Global warming, health warning

Greater incidence of disease

Global temperatures are already rising so fast that some species of plant and animal life have no time to adapt. They face extinction or, at best, much reduced habitat able to support fewer numbers. For other life forms, rising temperature increases their habitat and this is the case for mosquitoes and ticks, both of which carry diseases and infect humans with them.

These vectors are currently limited to habitat in hotter, more humid parts of Australia mostly in and north of Townsville on the east coast. They are rare or do not occur further south where winter temperatures fall to levels which kill them. However, as ambient temperatures increase, mosquitoes and ticks will move further south and survive winter in places such as Brisbane and the more densely populated southeast corner.

In a few decades from now disease carrying ticks and that harbinger of so many ills, the Anopheles mosquito, may even spread as far south as Sydney and bring with them serious diseases at present rare or unheard of in those places.

As mosquitoes and ticks spread further south, they will bring diseases for which, at present, there is limited treatment. Many of these diseases either kill or permanently and adversely affect humans, particularly those with impaired resistance to them.

Encephalitis, dengue fever and some forms of malaria and tuberculosis are particularly difficult to cure and can prove fatal. Others, such as asthma are rarely fatal if well managed but are exacerbated, becoming much more serious due to the presence of micro particles in the air caused by bushfires and dust-storms or worse, by an increase of atmospheric ozone.

While diseases causing diarrhea can be successfully treated, they weaken and disable those who contract them, usually from inadequately treated water but also from food. For example, rising sea surface temperatures can increase the presence of vibrio cholerae found in fish and increase the likelihood of contamination in imported food. Children are more susceptible to cholera than adults and more likely to die without timely treatment.

The World Health Organisation estimates that global warming is already responsible for 150,000 deaths annually and that half of these occur in the Asia-Pacific region. Mortality will increase as temperatures rise and vectors spread to more populated areas.

Increased ozone

Ozone is a molecular form of oxygen occurring at very low levels in the lower atmosphere. It is produced from oxides of nitrogen (NO and NO2) and other volatile substances emitted into the air by vehicles, fuel stations and power stations every day of the week. At present temperatures and in the presence of sunlight some of these are transformed into ozone, though seldom in such quantity that the ozone produced exceeds 40 parts per billion (ppb) for more than a few hours.

As global warming raises ambient temperatures, more of these substances are converted into ozone and its concentration in the lower atmosphere or troposphere rises. This is one of the major reasons why we need to avoid an increase of more than 2C in global temperatures. However, unless there is agreement at the Copenhagen Conference on significant reduction of greenhouse gas emissions the amount of ozone produced from these substances will increase to dangerous levels.

We can not live without oxygen (O2) but we can not live with ozone (O3). The presence of ozone in the troposphere in concentrations above 40 parts per billion near the earths’ surface is corrosive and toxic to humans, other air breathing animals and many food plants.

Ozone attacks the cells of the airway and lungs causing them to swell, produce fluid and fail in their ability to provide us with sufficient oxygen or protect us from diseases such as asthma caused by allergy and emphysema caused by smoking cigarettes.

If global temperatures rise more than 2C, ozone concentration in the lower atmosphere is likely to rise above 100 ppb, a level dangerous to health. The effects on humans of ozone at various concentrations for short periods of up to eight hours exposure are known and these are listed below: