  • Element 1: The legal framework
  • Element 2: Needs of, and impacts on, affected populations
  • Element 3: Information, consultation and participation
  • Element 4: Land
  • Element 5: Monitoring, evaluation and accountability

Stages:

  • Stage 1: Making the decision that a planned relocation is needed (are there no alternatives?)
  • Stage 2: Preparing and developing a plan for planned relocation
  • Stage 3(a): Implementation: pending physical relocation
  • Stage 3(b): Implementation: during and following physical relocation
  • Stage 3(c): Implementation: longer term following physical relocation

Past experiences and success stories demonstrate that adequate participation of communities (origin and destination) in the decision-making process and long-term support of their livelihood options (such as site selection, development of compensation packages, grievance and appeals mechanisms) are essential in designing and implementing successful relocation plans.

To Go Further
Mensajes clave
  • Los objetivos generales de la política son reducir al mínimo los desplazamientos, prestar asistencia cuando ocurren, y facilitar la migración como estrategia escogida para fortalecer la resiliencia.
  • Se precisan esfuerzos concertados en todos los niveles para combatir las causas básicas de los desastres y el cambio ambiental, mitigar sus repercusiones a fin de minimizar los factores que obligan a las personas a migrar, contribuir a fortalecer la resiliencia, y lograr que las personas puedan permanecer en las comunidades con las que, en muchos casos, tienen fuertes lazos culturales y sociales. 
  • El aumento de las vías de migración regular y segura facilitará la migración como estrategia de adaptación. Para lograr ese aumento pueden utilizarse las políticas nacionales y acuerdos internacionales, pero también los programas de migración laboral ya existentes, aunque no estén destinados explícitamente a los migrantes por motivos ambientales. Además, en los casos de desastre los países pueden flexibilizar la aplicación de sus leyes de inmigración.
  • Las remesas se pueden canalizar hacia el fortalecimiento de la resiliencia, y la colaboración de las diásporas también ha sido muy provechosa; por lo tanto, pueden mejorarse las políticas para que faciliten en mayor medida el envío de remesas y la colaboración con las diásporas en el aumento de la resiliencia.
  • La reubicación planificada es una iniciativa sumamente difícil que solo debería utilizarse como último recurso. Cuando sea necesaria, deberá emprenderse con el consentimiento informado y la participación de las comunidades afectadas (incluidas las de la zona de destino).
AnteriorNexo entre migración y medio ambienteSiguienteConexión de las políticas para hacer frente a la migración por motivos ambientales