The impact on human health of restoring degraded African drylands
Lead Research Organisation:
London School of Hygiene & Tropical Medicine
Department Name: MRC Unit The Gambia at LSHTM
Abstract
This multi-country project aims to establish the health benefits of large-scale land restoration in Africa's Sahel region. We will leverage the Great Green Wall (GGW) of Africa initiative, the largest land restoration effort in the world, as a natural experimental system. Drylands host nearly 40% of the global population. The GGW and other similar land-restoration efforts currently underway around the world are set to reshape landscapes and the lived experiences of billions of people globally. Such restoration efforts are increasingly being regarded as potential 'Nature-based solutions' as the world seeks to confront and adapt to the triple challenges of climate change, biodiversity loss and food security.
At present however, human health considerations play a very minor role in the design and implementation of restoration projects, including the GGW. This project aims to fill this critical gap, to ensure restoration projects can maximally serve human health alongside other objectives.
We will use a novel combination of activities spanning 4 integrated work packages to do this. Briefly, WP1 will comprise a literature review and community consultations to develop an iteratively refined, gender-sensitive logic model describing the causal linkages between dryland restoration and human health. This will guide the project by helping to refine key hypotheses and identify a suitable subset of secondary health outcomes to be evaluated in subsequent WPs.
In WP2 we will collate as much existing data as possible for GGW countries to conduct a Sahel-wide village-matched health impact evaluation. The primary outcome to be investigated will be weight-for-age z score (WAZ) of children (0-59 months) as a measure of acute nutritional status. A subset of secondary outcomes in children and women emerging from WP1 as of particular relevance will also be considered. We will compare health outcomes between communities with and without GGW activities to evaluate the health impacts of restoration.
WP3 will be a follow-up of WPs1-2 in which we will conduct a more targeted, community-prioritised, village-matched health impact evaluation with primary data collection in three focal countries (The Gambia, Senegal, Burkina Faso). Based on our current understanding of the linkages between health and environmental restoration, these are likely to include other anthropometric measures (e.g., height-for-age z score, HAZ), and outcomes reflecting risk factors on the nutrition, infection and mental health / well-being pathways. We will again focus on children and non-pregnant women. Some secondary outcomes require collection of biological samples from children for laboratory analysis. Follow-up sampling will give information on seasonal effects and an opportunity to compare child growth over a 12-14 month period between groups with and without GGW interventions.
WP4 comprises a set of integrating tasks aimed at marrying the results of the health impact evaluations with current activities guiding the design and implementation of the GGW and understanding the role of and benefits to health of completing the GGW. With an anticipated cost of around $50 billion to reach its 100 million hectare target of restored drylands by 2030, it is essential for health impacts (benefits and costs) to be brought into existing decision-support tools for applied purposes. We will do this via a combination of steps from health economic evaluation, cost-benefit and trade-off analysis, and systems and scenario modelling in the context of a changing climate.
In all WPs, our Project Partners and Scientific Steering Committee will further ensure local relevance and streamline the research-to-practice pipeline, enhancing impact.
At present however, human health considerations play a very minor role in the design and implementation of restoration projects, including the GGW. This project aims to fill this critical gap, to ensure restoration projects can maximally serve human health alongside other objectives.
We will use a novel combination of activities spanning 4 integrated work packages to do this. Briefly, WP1 will comprise a literature review and community consultations to develop an iteratively refined, gender-sensitive logic model describing the causal linkages between dryland restoration and human health. This will guide the project by helping to refine key hypotheses and identify a suitable subset of secondary health outcomes to be evaluated in subsequent WPs.
In WP2 we will collate as much existing data as possible for GGW countries to conduct a Sahel-wide village-matched health impact evaluation. The primary outcome to be investigated will be weight-for-age z score (WAZ) of children (0-59 months) as a measure of acute nutritional status. A subset of secondary outcomes in children and women emerging from WP1 as of particular relevance will also be considered. We will compare health outcomes between communities with and without GGW activities to evaluate the health impacts of restoration.
