The International EcoHealth Forum 2008 took place in December 2008, in Mérida, Yucatán, México. With 689 participants, it marked an important milestone in strengthening ecohealth research and building partnerships between researchers, practitioners, policymakers, and civil society organizations.
Read a summary of the first plenary session that focused on climate change.
Dr Jonathan Patz
Global Environmental Health, University of Wisconsin (Madison), United States
Dr Leonora Rojas Bracho
Instituto Nacional de Ecología (NIE), México
Dr Mercedes Pascual
Department of Ecology and Evolutionary Biology, University of Michigan (Ann Arbor), United States
Dr Marilyn Aparicio Effen
National Climate Change Program, Ministry of Planning, Bolivia
Dr Carlos Corvalan
Senior Advisor, Pan American Health Organization (PAHO)
Dr Jonathan Patz of the University of Wisconsin introduced the first plenary session on climate change and health. He noted “Global environmental change is not just about climate change.” He reminded the audience that the Forum’s opening speech addressed climate change, and confirmed that many of the Forum sessions would further develop this theme in relation to broader issues affecting sustainable development. He urged those with ecology and conservation biology expertise to submit their work to the EcoHealth journal, then introduced Dr Leonora Rojas Bracho of the National Institute of Ecology (NIE) of Mexico.
Dr Rojas Bracho presented her joint work with Adrián Fernández, NIE director. The NIE, now 10 years old, emphasizes scientific research for policy making. It is responsible for developing and updating the Mexican government’s climate change policy.
Dr Rojas Bracho said Mexico is among the countries most vulnerable to climate change. Desertification in the north, floods on the Gulf and the Yucatán coasts, forest degradation, loss of biodiversity, and impacts on human health are likely to occur. Mexico’s climate change projections foresee a 2°–4°C mean temperature increase by 2080, particularly in the north. The centre of the country, Mexico’s agricultural heartland, may see precipitation decreasing by 15% in winter and 5% in summer, affecting water availability. Rising sea surface temperatures will produce more hurricanes, and forest fires will worsen. Dr Rojas Bracho said she expects that by 2050, between 53%–62% of Mexican vegetation cover will be “exposed to new climatic conditions that differ from today’s current conditions.”
Dr Rojas Bracho said climate change would have direct and indirect effects on health. For example, heat waves will increase mortality. Chemical reactions involving environmental pollutants will be enhanced and will produce secondary pollutants and contaminants. Health effects may include heat strokes, especially for the elderly and children; changes in the ecology of vector-borne diseases like malaria and dengue are likely; as are increases or changes in food and water-borne diseases, food supply problems and respiratory diseases.
Dr Rojas Bracho correlated a 1°C temperature increase to a 1.2% rise in heat stroke mortality in the States of Sonora and Baja California.
Megacities in developing countries expose millions of citizens to high levels of air pollutants. In Mexico, well over 25 million inhabitants reside in cities where the air quality does not meet national air quality standards. The cities of Monterrey and Toluca now rival Mexico City for poor air quality.
Transportation provides an “important contribution to emissions,” representing 18% of Mexico’s annual carbon dioxide production. NIE studies on mitigating CO2 production focused on developing sustainable transportation options. Three studies were recently carried out in Mexico City (2002–03, 2004–05, and 2006–08). The latest involved a nationwide project on emission control, more efficient fuel use and improved vehicle technology. Cost-benefit analysis examined greenhouse gas controls and costs were defined as air quality, health impacts, and finances.
The 2002–03 study examined five emission control methods and showed strong net benefits from renovating taxis. The 2004–05 study examined Mexico City’s new Bus Rapid Transit corridor. With 250,000 passengers per day, benefits of using the corridor include significant decreases in both the annual production of nitrous oxide and lost work days as a result of illness. Responding to government and fuel industry inquiries, the NIE determined that the benefits of switching to sulfur-reduced fuels could represent twice the cost of implementation. Dr Rojas Bracho noted however that improved fuels and poor vehicle technology do not solve emission problems, and the NIE is now studying higher fuel efficiency in new vehicles.
Dr Mercedes Pascual of the University of Michigan talked about current trends in infectious diseases worldwide, and noted how these must be considered in terms of climatic, evolutionary, and socio-economic change.
She referred to the size and frequency of malaria epidemics, which have changed dramatically over the past decade in highland regions like in Kenya. Theories for these changes include drug resistance, increased exposure of non-immune populations, HIV/AIDS, land use changes, and climate change—the latter being “particularly controversial,” Dr Pascual said.
She listed five points of contention relating to climate change:
- Is there evidence of significant trends in climate data?
- Do such trends result in a significant change in the disease itself?
- Do risk maps of suitability indices change over time?
- Is drug resistance a more important factor than climate change?
- Is climate variability — inter-annual rainfall variation — a major driver of disease dynamics?
Dr Pascual reviewed a study in Kericho (Kenya), Kabale (Uganda), Gikongoro (Rwanda), and Muhanga (Burundi) indicating trends of increasing temperatures between 1950 and 2000. Temperature rise appears to affect mosquito populations, which in turn may correspond to increased malaria cases.
Another study projected malaria infection rates from 1980 to the present by examining temperature change impacts on larvae life cycles in relation to human infection cycles. The study indicated increasing epidemics, but the median projected infection rate relative to temperature was smaller than actual historical observations.
Temperature change could therefore explain a “significant fraction” of malaria increases in African highlands, but other factors exist, according to Dr Pascual. Citing climate change alone would be “unreasonable.” She said drug resistance is often cited as an alternative theory to climate change, but interaction between the two might also be possible.
