USAID Mekong ARCC in collaboration with ICEM and a team of scientists and researchers have conducted the Climate Change Adaptation and Impact Study to assess the vulnerabilities to Lower Mekong livelihoods, communities, and ecosystems, and to downscale the climate modeling to support project replication throughout selected sites.
Assessing Threats to Lower Mekong Livelihoods, Communities, and Ecosystems
The U.S. Agency for International Development Mekong Adaptation and Resilience to Climate Change project (USAID Mekong ARCC) is conducting a Climate Change Adaptation and Impact Study that will assist in addressing key knowledge gaps of how climate change will affect livelihoods, communities, and ecosystems in the Lower Mekong Basin (LMB).
The USAID Mekong ARCC Study will provide accessible climate change impact scenarios for government and community decision makers, identifying key agricultural, fisheries, and ecological vulnerabilities and the connections between them. Clearly articulated sectoral vulnerabilities from the Study will assist these government and community leaders in making informed decisions that strengthen resilience to the consequences of climate change.
Climate Trend and Threat Modelling – The Study Methodology
The USAID Mekong ARCC Study team has developed a modelling approach to define and quantify the changes in hydro-meteorological variables over time, and to apply changes in the global climate system down to zones at a subnational scale across in the LMB. These factored changes include incidence, magnitude and duration of events such as floods, storms, rainfall-runoff relationships, evapotranspiration, and temperatures. Three geographical scales will be considered: (i) global, (ii) Mekong Basin, and (iii) Mekong ecozones sharing common bio-physical characteristics such as Meteorology, Hydrology, Ecosystems, Land use, and Agriculture systems.
The USAID Mekong ARCC Study will apply six Global Circulation Models (GCMs) under the Intergovernmental Panel on Climate Change (IPCC) Emissions Scenarios. GCMs approximate general circulation of the planetary atmosphere and are widely applied for weather forecasting, understanding climate, and projecting climate change at a large scale. The six selected were chosen based on their ability to most accurately replicate daily historical temperature and rainfall data. GCM output is compared to observed information from a reference period of 1980-2005 to calculate period factors.
(ii) Lower Mekong Basin
Since GCMs operate at coarse resolution, they are not appropriate for spatial assessments at basin, national or subnational levels. A statistical technique, which assumes local climate is conditioned by global climate but does not try to understand physical causality, used by the USAID Mekong ARCC project downscales global information to a Mekong Basin scale. An Integrated Water Resource Management Hydrological model will then utilize data from 151 precipitation stations and 61 temperature stations on the Lower Mekong to understand how climate change will alter hydrologic processes and forecast future changes in the movement, distribution, and quality of lower Mekong River water resources. The hydrological models will projects changes in: rainfall, runoff, flows, infiltration, evapotranspiration, crop productivity and patterns.
(iii) Mekong Ecozones
USAID Mekong ARCC’s approach to zoning identifies areas in the LMB with common bio-physical and socio-economic characteristics, and projects temperature, rainfall and other “shifts” in these areas expected to result from global climate change. Corresponding impacts on biodiversity and ecosystem services; agriculture, aquaculture, fisheries and livestock production; and food security and livelihoods will be determined and described for each zone. The relative level of vulnerability of a zone, and areas and species within it will be assessed considering the following factors:
- significant climate change relative to base conditions
- exposure to new climate/hydrological conditions
- limited temperature and moisture tolerance range
- degraded and/or under acute pressure
- severely restricted geographic range
- rare or threatened
- Adaptive capacity
- socioeconomic metrics
- population dynamics
The result of the assessment process will be the demarcation of areas highly vulnerable to climate change. Using this information, USAID Mekong ARCC will develop a set of options for community-based integrated adaptation interventions that link agriculture, animal husbandry, and fisheries sectors with ecosystems. These focal areas will be targeted for the implementation of the USAID Mekong ARCC Community and Ecosystem-based Adaptation Field Demonstration Sites, which will be initiated upon completion of the Study. The figure above represents the decision tree the USAID Mekong ARCC team employed to analyze the suite of available modeling options, and ultimately define the Study methodology.