WP3 will be a follow-up of WPs1-2 in which we will conduct a more targeted, community-prioritised, village-matched health impact evaluation with primary data collection in three focal countries (The Gambia, Senegal, Burkina Faso). Based on our current understanding of the linkages between health and environmental restoration, these are likely to include other anthropometric measures (e.g., height-for-age z score, HAZ), and outcomes reflecting risk factors on the nutrition, infection and mental health / well-being pathways. We will again focus on children and non-pregnant women. Some secondary outcomes require collection of biological samples from children for laboratory analysis. Follow-up sampling will give information on seasonal effects and an opportunity to compare child growth over a 12-14 month period between groups with and without GGW interventions.
WP4 comprises a set of integrating tasks aimed at marrying the results of the health impact evaluations with current activities guiding the design and implementation of the GGW and understanding the role of and benefits to health of completing the GGW. With an anticipated cost of around $50 billion to reach its 100 million hectare target of restored drylands by 2030, it is essential for health impacts (benefits and costs) to be brought into existing decision-support tools for applied purposes. We will do this via a combination of steps from health economic evaluation, cost-benefit and trade-off analysis, and systems and scenario modelling in the context of a changing climate.
In all WPs, our Project Partners and Scientific Steering Committee will further ensure local relevance and streamline the research-to-practice pipeline, enhancing impact.
Technical Summary
Large-scale land restoration initiatives, such as Africa's Great Green Wall (GGW), are being implemented to mitigate climate change, preserve biodiversity, and enhance sustainable development. Although evaluation studies have documented environmental and socio-economic benefits of land restoration, there is a large gap in knowledge concerning the human health impacts.
This research aims to address this gap, using the GGW as a large "natural experiment".
First, we will develop a "logic model" to map causal pathways linking human health and land restoration in drylands. We will do this by conducting a systematic literature review, consulting experts and holding community focus groups in areas where GGW activities have been implemented (WP 1).
Second, we will conduct a Sahel-wide health impact evaluation of GGW interventions. Data will be compiled from existing sources. A village-matched staggered difference-in-difference analysis will be used to compare health outcomes (primary outcome: WAZ) through time in sites with and without GGW activities (WP 2).
Third, we will conduct a detailed village-matched health impact evaluation in three focal countries. A household survey of children (0-59 months) and women (15-49 years) will be conducted. Anthropometric measurements and biological samples (children only) for laboratory analyses (e.g., for heat exposure, infection or nutrition indicators) will be taken. Cohorts exposed or not to GGW activities will be compared and followed up twice, covering a dry, a wet and a second dry season (WP 3).
Fourth, the health impacts of the GGW will be incorporated into existing cost-benefit analyses being used to enhance the benefits and implementation of the GGW. We will combine health economics assessment with a system dynamics model and scenario analyses to assess changes in health benefits through time under different implementation and global change scenarios (WP 4).
This research aims to address this gap, using the GGW as a large "natural experiment".
First, we will develop a "logic model" to map causal pathways linking human health and land restoration in drylands. We will do this by conducting a systematic literature review, consulting experts and holding community focus groups in areas where GGW activities have been implemented (WP 1).
Second, we will conduct a Sahel-wide health impact evaluation of GGW interventions. Data will be compiled from existing sources. A village-matched staggered difference-in-difference analysis will be used to compare health outcomes (primary outcome: WAZ) through time in sites with and without GGW activities (WP 2).
Third, we will conduct a detailed village-matched health impact evaluation in three focal countries. A household survey of children (0-59 months) and women (15-49 years) will be conducted. Anthropometric measurements and biological samples (children only) for laboratory analyses (e.g., for heat exposure, infection or nutrition indicators) will be taken. Cohorts exposed or not to GGW activities will be compared and followed up twice, covering a dry, a wet and a second dry season (WP 3).
Fourth, the health impacts of the GGW will be incorporated into existing cost-benefit analyses being used to enhance the benefits and implementation of the GGW. We will combine health economics assessment with a system dynamics model and scenario analyses to assess changes in health benefits through time under different implementation and global change scenarios (WP 4).
