Dr Margaret Chan Director-General of the World Health Organization

This was the 2007 David E. Barmes Global Health Lecture, Bethesda, Maryland, USA

A look at reality of climate change

I will address the reality of climate change. I will base my remarks on conclusions set out in the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, issued last month.

I will consider what a vast body of evidence has to say about the health implications of specific climate-related changes projected in that report. I will interpret these implications in terms of the current drive to accelerate health development and, more specifically, our collective determination to meet the Millennium Development Goals.

Let me express my optimism at the start. The Millennium Declaration and its Goals represent the most ambitious commitment ever made by the international community. These Goals attack the root causes of poverty, and acknowledge that these causes interact in intricate ways. They bring renewed vigour to the multisectoral approach to health advocated by WHO as part of primary health care and the Health for All movement.

The Goals champion health as a key driver of socioeconomic progress. In so doing, they elevate the status of the health sector. Health is no longer a mere consumer of resources. It is also a producer of economic gains.

The achievement of these Goals, within the next seven years, would make the biggest difference in the lives and future prospects of impoverished populations in the history of humanity. If the international community meets these goals, we will have the upper hand on ancient impediments to human development long considered intractable: poverty, ignorance, disease, unhealthy environments, and premature death from preventable causes.

New initiatives and impressive results

In my first year in office, I have witnessed the depth of commitment to these goals on many different levels. Health has become a fruitful – and a friendly – arena for foreign policy. I have stood together with heads of state as they launched initiatives for diseases and conditions rarely seen within their borders. I want to take this opportunity to thank this country, and its President, for the initiatives that are addressing AIDS and malaria.

As you know, we are seeing some impressive results. When the 3 by 5 initiative was launched in December 2003 by my predecessor, Dr JW Lee, only around 100 000 people in developing countries were receiving antiretroviral therapy. By December of this year, that figure had risen to more than 2.5 million people.

Around a decade ago, observers of the malaria situation had one main observation. The malaria situation is stable, they said. It could hardly get any worse. Today, I believe we are seeing a wind of change that could turn this disease around, and possibly very quickly.

These are solid reasons for optimism. But there are more. We have some big new sources of support, some true innovations. We have the Global Fund to Fight AIDS, Tuberculosis and Malaria. We have the GAVI Alliance, which is helping us reach record levels of coverage with childhood immunization. We all know the importance of humanitarian funds, such as those provided by the Bill and Melinda Gates Foundation. We know, too, how Gates support has raised our level of expectations for malaria control.

Innovative way to finance immunization

As I have seen, commitment to humanitarian goals can unleash the very best of human ingenuity. Last year brought us three examples. As part of the GAVI Alliance, we saw the launch of the International Finance Facility for Immunization. Borrowing an approach used in financial markets, this facility is frontloading US$ 4 billion to fund the immunization, by 2015, of 500 million children.

In another innovation, Advance Market Commitments are being used as an incentive to encourage industry to develop new vaccines for diseases of the poor. By securing legally-binding financial pledges in advance, this mechanism tells industry that, when a new product is brought to market, the money to purchase the product will be there. In short, it is circumventing a hard reality. Market forces drive R&D, and these forces will not foster product development for markets that cannot pay.

Last year also saw the launch of UNITAID, a drug purchasing facility which draws funds from a tax on airline tickets. This is truly a sustainable source of new funds on a substantial scale. It represents a deliberate effort to channel some of the wealth of globalization towards health needs in the developing world. The first supplies of quality-assured drugs for HIV/AIDS and malaria have already been delivered.

This then gives some indication of the level of international commitment and determination. There will always be unmet needs, but health has never before received such attention or enjoyed such wealth.

Weak health systems

Not all the news is good. With so much working in our favour, we can see what is holding us back. We have commitment, money, powerful interventions, and proven strategies for implementation. Here is the problem. The power of these interventions is not matched by the power of health systems to deliver them to those in greatest need on an adequate scale and in time.

We have other big problems. All around the world, health is being shaped by the same powerful forces of globalization. Urbanization is a global trend, with rates growing fastest in the developing world. Demographic and epidemiological transitions are global trends, now joined by behavioural and nutritional transitions.

Industrialization of food production, globalization of the food supply and its distribution and marketing channels mean that all of us are increasingly eating similar unhealthy diets. With the massive move to cities, lifestyles are increasingly sedentary. Obesity has gone global.

Chronic diseases, long considered the companions of affluent societies, have changed places. They now impose their heaviest burden on low- and middle-income countries. Here is one example. In Cambodia, a least developed country, one in 10 adults now has diabetes and one in four adults has hypertension.

The rise of chronic diseases and the demands of chronic care are placing an almost unbearable strain on health systems. The costs for impoverished households can be catastrophic. In parts of rural China, for example, 30–50% of poor farmers cite ill health or the costs of chronic care as the root cause of their poverty.

Health care must reach the poor

Two conclusions are obvious. If we want better health to work as a poverty reduction strategy, we must reach the poor. If we want health to reduce poverty, we cannot let the costs of health care drive impoverished households even deeper into poverty.

Public health has been given a big push forward, but it is still an uphill climb. Here is the reality. Interventions and money will have only a limited impact in the absence of adequate delivery systems.

If I had to select a single development over the past year that encouraged me most, it would be this. International agencies working in health, the major funding agencies, foundations and donors now fully understand the absolute necessity of investing in basic health systems and infrastructures. This is a major step forward.

Ladies and gentlemen,

With this as a background, let us look at climate change.

At the start of this century, a group of British journalists ran a competition for the best fictitious story that might depict what lies ahead during this century. Here is one of the winners: “Heads of state, meeting today on the tropical island of Switzerland, have reached consensus. Predictions of global warming have no foundation in science.”

My, how things have changed. The power of scientific research has triumphed. The verdict is in. Climate change is real. Human activities are a prime cause. The consequences are already being felt in ways that can be measured. Humanity will suffer, for some decades to come, for past sins in the way we have inhabited this planet.

As the climate scientists tell us, even if greenhouse gas emissions were to stop today, the consequences will be felt throughout this century. In the language of the scientists, human activities have committed this planet to climate change. The emphasis now is on the ability of our human species to adapt to changes that have become inevitable.

The warming of the planet will be gradual, but the increasing frequency and severity of extreme weather events – intense storms, heat waves, droughts, and floods – will be abrupt and the consequences will be acutely felt.

Place health at the centre of climate agenda

The health sector must add its voice – loud and clear – to the growing concern. Just as we fought so long to secure a high profile for health on the development agenda, we must now fight to place health issues at the centre of the climate agenda. We have compelling reasons for doing so. Climate change will affect, in profoundly adverse ways, some of the most fundamental determinants of health: food, air, water.

This is the reality that concerns me the most. Developing countries will be the first and hardest hit. Subsistence agriculture will suffer the most. Areas with weak health infrastructures will be the least able to cope.

Imagine the impact on health in areas where the food supply is already precarious, rural areas are populated with subsistence farmers and the capacity to cope with any emergency is already fragile.

Imagine the situation in cities, when water scarcity combines with heat stress and air pollution. We already have good evidence linking such conditions to increased deaths from respiratory and cardiovascular disease, especially in the elderly.

As the scientists tell us, the nature of climate change during this century is likely to go beyond human experience. But public health has abundant experience as a basis for interpreting the health consequences and understanding their impact. Public health has decades of experience in dealing with problems that will be made bigger and broader by climate change.

Ladies and gentlemen,

When I announced to my staff that I had selected climate change as the theme for next year’s World Health Day, I described climate change as the defining issue for public health during this century.

Let me take this statement one step further today. I have given my impressions about the public health landscape of today, the difficult challenges we face, but also the many reasons for unprecedented optimism.

Impact of climate change

I believe that climate change will ride across this landscape as the fifth horseman. It will increase the power of the four horsemen that rule over war, famine, pestilence, and death – those ancient adversaries that have affected health and human progress since the beginning of recorded history. Research already has a great deal to say about the impact of climate change on famine and pestilence.

Let us consider famine, hunger, food security, and malnutrition. In many parts of the world, the severe adverse effects of climate change – one could say, the catastrophic effects – are not expected to be felt until around the middle of this century or even later.

Not so for Africa. According to the latest projections, Africa will be severely affected as early as 2020. This is just a dozen years away. By that date, increased water stress is expected to affect from 75 million to 250 million Africans. A dozen years from now, crop yields in some countries are expected to drop by 50%.

Imagine the impact on food security and malnutrition. In many African countries, agriculture remains the principal economic activity, and agricultural products are the principal source of export trade. Vast rural populations survive, hand-to-mouth, on subsistence farming. There is no surplus. There is no coping capacity. Yes, as I said, these are catastrophic effects.

