How climate variability affects health

Dr Margaret Chan
Director-General of the World Health Organization

Address to the Extraordinary Session of the World Meteorological Congress
Geneva, Switzerland

29 October 2012

Secretary-General, Michel Jarraud, distinguished delegates, ladies and gentlemen,

Prevention and preparedness are the heart of public health. Risk management is our daily bread and butter. Information on climate variability and climate change is a powerful scientific tool that assists in these tasks. Up to now, this tool has been underutilized.

The Global Framework for Climate Services, and the implementation plan you will be discussing during this session, promise to change this situation in exciting ways.

The plan focuses on four areas for the application of climate information with the greatest potential for an immediate impact on human lives. Health is one. The remaining three are fundamental determinants of health. Namely: agriculture and food security, disaster risk management, and water.

Climate and weather affect the air people breathe, the food they eat, and the water they drink.

Climate variables contribute to natural disasters, with their related population displacements, lost livelihoods, destroyed infrastructures, and conditions of crowding and filth that favour explosive outbreaks of disease. Diarrhoeal diseases, the second biggest killer of young children worldwide, flourish under such conditions.

Many of the world’s most worrisome diseases have transmission cycles that are profoundly shaped by conditions of heat and humidity and patterns of rainfall.

I am talking about malaria, its parasites, and the mosquitoes responsible for transmission. All are highly sensitive to climate variability, which has been repeatedly linked to epidemics.

Scientists use climate data sets, based on advances in seasonal forecasting, to predict unusual increases in malaria transmission and facilitate preparedness. Doing so is critically important, as a child infected with malaria can die within 24 hours in the absence of medicines.

Malaria matters greatly. In endemic areas, and especially in Africa, this disease is the single biggest health-related barrier to economic development.

I am also talking about epidemic-prone diseases, like cholera, dengue, and bacterial meningitis. All are major diseases infecting large numbers of people, and all are highly sensitive to climate variability.

Cholera is a close companion of heavy rainfall and floods, but epidemics can also be ignited by drought conditions that compromise water safety and food hygiene.

Over the past five decades, the worldwide incidence of dengue has risen 30-fold. Today, dengue ranks as the most important mosquito-borne viral disease in the world. Everywhere, the human and economic costs are staggering. Studies show that high temperatures and humidity and low wind speed correlate with epidemics.

Bacterial meningitis is probably the most dreaded of all infectious diseases in sub-Saharan Africa. Nearly every year, deadly and debilitating epidemics sweep through Africa’s meningitis belt. What actually sparks these epidemics is not yet fully understood, but the link to climate is strong. Epidemics consistently arrive together with the hot, dusty Harmattan winds.

For all of these diseases, stronger climate services in endemic countries can help predict the onset, intensity, and duration of epidemics. Such predictions go to the heart of public health: that is, prevention and preparedness.

These epidemics have a huge potential for social disruption and make huge logistical demands on response teams. Knowing what may be on the horizon allows health officials to pre-position medicines, vaccines, and other interventions that help keep the death toll down.

Climate also influences the emergence of new diseases. Nearly 80% of all new human diseases originate in domestic or wild animals. Climate variables, including those that influence the availability of food and water, have a direct impact on wild animal populations, their concentrations, and their incursion into areas inhabited by humans.

Climate-related shifts in animal populations can allow an animal pathogen to jump the species barrier and infect humans, as in the case of Nipah virus in Malaysia, and Hanta virus in the US. In this case, emergence of a severe new respiratory disease was linked to a long period of drought, followed by heavy rainfall, that affected populations of deer mice.

As another example, migratory birds can spread diseases like West Nile fever and the deadly H5N1 avian influenza across continents and oceans. Migration is triggered by environmental conditions, including winds and events like cold fronts. When these diseases have an intermediate host, like pigs for Nipah virus and poultry for avian influenza, the economic costs can be enormous.

For all these diseases, what WHO Member States want is to move from a reactive response to an emergency situation to proactive risk assessment, early warning systems, and preventive measures. Climate services offer a powerful resource for doing so.

Ladies and gentlemen,

The World Climate Conference– 3, organized by WMO in 2009, drew attention to the growing relevance of climate information to all countries in virtually every sector of society. That congress also concluded that the most urgent need is for much closer partnerships between the providers and users of climate services.

Last week’s dialogue on climate services reinforced these messages, with instructive examples of health and meteorological services working together, from the global to the national level.

These meetings support an important conclusion. The greatest contribution of climate services to health comes when the end-users are partners in the definition, management, and implementation of these services.

I have given you just a small inventory of areas where health planning and actions can benefit from meteorological and hydrological services. There are many others.

Climate has a profound impact on the lives, and survival, of people. Climate services can have a profound impact on improving these lives, also through better health outcomes.

As the world’s climate continues to change, the links between climate and health will become increasingly apparent and increasingly seen as priorities for urgent action.

WHO welcomes the Global Framework for Climate Services. I am glad that the draft implementation plan explicitly mentions WHO as a potential partner and prime user of climate information.

Like WHO, the Framework gives priority to the needs of vulnerable groups and to the building of capacity in the developing world. We welcome this emphasis. As just one example, the use of climate data to forecast malaria transmission is limited by the lack of high-quality data from weather stations in large parts of Africa, where the malaria burden is overwhelmingly concentrated.

WHO enjoys a long history of fruitful collaboration with WMO. We look forward to building on this foundation as you implement the Global Framework.

Thank you.