Climate change could lead to unprecedented migration

Posted: 10 June 2009

Migration and displacement, caused by climate change, could vastly exceeds anything that has occurred before, according to a report launched today. Whole human populations may be forced to move for their own survival.

Climate change is already contributing to migration, with all major estimates projecting that the trend will rise to tens of millions of migrants in coming years says today's report by the UN University, CARE International and Columbia University.

The International Organisation for Migration (IOM) estimates that there may be 200 million environmentally-induced migrants by 2050. Within the next few decades, the consequences of climate change for human security efforts could be devastating.

Migrant, Ganges Delta
Migrant, Ganges Delta
In the Ganges Delta, living with varying water levels is a way of life. Migration, particularly towards coastal urban centres, has emerged as a coping mechanism when extreme events endanger life and livelihoods. With projected sea level rise, combined with the possibility of more intense flooding and storm surges, migration may become a necessity for many communities, at least for parts of the year. Photo © UNHCR
The new report, released during this week's Bonn Climate Change Talks under the United Nations Framework Convention on Climate Change, says that people in the least developed countries and island states will be affected first and worst. The consequences for the global economy and poverty reduction efforts could be devastating, with the possiblity of substantial implications for political stability.

The report, In Search of Shelter: Mapping the Effects of Climate Change on Human Migration and Displacement, is based on a first-time global survey of environmental change and migration. It is illustrated with a series of detailed maps that show how and where significant displacements may occur. Among its findings:

  • Breakdown of ecosystem-based economies including subsistence herding, farming and fishing will be the dominant driver of forced migration.
  • Climate change will increase the frequency and intensity of natural hazards such as cyclones, floods and droughts. Rains in parts of Mexico and Central America, for instance, are projected to drop as much as 50 per cent by 2080. Farmers in parts of Mexico and north Africa's Sahel region may already be moving in part due to changing rains.
  • Sea level rise directly threatens the existence of some 40 countries. Saltwater intrusion, flooding and erosion could destroy agriculture in the densely populated Mekong, Nile and Ganges deltas. A rise of two metres, or six feet - well within some projections for this century - would inundate nearly half the Mekong's 3 million hectares (7.5 million acres) of farmland. Some Pacific island nations including the Maldives (pop. 300,000) are already considering prospects for total relocation.
  • Ongoing melting of alpine glaciers in the Himalayas will devastate the heavily irrigated farmlands of Asia by increasing floods and decreasing long-term water supplies. The glacier-fed basins of the Ganges, Brahmaputra, Irawaddy, Salween, Mekong, Yangtze and Yellow rivers now support over 1.4 billion people.
  • Most migrants will probably move within their own countries, or to countries next door. Many will be poor, and many will be unable to move far enough to improve their lots. Ripples from resulting conflicts and collapses will hit richer countries.
Nile Delta sea rise map
Nile Delta sea rise map
Map shows the Nile delta, with sea level rises of 1 metre (dark blue) and 2 metres (light blue), along with population density (lighter to darker browns) and urban areas (hatching). Of the 40.2 million people here in 2000, 10.7 million would be inundated by a 2-metre rise. The inset shows the distribution of farmlands. Credit: Center for International Earth Science Information Network, Columbia University

Coauthor Charles Ehrhart, CARE's climate-change coordinator, called the potential impacts "startling."

"Societies affected by climate change may find themselves locked into a downward spiral of ecological degradation, towards the bottom of which social safety nets collapse, while tensions and violence rise," said a statement from CARE. "In this all-too plausible scenario, large populations would be forced to migrate as a matter of immediate survival."

Another co-author, Alex de Sherbinin, of the Center for International Earth Science Information Network (CIESIN) at the Earth Institute of Columbia University, pointed out that human population is projected to grow from 6.8 billion today, to 9 billion by 2050. "Countries are running out of places to put people productively," he said. "You can't just stockpile people."

"While human migration and displacement is usually the result of multiple factors, the influence of climate change in people's decision to give up their livelihoods and leave their homes is growing" adds Dr Ehrhart.

Declining rainfall

Mexico and the Central American countries are already experiencing the negative impacts of climate change - both in terms of less rainfall and more extreme weather, such as hurricanes and floods.

"The potential impacts of future sea level rise are at least as startling. In Vietnam's densely populated Mekong River Delta, for example, a sea level rise of two metres would - assuming current populations densities - flood the homes of more than 14.2 million people and submerge half of the region's agricultural land," says Ehrhart.

Map, sea level rise, Ganges delta
Map, sea level rise, Ganges delta
The main map depicts areas of sea level rise at 1 and 2 metres (dark and light blue, respectively) on a population density map with urban extents delineated. The Ganges delta supported a population of 144 million in 2000, out of which 9.4 million lived in areas that would be inundated by a 2 metre sea level rise. The top left inset map shows those areas most frequently impacted by tropical cyclones. Low elevation areas in the southeastern corner of the delta are most affected. The bottom left inset map depicts the area affected by the 2007 flood. The middle inset map shows the distribution of agricultural lands.
Most people will seek shelter in their own countries while others cross borders. Some displacement and migration may be prevented through the implementation of adaptation measures. However, poorer countries are underequipped to support widespread adaptation. As a result, societies affected by climate change may find themselves locked into a downward spiral of ecological degradation, towards the bottom of which social safety nets collapse while tensions and violence rise. In this all-too-plausible worst-case scenario, large populations would be forced to migrate as a matter of immediate survival.

"New thinking and practical approaches are needed to address the threats that climate-related migration poses to human security and wellbeing," says Dr. Koko Warner, Head of Section of the UN University's Institute for Environment and Human Security (UNU-EHS) and lead author of the report.

The report, 'In Search of Shelter: Mapping the effects of Climate Change on Human Migration and Displacement' is a joint product of the UN University's Institute for Environment and Human Security (UNU-EHS), CARE International and Columbia University's Center for International Earth Science Information Network (CIESIN). It can be downloaded here.