Influence of weather on epidemics

Concerning pestilence, abundant evidence links the distribution and behaviour of infectious diseases to climate and weather. As the scientists say, climate defines the geographical distribution of infectious diseases. Weather influences the timing and severity of epidemics.

Diseases transmitted by mosquitoes are particularly sensitive to variations in climate. Warmth accelerates the biting rate of mosquitoes and speeds up maturation of the parasites they carry. Sub-Saharan Africa is already home to the most severe form of malaria and the most efficient mosquito species. What will happen if rising temperatures accelerate the lifecycle of the malaria parasite? What if malaria spreads to new areas?

NIH funded the landmark study that demonstrated a link between climate variability and increased malaria epidemics in the highlands of East Africa. We all know about the explosive epidemic potential of malaria when this disease reaches non-immune populations. Though we are making progress, we are still not able, right now, to achieve adequate population coverage with preventive interventions in areas of stable malaria transmission.

The landmark publication on microbial threats, issued in 1992 by the Institute of Medicine, opened the eyes of the world to the growing menace of emerging diseases. It also showed how changes in the way humanity inhabits this planet have created abundant opportunities for microbes to exploit.

Disruptions to ecological balance

It is easy to see how climate change will increase these opportunities in significant ways. When we consider the effects of climate change on emerging diseases, we are looking at disruptions to intricately balanced ecological systems that reached equilibrium following centuries of evolution. Nature gives us every reason to believe that disruption of this delicate equilibrium will have profound consequences.

Consider the emergence of hantavirus pulmonary syndrome in the south-west of this country in 1993. The appearance of that disease has been linked to a 10-fold increase in the mouse population, which followed an unusual weather event that killed off species that prey on mice. We see what can happen when weather disrupts an intricate ecosystem.

Let me give you another example of what might be in store. As noted in the November climate report, El-Nino driven bush fires and drought, as well as changes in land use and land cover, have caused extensive alterations in the habitat of bat species that are the natural reservoir of the Nipah virus.

From Malaysia to Bangladesh

Let us look at the health consequences. The disease emerged in 1999 in Malaysia among pig farmers. Close contact with pigs, the intermediate host, was quickly identified as the risk factor. Then came the first consequence.

The disease was initially misdiagnosed, by a WHO Collaborating Centre, as Japanese encephalitis. This misdiagnosis was caused by the co-infection of a patient with Japanese encephalitis and Nipah virus. The diagnosis led to a hugely expensive, disruptive and useless containment effort directed at mass vaccination and mosquito control.

Pigs and people continued to die. Confidence in the government plummeted. Malaysian scientists isolated the virus and identified Nipah as a new disease. That solved part of the problem.

Altogether 265 cases and 105 deaths occurred, with an overall case fatality rate of 39%. Investigation of the outbreak found no evidence of human-to-human transmission.

Case closed? Not at all. In 2001, the virus resurfaced in India and Bangladesh. In Bangladesh, outbreaks are now recurring annually according to a seasonal pattern. Evidence from these outbreaks indicates that the virus has become more pathogenic for humans.

The case-fatality rate has risen to almost 75%. Contact with pigs is no longer necessary. Human-to-human transmission, also after only casual contact, has been documented. In one case, a rickshaw driver died of the disease after transporting a patient to hospital. Furthermore, transmission within hospital settings is now strongly suspected.

In one outbreak, consumption of fresh date palm juice, contaminated by bat saliva or faeces, has been identified as the vehicle of transmission in several fatal human cases. So from a zoonosis, to human-to-human, to foodborne in a very short time. Fortunately, up to now, outbreaks have occurred in sparsely populated rural areas, thus limiting their size.

New diseases, new challenges

Let me make one personal comment on the issue of new diseases. Initial misdiagnosis is the norm when new diseases emerge. They are, by definition, poorly understood. The US initially misdiagnosed the first cases of West Nile fever as St Louis encephalitis. I was in charge of the health department in Hong Kong when SARS emerged.

My life long, I will never forget the agony of uncertainty as Hong Kong scientists worked day and night to determine what was killing our doctors and nurses, what microscopic beast had invaded our hospital system. Then as now and in the future, doctors and nurses are at the frontline when a new disease emerges. Then and in the future, they put their lives at risk.

Let us turn to the impact of climate on war and death. We know that competition for resources, and especially competition for scarce water, has been a so-called “war starter” on many occasions in the historical past.

Some argue that the consequences of climate change may provoke an increasing number of conflicts. I do not know. But I certainly know what conflict and complex emergencies mean for health.

