Impact of Climate Change on Human Health and Health Economics: An Interview With Wendy Janssens

Guest Section Editor: Ágnes Benedict, MSc, MA, Evidera, Budapest, Hungary


Although climate change isn’t a new phenomenon, its impact on global health and health economics and health outcomes is only now making mainstream news headlines. This issue of  Value & Outcomes Spotlight examines global threats from climate change through a health economics and outcomes research (HEOR) lens, which presented a unique opportunity for me to speak to Wendy Janssens, PhD, a Professor in Development Economics at School of Business and Economics at Vrije Universiteit, Amsterdam, The Netherlands. She is an Academic Board member of the Amsterdam Institute for Global Health and Development (AIGHD), on the Health Economics Research Amsterdam management team, and research fellow at the Tinbergen Institute. She is also research advisor for PharmAccess Foundation.

Currently, she is leading an interdisciplinary research program on mobile technology and universal health coverage for mothers and children in Kenya, including the evaluation of maternal mental health interventions.

photo_JanssensValue & Outcomes Spotlight:
Climate change has been ongoing for a few decades now. Several of the consequences of rising temperatures and rising CO2 levels are already being experienced: there are severe droughts, flash floods, melting ice, and forest fires reported across the world with multiple health consequences.

You are a development economist. What made you interested in the topic of the impact of global climate change on health?

Wendy Janssens: My work focuses mostly on global health. In the past 10-15 years I’ve been working on access to healthcare and sexual and reproductive health, as well as on maternal and child health. At every single one of my research sites, I see how the people we are working with are affected directly by climate change. Let me provide a few examples.

In Pakistan (where we are doing a research study on child marriages), monsoon floods occurred at a large scale last year, with the poorest segment of the population—who were most likely to live in the areas with the greatest risk of flooding—were impacted most severely. About 1500 people died during the initial weeks. In addition to death risks, flooding also causes a lot of other health-related problems, such as infectious diseases outbreaks, mental health stress, or malnutrition due to damage to crops and livestock.

In Malawi, we witnessed a significant impact from an intense tropical cyclone Freddy that hit between February and March 2023. It was the most long-lasting cyclone ever recorded, persisting continuously for 5 weeks, going back and forth across Southern Africa. Malawi was the hardest hit, with 500 deaths and 500,000 people displaced. In the pediatric hospitals [where we were conducting our research at the time], children affected by flooding and mudslides were brought in with various injuries. There were also cases of cholera outbreaks.

"At every single one of my research sites, I see how the people we are working with are affected directly by climate change. "


Kenya and the entire region of the Horn of Africa (region including Kenya, Somalia, and Ethiopia) have been affected by a very severe drought over the past couple of years. As we were monitoring different infectious diseases in the West of Kenya, we noticed a real-time increase in the number of children being brought in with malnutrition symptoms. In the north of Kenya, the problem was even more severe.

In the current situation, my colleagues and I feel that it is crucial to incorporate climate change in our work on health and development because we are already in the middle of it. The devastating impact of climate change is going to overrule all the other health measures that we are undertaking if we do not manage to turn the tide now.

Much of your work is focused on health problems in the low- and middle-income countries in the Global South. What do you see for these regions in terms of the impact of climate change on population health in addition to the examples that you have given?

WJ: A major problem is that a lot of the countries in the Global South have had very little to do with causing climate change. For example, Africa has only contributed to 3% of the global carbon emissions. The contribution of most low- and middle-income countries to global climate change is small, but at the same time the impact on these countries is the largest. They are also the most vulnerable, as they possess limited resources to mitigate the consequences and to adapt to climate change. In addition, the poorest states are also the ones with the youngest population, who will be affected most by the impact in the future.

"The devastating impact of climate change is going to overrule all the other health measures that we are undertaking if we do not manage to turn the tide now."


This resonates with the study published in The Lancet Planetary Health that suggests larger anxiety caused by global climate change among young people aged 16 to 25 years.

WJ: Yes, I find the results of this study concerning. For this study, 10,000 young people (including children and adolescents) were interviewed in 8-10 countries. So far, there is very limited quantitative evidence about the perception of global climate change among young people. This was an online survey, meaning that their respondents had access to the Internet and were generally involved in current affairs, so in that sense there is a selection bias; however, the size of the study population is large. In this study, 60% of the respondents reported being “very”, or “extremely worried” about climate change—a substantial number.

It was clear from the comparison between the participating countries that the youth from countries in the Global South were most worried. These concerns were also related to the extent of help they were expecting from their government to cope with the effects. In countries like The Philippines, where an increase in the number of floods and cyclones is already being felt, this is reflected in an increased pressure on mental health and elevated stress and anxiety levels among young people. Similarly, pandemics may become more prevalent as well. In a recent study in PLOS Medicine, we show how COVID-19 significantly increased depressive symptoms in eight different low- and middle-income countries.

So far, only individual studies report data on consequences of these impacts of climate changes on human health. Coincidentally, on June 6, 2023, the WHO launched a consultation on the matter (REACH 2035). In addition, the Royal Netherlands Academy of Arts and Sciences (KNAW) released a report on Planetary Health: An Emerging Field to Be Developed. The report is a step ahead as it provides a list of research topics and questions. One of the issues raised there was the carbon footprint of healthcare itself. Do you think it would make sense to include environmental impact of healthcare in health technology assessments?

