By: Joséphine Gantois, Anouch Missirian, Evelina Linnros, Anna Tompsett, Amir Jina, Gordon C. McCord, and Eyal G. Frank
Context
Across natural disasters, environmental challenges, and public health crises, many effects can be minimized with the right preparation. Systematic monitoring can be essential for identifying evolving risks early on, containing their expansion, and targeting investments that reduce harm and aid recovery. Conducting such monitoring can be very costly, especially when it cannot rely on passive detection, typical when pests are involved.
The study measures the economic value of one of the earliest and longest-running disaster monitoring systems—specifically, for the desert locust. The desert locust is one of the world’s most destructive agricultural pests. Even a medium-sized locust swarm consumes as much food per day as about 625,000 people. This poses a severe threat to food security across Africa, the Middle East and South Asia. For instance, wheat production in India is around 20 percent lower in years of locust upsurges.
Research Design
The study quantifies the benefits of locust monitoring using three decades of data to document how monitoring in remote breeding areas affects swarm outbreaks, how these swarms spread to populated areas, and how they affect children’s health. Measuring the value of monitoring systems when they are effectively preventing disasters is challenging because it is difficult to know what would have happened without them. In practice, monitoring systems are rarely maintained at peak effort and effectiveness, and the degree to which a community employs monitoring varies widely depending on government capacity and funding availability. As a result, the absence of recorded disasters and pest outbreaks may reflect weak monitoring rather than true absence of risk. This uneven monitoring effort across locations and time periods likely depends on perceived locust risk, which creates severe measurement error.
To overcome these measurement and inference challenges, the researchers first study how shocks to monitoring and control activities—using armed conflicts and rainfall shocks—affect outbreaks in breeding areas. Second, the authors use the fact that broad seasonal migration patterns are relatively predictable to map out the patterns of locust migration routes, connecting outbreaks in breeding areas to exposure in populated areas. Third, they use these data to estimate the effects of exposure to locust swarms on children’s health, measuring the impact on children’s height-for-age—the most reliable measure of lifelong impacts from past nutritional deficits.
Findings
Locust swarms increase when there is less monitoring. The study uses armed conflict as a way to track what happens when monitoring is impeded—finding that armed conflict prevents fieldworkers from conducting locust monitoring operations by 9.2 percentage points after a year of fighting. This reduced monitoring leads to a 2.9 percentage point increase in locust swarms. This effect is specifically observed under favorable breeding conditions: conflict always suppresses monitoring, but it leads to more locust swarms only when conflict co-occurs with large rainfall events that are essential to successful breeding.
Children exposed to locust swarms are more likely to experience stunted growth. Locust swarms decimate vegetation in their path, thereby destroying crops and pastureland and leading to local food shortages. With less food, children see their growth stunted. Children exposed to locust swarms in utero are 18 percent more likely to experience stunted growth (severely low height-for-age score), and 21 percent more likely when exposed in the nine months after birth. For those children exposed before birth, their risk of dying before age five increases by 16 percent.
The benefit of the locust monitoring system significantly outweighs its costs. The authors estimate that the increase in stunting, absent current monitoring actions, would result in long-term impacts on productivity, decreasing a country’s GDP by 0.35 percent on average or $25 billion per year. In other words, the benefit of maintaining monitoring is $25 billion per year, while the monitoring system cost $37-$77 million per year to implement. This implies a benefit-cost ratio of between 160:1 and 680:1 from improved childhood nutrition alone. This is likely an underestimate since it does not count agricultural profits or other benefits.
Closing Take-Away
The locust and its monitoring system serve as a case study for other disaster prevention efforts—especially valuable as climate change increases both the intensity and variability of many disasters, including pests and disease outbreaks. These disasters share common needs, like the need for international coordination and early warning systems. Additionally, they share funding challenges. For example, investments tend to fluctuate according to the perceived risk, causing the funding there is to go towards crisis response instead of prevention. This points to the need for data to better pinpoint where disasters are more likely to occur in order to prepare before they strike by investing in comprehensive monitoring and control efforts.
Case Study
The most recent locust outbreak occurred in 2019 during the Yemen civil war. Before the war, locust monitoring was consistent. But during it, large spikes in conflict led to gaps in reporting. Around 445,000 additional children experienced stunting due to these monitoring failures, with 83 percent of those cases spilling over into neighboring countries. This example illustrates how localized breakdowns in early warning systems can quickly escalate into regional health crises, affecting vulnerable populations far beyond national borders.