“If climate change is changing the transmission intensity, then this would also change the rate of evolution in malaria,” she said.
Regarding suitability indices, Dr Pascual noted how dynamic research approaches focus on one location over time, but many climate change studies take a larger-scale, spatial approach to a habitat’s suitability for transmission. She said the two must be integrated to use suitability indices in temporal ways.
She cited Hay et al. (Nature 2002), who argued using Garnham’s suitability index that suitable malaria transmission conditions—temperatures over 15°C and two consecutive months of rainfall over 152 mm—have remained unchanged over the twentieth century. Dr Pascual’s work in Madagascar, plotting 1971–1993 data did not match Garnham’s index. It also showed three epidemics in the 1980s when Garnham’s transmission suitability index was “extremely low.” She said that dynamic data gathered in localized places like the highlands might undermine suitability indices.
Despite much theoretical debates in the literature on drug resistance, scientists know little about how drugs interact with climate change, especially as climate modifies transmission intensity. Dr Pascual cited Klein, Smith, Boni, and Laxminarayan (Malaria Journal 2008), who show how higher rates of drug resistance exist at lower malaria transmission levels. However, Talisuna et al. (American Journal of Tropical Medicine and Hygiene 2007) suggested higher drug resistance at both low and high transmission levels but lower resistance at medium transmission levels.
Dr Pascual believes that science does not yet understand the complex interaction between drug resistance and transmission, let alone in the context of climate change effects. She pointed to evidence showing significant trends in climate change that are affecting disease occurrence and spread. Maps of suitability indices do not sufficiently address temporal changes, and drug resistance is not independent of changes in transmission.
Dr Marilyn Aparicio Effen of the Bolivian Ministry of Planning said “climate change is a real problem affecting real people.” Bolivia features 33 types of ecosystems between 550 and 7,000 meters above sea level. Within these ecosystems, many factors interact in the health-disease process: immunity, biodiversity, education, food availability, human settlement, ecological changes, technology and industry, culture, agricultural development, migration, incomes, ancestral practices, trade, demographic change, and climate change. These jointly determine the quality of life, and affect a population’s productivity and healthy development.
Using a graph depicting climate change in Bolivia, Dr Aparicio Effen said that changes in maximum extreme temperature are the most serious for human health. Warmer winters and summers in La Paz in 1997–2007 compared to 1960–1990 suggest future hotter and drier climates.
Eighty percent of Bolivia’s glaciers are shrinking, endangering water supply. Climate change also exposes crops to disease, pests, and extreme weather conditions that affect crop growth and may lead to crop failure. Indirect health impacts also include malnutrition.
Dr Effen presented a map projecting significant changes in Bolivian ecosystem configurations by 2050, including forest degradation and recurrent droughts. Other maps dated from 1996 and 2003 showed how a southern province went from experiencing infrequent to frequent outbreaks of malaria.
Microhabitats for infectious parasites are witnessing “fairly important impacts,” particularly in Bolivia’s mountains. “Climate change produces ecosystem change,” said Dr Effen. “This results in geographic and altitudinal changes for malaria, and consequently in new health risks as well.”
Climate variability and extreme weather linked to El Niño and La Niña have increased in frequency and intensity since 1998. Recent floods—the worst in 60 years—damaged millions of hectares with $400 million losses, equivalent to 4% of Bolivia’s GDP. Flash floods in La Paz in 2002 killed approximately 80 people, while dengue in Santa Cruz has worsened since 1998.
Bolivia’s high vulnerability to climate change impacts influences its National Development Plan (NDP). As Bolivia produces 0.26% of global greenhouse gases, policy is focusing primarily on adaptation. The National Climate Change Adaptation Mechanism lists five priority sectors: water resources; food security; human settlement and risk management; health; and ecosystems.
The integrated approach to risk management combines scientific and anthropological research with education and public awareness programs.
Dr Aparicio Effen said ecohealth practitioners must similarly integrate their approach to mitigating climate change through science, methods, policies, processes, and citizen participation. “Assessing vulnerabilities and initiating adaptation simultaneously will foster better policy development,” she said.
The NDP, aiming to build resilience to climate change health impacts, features six interdisciplinary and intersectoral adaptation measurements:
- Inclusion of climate change in health programs and policies
- Identification of current and future scenarios for health vulnerability
- Proactive behaviour in the National Health System
- Disease prevention and protection of health
- Public education and participation
- A bioclimatic surveillance system to warn of impending disease events
The approach comprises both top-down sector development and bottom-up pilot adaptation projects.
Bolivia’s lessons about climate change adaptation include the value of local participation, the importance of learning-by-doing and of research, of evolutionary and dynamic conceptual frameworks for health care, and of mixed top-down/bottom-up approaches. The climate change adaptation learning process (action-experience-reflection-action) in the pilot projects takes 18 to 24 months, Dr Aparicio Effen said.
She concluded that developing countries with complex socio-economic conditions face bigger risks than others. Risk reduction must be comprehensive and multisectoral, with a coordinated, proactive, “multinational attitude” to ecohealth.
In his role as discussant for the session, Dr Carlos Corvalan of the Pan American Health Organization said the word “inequality ”—regarding water, food, and energy access—contextualizes climate change, as poor countries are far more vulnerable than rich ones. Priority is also an issue.
“Billions of dollars are floating around to save economies, so why are there none to save lives?” Dr Corvalan asked. However, he feels that there is room for optimism following the presentations of Drs Bracho, Pascual, and Effen. Challenges can and must be overcome, he said. “Ecohealth must not remain isolated.” Its research should focus not only on identifying problems but also on developing solutions.Read more about the IEF2008