Global climate change is recognized as a threat to species survival and the health of natural systems. Scientists worldwide are looking at the ecological and hydrological impacts resulting from climate change. Climate change will make future efforts to restore and manage wetlands more complex. Wetland systems are vulnerable to changes in quantity and quality of their water supply, and it is expected that climate change will have a pronounced effect on wetlands through alterations in hydrological regimes with great global variability. Wetland habitat responses to climate change and the implications for restoration will be realized differently on a regional and mega-watershed level, making it important to recognize that specific restoration and management plans will require examination by habitat. Floodplains, mangroves, seagrasses, saltmarshes, arctic wetlands, peatlands, freshwater marshes and forests are very diverse habitats, with different stressors and hence different management and restoration techniques are needed. The Sundarban (Bangladesh and India), Mekong river delta (Vietnam), and southern Ontario (Canada) are examples of major wetland complexes where the effects of climate change are evolving in different ways. Thus, successful long term restoration and management of these systems will hinge on how we choose to respond to the effects of climate change. How will we choose priorities for restoration and research? Will enough water be available to rehabilitate currently damaged, water-starved wetland ecosystems? This is a policy paper originally produced at the request of the Ramsar Convention on Wetlands and incorporates opinion, interpretation and scientific-based arguments.

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Wetlands and global climate change: the role of wetland restoration in a changing world

The 2018 edition of the United Nations World Water Development Report stated that nearly 6 billion peoples will suffer from clean water scarcity by 2050. This is the result of increasing demand for water, reduction of water resources, and increasing pollution of water, driven by dramatic population and economic growth. It is suggested that this number may be an underestimation, and scarcity of clean water by 2050 may be worse as the effects of the three drivers of water scarcity, as well as of unequal growth, accessibility and needs, are underrated. While the report promotes the spontaneous adoption of nature-based-solutions within an unconstrained population and economic expansion, there is an urgent need to regulate demography and economy, while enforcing clear rules to limit pollution, preserve aquifers and save water, equally applying everywhere. The aim of this paper is to highlight the inter-linkage in between population and economic growth and water demand, resources and pollution, that ultimately drive water scarcity, and the relevance of these aspects in local, rather than global, perspective, with a view to stimulating debate.

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Reassessing the projections of the World Water Development Report

Inter-related and spatially variable climate change factors including sea level rise, increased storminess, altered precipitation regime and increasing temperature are impacting mangroves at regional scales. This review highlights extreme regional variation in climate change threats and impacts, and how these factors impact the structure of mangrove communities, their biodiversity and geomorphological setting. All these factors interplay to determine spatially variable resiliency to climate change impacts, and because mangroves are varied in type and geographical location, these systems are good models for understanding such interactions at different scales. Sea level rise is likely to influence mangroves in all regions although local impacts are likely to be more varied. Changes in the frequency and intensity of storminess are likely to have a greater impact on N and Central America, Asia, Australia, and East Africa than West Africa and S. America. This review also highlights the numerous geographical knowledge gaps of climate change impacts, with some regions particularly understudied (e.g., Africa and the Middle East). While there has been a recent drive to address these knowledge gaps especially in South America and Asia, further research is required to allow researchers to tease apart the processes that influence both vulnerability and resilience to climate change. A more globally representative view of mangroves would allow us to better understand the importance of mangrove type and landscape setting in determining system resiliency to future climate change.

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Impacts of climate change on mangrove ecosystems: a region by region overview

Claims have been made that global environmental change could drive anywhere from 50 to almost 700 million people to migrate by 2050. These claims belie the complexity of the multi-causal relationship between coupled social–ecological systems and human mobility, yet they have fueled the debate about “environmentally induced migration”. Empirical evidence, notably from a 23 case study scoping study supported by the European Commission, confirms that currently environmental factors are one of many variables driving migration. Fieldwork reveals a multifaceted landscape of patterns and contexts for migration linked to rapid- and slow-onset environmental change today. Migration and displacement are part of a spectrum of possible responses to environmental change. Some forms of environmentally induced migration may be adaptive, while other forms of forced migration and displacement may indicate a failure of the social–ecological system to adapt. This diversity of migration potentials linked to environmental change presents challenges to institutions and policies not designed to cope with the impacts of complex causality, surprises and uncertainty about social–ecological thresholds, and the possibility of environmental and migration patterns recombining into a new patterns. The paper highlights fieldwork on rapid- and slow-onset environmentally induced migration in Mozambique, Vietnam, and Egypt. Current governance frameworks for human mobility are partially equipped to manage new forms of human mobility, but that new complementary modes of governance will be necessary. The paper concludes with challenges for governance of environmentally induced migration under increasing complexity, as well as opportunities to enhance resilience of both migrants and those who remain behind.

