GENEVA -- Scientists tell us that the evidence the Earth is warming is "unequivocal." Increases in global average air and sea temperature, ice melting and rising global sea levels all help us understand and prepare for the coming challenges. In addition to these observed changes, climate-sensitive impacts on human health are occurring today. They are attacking the pillars of public health. And they are providing a glimpse of the challenges public health will have to confront on a large scale, WHO Director-General Dr Margaret Chan warned today on the occasion of World Health Day.

"The core concern is succinctly stated: climate change endangers human health," said Dr Chan. "The warming of the planet will be gradual, but the effects of extreme weather events -- more storms, floods, droughts and heat waves -- will be abrupt and acutely felt. Both trends can affect some of the most fundamental determinants of health: air, water, food, shelter and freedom from disease."

Human beings are already exposed to the effects of climate-sensitive diseases and these diseases today kill millions. They include malnutrition, which causes over 3.5 million deaths per year, diarrhoeal diseases, which kill over 1.8 million, and malaria, which kills almost 1 million.

Examples already provide us with images of the future:

• European heat wave, 2003: Estimates suggest that approximately 70 000 more people died in that summer than would have been expected.
• Rift Valley fever in Africa: Major outbreaks are usually associated with rains, which are expected to become more frequent as the climate changes.
• Hurricane Katrina, 2005: More than 1 800 people died and thousands more were displaced. Additionally, health facilities throughout the region were destroyed critically affecting health infrastructure.
• Malaria in the East African highlands: In the last 30 years, warmer temperatures have also created more favourable conditions for mosquito populations in the region and therefore for transmission of malaria.
• Epidemics of cholera in Bangladesh: They are closely linked to flooding and unsafe water.

These trends and events cannot be attributed solely to climate change but they are the types of challenges we expect to become more frequent and intense with climate changes. They will further strain health resources that, in many regions, are already under severe stress.

"Although climate change is a global phenomenon, its consequences will not be evenly distributed," said Dr Chan. "In short, climate change can affect problems that are already huge, largely concentrated in the developing world, and difficult to control."

To address the health effects of climate change, WHO is coordinating and supporting research and assessment on the most effective measures to protect health from climate change, particularly for vulnerable populations such as women and children in developing countries, and is advising Member States on the necessary adaptive changes to their health systems to protect their populations.

WHO and its partners -- including the UN Environment Programme, the Food and Agriculture Organization, and the UN World Meteorological Organization -- are devising a workplan and research agenda to get better estimates of the scale and nature of health vulnerability and to identify strategies and tools for health protection. WHO recognizes the urgent need to support countries in devising ways to cope. Better systems for surveillance and forecasting, and stronger basic health services, can offer health protection. WHO will be working closely with its Member States in coming years to develop effective means of adapting to a changing climate and reducing its effects on human health.

"Through its own actions and its support to Member States," said Dr Chan, "WHO is committed to do everything it can to ensure all is done to protect human health from climate change."