Global change processes are likely to have wide-ranging and potentially serious health consequences. Some health impacts will result from direct-acting effects (e.g. heatwave-related deaths, and ultraviolet-induced skin cancer); others will result from disturbances to complex physical and ecological processes (e.g. changes in patterns of infectious disease, drinking-water supplies and agricultural yields). Effects on the health of human populations are likely to become evident within the coming decades. Furthermore, failure to reduce fossil fuel combustion (as the principal means of reducing greenhouse gas emissions) will result directly in a continuing (and increasing) avoidable burden of death and disease from exposure to local air pollution.
Human-induced changes in the global climate system and in stratospheric ozone pose a range of health risks that are likely to have potentially serious health consequences. These include: (1) increasing ultraviolet irradiation and an increased risk of skin cancer; (2) an increase in the number and severity of heat waves, causing heat exhaustion and deaths; (3) an increase in waterborne diseases, including cholera and cryptosporidiosis (acute diarrhoeal diseases are already a major cause of infant death and childhood illness in some European countries); (4) an increase in foodborne diseases caused by such bacteria as Salmonella and Campylobacter; (5) an increase in vector-borne diseases caused by climate-related changes in the ecology of vectors and parasites: for example, malaria is currently well controlled in western Europe but is already occurring sporadically in Turkey and the southern part of the former USSR, as milder winters increase the potential for transmission; (6) leishmaniasis, which is already occurring in southern France, Italy, Spain and Portugal; (7) tick-borne encephalitis - already found in southern Scandinavia and in countries in the eastern part of the European Region; (8) dengue fever: a disease not present in Europe, but the mosquito vector Aedes albopictus, which is already adapted to temperate climate, is already present in the Balkans and Italy; (9) death or injury caused by floods, storms and other violent weather events; and (10) climatic conditions may exacerbate the effects of air pollution and increase the burden of ill health.
The WHO reports (1999) "quantum leaps" in the incidence of malaria around the world coincident with extreme weather events associated with El Nino. Both heat and variations in rainfall affect transmission of the disease by mosquitoes. Kenya and Somalia; tens of thousands of people were affected by Rift valley fever and at least 200 died after the heaviest rains since 1961 attributed to El Nino fell on the region. Cholera has increased markedly over the last year in Latin America and Africa, where an epidemic has been in progress for seven years. The rise in cases is attributed to heavy rainfall and floods associated with El Nino.
Climatic changes related to global warming could unleash outbreaks of diseases like malaria, dengue fever, cholera and heat stroke. Predictions based on the belief that 1997 and 1998 are a taste of the future.
There is a lack of hard evidence and what there is, is circumstantial.