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Global environmental change and migration: governance challenges.

The opinions expressed in this report are those of the authors and do not necessarily represent those of the UN University, CARE International, Columbia University, the UN Refugee Agency (UNHCR), or World Bank. Questions and comments are welcome and should be addressed to the primary authors Koko Warner (warner@ehs.unu.edu), Charles Ehrhart (ehrhart@careclimatechange.org), Alex de Sherbinin (adesherbinin@ciesin.columbia.edu) and Susana Adamo (sadamo@ciesin.columbia.edu). Media inquiries should be directed to media@careclimatechange.org and Sandra Bulling (bulling@care.de). CARE grants permission to all not-for-profit organizations to reproduce this work, in whole or in part. The following notice shall appear conspicuously with any reproduction: " In search of shelter: mapping the effects of climate change on human migration " Women and children displaced by floods, which had immeadiately followed a drought, in Northeastern Kenya Printed in an environmentally friendly manner. Acknowledgements This report and related activities advocating for the protection of environmental migrants are possible due to generous support from the UN Refugee Agency (UNHCR); the Cogan Family Foundation; and the World Bank, Social Development Department, Social Dimensions of Climate Change Team. We would like to acknowledge the EACH-FOR field researchers upon whose empirical work part of this report is based. We thank these contributing authors for their input in this report: Liège) performed her fieldwork in Bangladesh. We extend our thanks to Andrés González for map design (CIESIN, Columbia University), to Noel Lumbama for the report's design and other colleagues in academic, international organizations, civil society, and the public sector, as well as constructive feedback from the UNFCCC and other UN and intergovernmental organizations. We further appreciate the support provided by Sandra Bulling (CARE Germany), Susanne Ludwig (CARE Germany), Johanna Mitscherlich (CARE Germany), Sabine Wilke (CARE Germany), Michael Zissener (UNU-EHS), and colleagues at CARE Denmark and CARE International. We appreciate the generous cooperation of the City of Bonn (Maria Hohn-Berghorn) and the constructive dialogue with local partners and NGOs.

In search of shelter: mapping the effects of climate change on human migration and displacement.

The Mekong River delta plays an important role in the Vietnamese economy and it has been severely impacted during this century by a series of unusually large floods. In the dry season the delta is also impacted by salinity intrusion and tides. These effects have caused severe human hardship. To mitigate these impacts, a large number of engineering structures, primarily dykes and weirs, have been built in the delta in recent years and are still being built, mainly to control floods and saltwater intrusion. These control measures are still being upgraded. A GIS-linked numerical model shows that the flood levels in the delta depend on the combined impacts of high river flows in the Mekong River, storm surges, sea level rise, and the likely, future siltation of the Mekong Estuary resulting from the construction of dams in China as well as many other dams proposed throughout the remaining river catchment. The model suggests that the engineering structures in the delta increase the flow velocities in the rivers and canals, increasing bank erosion, and cause the water to be deeper in the rivers and canals. This increases flooding in the non-protected areas of the delta and increases the risk of catastrophic failure of the dykes in the protected areas. The model also predicts that a sea level rise induced by global warming will enhance flooding in the Mekong River delta in Vietnam, and that flooding may worsen in the long term as a result of estuarine siltation resulting from the construction of dams. At the scale of the Mekong River basin, a multinational water resources management plan is needed that includes the hydrological needs of the delta. At the scale of the delta, a compromise is needed between allowing some flooding necessary for agriculture and preventing catastrophic flooding to alleviate human suffering.

The combined impact on the flooding in Vietnam's Mekong River delta of local man-made structures, sea level rise, and dams upstream in the river catchment

Huu Nhan Nguyen

Papers

The combined impact on the flooding in Vietnam's Mekong River delta of local man-made structures, sea level rise, and dams upstream in the river catchment