Climate Change and Human Health - Report


UNEP Press Release
(Jointly issued by UNEP, WHO and WMO)


GENEVA/NAIROBI, 12 July 1996 - Climate change is likely to disturb various natural and ecological systems thus triggering off a whole host of - mostly - adverse effects on human health. This is the main conclusion of CLIMATE CHANGE AND HUMAN HEALTH - a joint publication of the World Health Organization (WHO), the World Meteorological Organization (WMO) and the United Nations Environment Programme (UNEP), released today in Geneva at the current session of the Conference of the Parties of the United Nations Framework Convention on Climate Change.

Most of our current environmental health problems are of localized nature. However, many of the anticipated health effects of climate change would affect large populations in many regions.

The most direct health effects would be those caused by heatwaves, storms, and floods; the least direct would be those due to socioeconomic disruption caused by environmental deterioration. Many of the indirect public health effects would occur slowly, via climatic impacts upon agriculture, ocean fisheries, and infectious disease transmission.

Climatic factors also effect the emergence and resurgence of infectious diseases. Infectious diseases include vector-borne diseases, many of which are a major source of illness and death in developing countries. An estimated one in 20 people in the world are currently infected with malaria, with approximately 350 million new cases occurring annually. About 100 million people are at risk of contracting American trypanosomiasis (Chagas disease). Its geographical distribution ranges from the southern United States to southern Argentina and Chile. Onchocerciasis, or river blindness, is currently affecting 17.5 million people in Latin America and West Africa.

The distribution and abundance of vectors and intermediate hosts of these diseases are determined by various physical factors (temperature, rainfall, humidity, surface water availability, and wind) and biotic factors (vegetation, host species, predators, competitors, parasites and human interventions). An increase in ambient temperature is anticipated to cause net increases in the geographic distribution of vector organisms such as malaria mosquitoes, although some localized decreases may also occur. At the same time, temperature-related changes in the life-cycle dynamics of vectors and pathogens would increase the potential rate of transmission of vector-borne diseases in many parts of the world. Incidence of trematode infections, including schistosomiasis, may also rise due to climate- related changes in transmission dynamics and effects on the abundance of snail intermediate hosts.

It is estimated that the proportion of the world population exposed to the potential transmission of malaria could increase in a hundred years time from the current 45% to around 60%. Much of this increase would affect populations currently at the margins of malaria endemic areas in tropical, subtropical, and some less well-protected temperate zones. Increases in incidence of other infectious diseases such as cholera, and other water-related and food-related infections, could also occur, particularly in tropical and subtropical regions, following climatic impacts on water distribution, temperature and the proliferation of micro- organisms.

Climate change would lead to increased incidence of familiar, existing public health problems. An increase in the frequency of severity of heatwaves would translate into greater heat-related mortality and illness. Studies in North America, North Africa and China indicate that in very large cities, this would represent several thousand additional deaths annually. This trend is not expected to be counterbalanced by a possible slight decrease in cold-related mortality. Climate change is also likely to bring about major regional shifts in rainfall patterns and, with them, increased frequency or severity of droughts, floods, and bushfires. Drinking water supplies may also be affected. Injuries, deaths, and psychological and social disturbances attributable to these causes are likely to increase in affected regions.

The production of some types of air pollutants and, accordingly, incidence of their associated health impacts, such as cardio- respiratory disorders, would probably be exacerbated by climate change. A warmer and wetter climate in some regions could also result in higher airborne concentrations of various pollens and spores with a possible impact on allergic disorders, such as hay fever and asthma.

Climate change, via effects on soil, photosynthesis, pests and diseases, would affect agricultural productivity. Almost certainly, important regional differences would occur, with negative effects seen principally in lower-latitude lower-income countries. In those regions, malnutrition, hunger and other health problems could increase, particularly in children.

Sustained depletion of stratospheric ozone (technically speaking, not a component of climate change, but closely related to it), resulting in increased ground-level exposure to ultraviolet radiation, would cause an increase in the incidence of skin cancer. It may also increase the incidence of ocular lesions (for example certain cataracts), as well as suppression of the immune system. Increased ultraviolet radiation would also impair, to some extent, the photosynthetic productivity of land plants and marine phytoplankton -both of which are basic sources of human food.

Other indirect effects on health would result from the social-demographic disruptions caused by rising sea-level and from those caused by climate-related regional shortages in fresh water, food and other natural resources.

"The inherent "newness" of this topic - climate change as a hazard to human health - means that there is an urgent need for an expanded international effort", says Dr. Hiroshi Nakajima, WHO Director-General. "Health sciences must develop new and better methods for clarifying the relationship between public health and natural and human- induced climate change. Attaining a greater awareness of potential health impacts will require activities to educate the public health community and to encourage media coverage of this subject".

"We have gone beyond the point where the casual use of the atmosphere as a highly mobile dump for man's waste is possible", comments Professor G.O.P. Obasi, Secretary General of the WMO. "Any change in climate would have far-reaching environmental, biological, socio-economic and public health consequences".

"Climate change poses direct risks for both human health and ecosystems", says Ms. Elizabeth Dowdeswell, UNEP Executive Director. "Much of the damage to ecosystems could have additional consequences for human well-being, such as reduced water supplies in certain regions and increased storm damage".

The Intergovernmental Panel on Climate Change concluded in a recent report that "... the balance of evidence suggests that there is a discernible human influence on global climate".

For more information:

Mr. Robert Bisset                                       
Information Officer, UNEP Nairobi                              
Tel: 254-2-62-3084, Fax: 254-2-62-3692                                 

Mr. Valery Abramov
Health Communications and Public Relations,
WHO Geneva 
Tel: 41-22-791-2543, Fax: 41-22-791-4868

UNEP News Release 1996/43

Robert G. Bisset
Media/Information Officer
Information and Public Affairs
United Nations Environment Programme
PO Box 30552, Nairobi, Kenya 
Tel: +254-2-623084
Fax: +254-2-623692

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