WJ: A 2022 paper in The Lancet Planetary Health suggested that the environmental impact of the healthcare sector is about 5% of the total carbon footprint, similar to that for the airline industry; within The Netherlands, this figure is even higher at 8%. The healthcare sector contributes a lot to water consumption, pollution, and waste generation, while less polluting solutions are available. 

What ongoing research do you have in this area (ie, carbon footprint and global warming)?

WJ: At the moment, a large research consortium is being set up across Africa to investigate the impact of heat-related stress on pregnancy and birth outcomes for pregnant women and newborn babies. This project will use data from my previous studies (among others) that assessed risk factors during pregnancy for maternal and child health and the potential of value-based healthcare in improving outcomes.

We are also developing a research program that will link fine-grained meteorological data on rainfall, droughts, and temperature to the occurrence of a large range of health outcomes, including both infectious and noncommunicable diseases. From existing studies, we know that these impacts may be large. For example, in Indonesia, a paper in the journal Health Economics found that on the days when the temperature reaches 30° Celsius or higher, visits to healthcare centers or hospitals increased by 8%. Visits associated with diabetes increased by even 25% and visits of patients with cardiovascular diseases increased by 14%.

With global warming, higher temperatures will become more prevalent, especially in tropical areas. Rates of noncommunicable diseases are also increasing, which means there will be a lot of additional pressure on healthcare systems due to climate change. In many countries, healthcare systems are highly vulnerable and urgently need strengthening.

Are there any issues you see there that have been exacerbated by climate changes in the last decade?

WJ: A critical issue to highlight is malnutrition that occurs due to the increasing rates of droughts and floods, but also during epidemic outbreaks such as when COVID-19 hit. Malnutrition has a long-lasting impact throughout an individual’s life. Children who experience chronic malnutrition at a young age may later suffer from cognitive delays, which will hinder their academic performance and attendance at school. This may also affect their productivity as an adult and result in a greater proportion of individuals with low income-generating capacity in the future. It thus creates a cycle of intergenerational poverty. Economic research has shown that even in-utero malnutrition can have long-lasting and severe impacts -- leading to weaker immune systems, physical and cognitive impairments, and greater susceptibility to non-communicable diseases as an adult.


"There is a gap in our understanding of how different aspects of climate change impact health. And while we are gaining knowledge in this area, we still lack a clear understanding of how to effectively address these effects."


A lot of progress that has been achieved in reducing malnutrition rates over the past decades may now be reversed due to the negative impact of climate change. How to mitigate these effects, for example by changing to more drought-resilient crops, is something we want to look into further.

There are several digital health interventions being tested by a non-governmental organization, PharmAccess Foundation, that you are partnering with. Could these be used to create an alert system that would send out notifications about approaching heatwaves and provide instructions on protective measures for people to undertake?

WJ: In high-income countries, these alert systems are well established. Especially for the more vulnerable populations (such as the elderly, pregnant women, and young children), there are plans in place that also activate various measures, including the opening of community centers equipped with air conditioning and ensuring sufficient water supply in towns during a heatwave.


"Africa has only contributed to 3% of the global carbon emissions. The contribution of the low- and middle-income countries to global climate change is very little, but at the same time the impact on these countries is the largest."


In many low- or middle-income countries, meteorological alert systems do not yet exist. However, implementing health-alert systems, even in a simplified form, could already benefit vulnerable populations. For instance, providing simple tips such as staying in shaded areas, drinking sufficient water, and avoiding strenuous activity during the hottest hours can go a long way in mitigating the effects of hot weather without requiring significant financial resources. It all begins with timely alerts to the population.

As we document in several recent publications, mobile technology can be of great value in this respect. For example, during the COVID pandemic, PharmAccess was running a digital maternal care program that registered pregnant women via their mobile phones. This program proved particularly beneficial during lockdowns as it enabled healthcare staff to easily contact women as required at each stage of their pregnancy. They could provide timely advice, and guidance on what to do or avoid. The convenience of this approach was helpful in supporting expectant mothers. Similarly, digital dashboards were developed that supported local governments in tracking and localizing outbreaks and vaccine uptake.

Nowadays, mobile phones are in widespread use and many individuals have access to mobile money applications. Digital tools can provide outreach and health services, and governments can leverage mobile technology to transfer cash and rapidly establish a social safety net for those in need. Mobile money eliminates the need for recipients to travel or possess a bank account, reaching people even in remote locations.

Still, there is a lot that remains for us to investigate. There is a gap in our understanding of how different aspects of climate change impact health. While we are gaining knowledge in this area, we still lack a clear understanding of how to effectively address these effects. Global warming is now increasing towards 1.5° Celsius and countries will increasingly encounter its consequences. What actions should countries take? Which interventions will have the greatest impact and will be at the same time cost-effective? Given limited resources, countries must strategically focus their efforts to address the vast problems at hand. There is much work to be done within a relatively short time frame, as time is running out to allocate resources towards interventions that will bring the greatest impact at the lowest cost.


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