WHO has had offices in Darfur for the past four years. Many attribute the origins of this conflict to severe drought, followed by population movements and fierce competition for resources.

I know another thing, too. Many of the unspeakable atrocities that affect civilians in this conflict occur when women and young girls leave the safety of refugee camps in their desperate search for firewood. In this scorched and barren land, it may take them two days to gather sufficient firewood. Two days at risk of sexual violence and mutilation. This is the utter desperation.

Impact of climate change on health inequity

Let us look at death, and let us do so from a public health perspective. Public health looks especially hard at preventable deaths. This is my greatest personal concern. Climate change could vastly increase the current huge imbalance in health outcomes. Climate change can worsen an already unacceptable situation that the Millennium Development Goals were explicitly and intricately designed to address.

Let me remind you. The Millennium Declaration and its Goals are all about fairness. As stated: “Those who suffer or who benefit least deserve help from those who benefit most.” More specifically, the Declaration stresses fairness in a world that is being radically reshaped by the forces of globalization.

As stated: “The central challenge we face today is to ensure that globalization becomes a positive force for all the world’s people. For while globalization offers great opportunities, at present its benefits are very unevenly shared, while its costs are unevenly distributed.”

This is indeed the problem. Globalization creates wealth and this is good. But globalization has no rules that guarantee fair distribution of this wealth. Health and wealth are intricately linked. The consequences of inequity can be measured by the great and growing gaps in health outcomes. I believe that, in matters of health, our world is dangerously out of balance, possibly as never before.

Fairness in access to health care really is a matter of life and death. The principle is easy to express. People should not be denied access to life-saving or health-promoting interventions for unfair reasons, including those with economic or social causes.

Wide gap in life expectancy in poor and rich countries

Let me give some examples. The difference in life expectancy in poor and rich countries now varies by more than 40 years. Medicine has never before possessed such a sophisticated arsenal of tools and technologies for curing disease and prolonging life. Yet each year, more than 10 million young children and pregnant women have their lives cut short, largely from causes that could have been prevented by available, affordable, and effective interventions.

As I said, this is my greatest concern. With impoverished populations in the developing world the first and hardest hit, climate change is very likely to increase the number of preventable deaths. The gaps in health outcomes we are trying so hard to address right now may grow even greater.

This is unacceptable.

Ladies and gentlemen,

Against this background of reasons for great optimism, followed by some truly hair-raising projections of what lies in store, let me conclude with a return to some optimistic thinking. The challenges ahead are enormous, but I am heartened by two facts. First, I have seen the kind of truly innovative solutions that arise when commitment and determination unleash the power of human ingenuity. Second, and perhaps most importantly, I believe that many of the things we are doing right now in public health are exactly what is needed to increase the resilience and adaptive capacity of developing countries.

Let me make some specific recommendations.

First, action to mitigate climate change, on a sufficient scale, will not take place until countries unite behind an agreed policy. We know this. We are seeing every day the headlines coming out of Bali. The health sector is not in a position to mitigate climate change in a direct and substantial way. But health is in a strong position to give the policy debate some compelling evidence-based arguments.

Human species in danger

Up to now, the polar bear has been the poster child for climate change. We need to use every politically correct and scientifically sound trick in the book to convince the world that humanity really is the most important species endangered by climate change.

Second, the inevitability of climate change gives us one more extremely compelling reason to meet the Millennium Development Goals. As clearly stated in the November report on climate change, poverty and ill health reduce the resilience and adaptive capacity of developing countries. Countries that have basic infrastructures in place, including essential health and emergency services, are in a better position to cope.

The report is even more explicit. As stated: “Critically important are factors that directly shape the health of populations, such as education, health care, public health initiatives, and infrastructure and development.” These factors are, of course, those largely addressed by the Millennium Development Goals.

Third, implementation of the strengthened International Health Regulations, which came into force this June, is another thing we are doing right now that has a dual purpose. It increases global health security, and it equips the world to cope with the expected emergence of new diseases and changes in the distribution or severity of epidemic-prone diseases.

Surveillance and response capacities needed

To meet their obligations under these regulations, countries need to have in place a set of core surveillance and response capacities. This fits with the new objective of pro-active risk management: stopping an event at source before it has a chance to become an international threat.

Furthermore, by collecting background data on what is normal for a given season or geographical area, the system increases the capacity to detect the abnormal. As preparedness for a warmer more erratic future, the surveillance and response system needs to develop more early warning systems, as has been done for famine alert. These systems can take advantage of powerful new technologies, like geographical information systems and earth-sensing satellites. Work on such early warning systems is already well advanced for diseases like malaria and Rift Valley fever. But we need to develop more.

Fourth, another thing we are doing right now, and doing very well, I might add, is alleviating poverty through a frontal attack on the neglected tropical diseases. These ancient debilitating diseases are strongly associated with poverty. They thrive in areas where water supply and sanitation are inadequate, vectors proliferate, housing is substandard, nutrition is poor and populations are illiterate. These diseases sap the productivity and curtail the human potential of at least one billion people who are the poorest of the poor.

Nearly all of these diseases are now supported by drug-donation partnerships with time-bound goals set for eradication or elimination. Last year, WHO introduced a strategy, involving the mass administration of preventive chemotherapy, that tackles several of the most burdensome of these diseases in an integrated manner.

Strong community motivation

The strategy is good, the momentum is strong, and progress is truly impressive. Moreover, as these diseases are so greatly dreaded by affected populations, strong community motivation is another plus. Just this past year, we have seen more and more evidence that mass preventive chemotherapy can actually break the chains of transmission for some of these diseases. For example, Egypt and China have eliminated lymphatic filariasis, an ancient scourge that currently affects an estimated 120 million people and has left 40 million permanently disabled.

If we manage to free endemic countries and their populations from the burden of these diseases, this, too, will increase adaptive capacity. If we fail, we must anticipate that deteriorating conditions associated with climate change may anchor even more people in abject poverty.

Fifth, health has not always been on the very best of terms with other sectors that will be affected by climate change. For example, we have abundant evidence of the impact new dams and irrigation systems can have on the prevalence of malaria and many other epidemic-prone diseases.

I strongly recommend that every development project include a health impact assessment as a mandatory component. This applies to the construction of dams, the design of irrigation projects, the design of a transport system and the siting of an industry or power plant.

Importance of international resilience

Sixth, we need to strengthen international capacity to respond to natural disasters. This is something I have been working on at WHO. We have been told, in no uncertain terms, to anticipate more frequent and more severe extreme weather events. Resilience is not just important at the national level. We need this resilience internationally as well.

Seventh, we must look after the welfare of women everywhere, but most especially in the developing world. The November climate report cites evidence that women are particularly vulnerable to the effects of natural diseases. But evidence also shows that women are usually the ones that pull communities back together after the event. Women are the ones who take charge of relief efforts and reconstruction and make them work. Investing in their welfare is an investment in future resilience.

Finally, we must never forget the strategic and persuasive power of evidence at the policy level. The very attention now being given to climate change is a true triumph for the power of scientific evidence.

We may need to use evidence to change some stubborn public opinions. We did this recently with DDT recommendations for malaria control, and I thank US scientists for lending their support. We may also need to do this to encourage the introduction of new crop species that produce better yields, need less water, can grow in brackish soil, or resist heat and new insect pests.

Studying interface of climate change and health

Concerning the importance of research, I have one last example. The Special Programme for Research and Training in Tropical Diseases has established a new group of experts to address interactions between the environment, agriculture, and infectious diseases. This group will explore the interface of climate change and health as part of its mandate.

With other partners, it will seek to identify critical research issues. It will be administratively based in China in collaboration with the Institute for Parasitic Diseases in Shanghai and the WHO country office in Beijing.

Ladies and gentlemen,

Progress in public health is rarely linear. Like history, public health moves in fits and starts. We have breakthroughs, and we have setbacks. Research develops a miracle drug. The microbe develops resistance.

With the support of health ministries and the GAVI Alliance, global coverage with childhood immunization reached record levels last year. And yet year after year, the number of new babies being born gets bigger, and the challenge expands.

We eradicated smallpox in 1979. A host of new diseases subsequently emerged. Of these, HIV/AIDS has been the most devastating and unforgiving of them all. It has been the ultimate setback for many hard-won gains.

This century, climate change – a fifth horseman, a new threat of a magnitude unknown to human experience – will ride across our promising landscape of public health. It will ride on a collision course with all the fits and starts of our progress, sometimes fragile, sometimes fundamental.

If the drive to reach the Millennium Development Goals does succeed in strengthening basic health systems, if implementation of the International Health Regulations improves our early warning and response capacity, if we can relieve poor people of crippling disease burdens, then together we can take a stand against this newest evil that has been cast our way.

We are obliged to do so, in a spirit of solidarity, motivated by the pursuit of fairness in our out-of-balance world, but above all for the sake of our common humanity.