Global warming, health warning

Although the following comments relate to Australia, they have broad application to most other countries.

Let there be no doubt, global warming is a killer. It is likely to contribute to or be the direct cause of your premature death because of the way in which it causes:

• loss of human habitat;
• greater incidence of disease; and
• increased ozone production.

Loss of human habitat

Humans can only live in a habitat where very limited climate conditions prevail, where for most of the time it is not too cold (above 0C) and not too hot (below 40C). Habitat that is wet enough to cultivate food, and dry enough to avoid prolonged high humidity. Outside these conditions, we struggle to survive and do not live for very long. Loss of habitat due to the effects of global warming poses serious threats to our survival.

Humans, and no less importantly the animal and plant species they depend on for food, can only cope with anything outside these parameters for a relatively short period. The effects of global warming and the increasing speed with which it is happening are therefore of immediate and longer term importance to humans.

Global warming produces climate extremes resulting in longer, more frequent periods of severe heat, draught, high winds, tidal surges and flooding. Such conditions pose a threat to our health and wellbeing, as evidenced by the 2009 extreme heat conditions in southeast Australia when temperatures exceeded 40C and remained above that level for almost a week. The resulting bush fires killed 173 people and destroyed thousands of houses and other property.

Less well known is that the heat during this short period caused the premature death of an estimated 200 people in southeast Australia. The very young and the old are particularly vulnerable to atmospheric temperatures in excess of normal body temperature. Had heatwave conditions lasted longer, the death toll would have been much higher.

Heatwave conditions result in a greater incidence of bushfires, accompanied by very dry conditions and high winds. These contribute to a contraction of the human habitat since they prevent reliable food production and water supply needed to sustain a population of any size, particularly very large urban populations. The latter then become dependent on food imported from more distant areas where it can be produced and on water saved and stored from recycling, infrequent rainfall and desalination.

Examples of this are already evident in areas of dense population such as Perth, Melbourne and the Brisbane - Gold Coast region. All are areas trying to cope with populations growing at such a rate that increased demand is placed on dwindling water and food supplies. The Goulburn Valley and other irrigation areas of Victoria, once aptly known as the food-basket of Australia, are faced with drying river basins unable to provide the water needed to sustain food production.

Global warming is already causing land based snow and ice to melt much faster than it is being formed with the result that, apart from the remnants of the Greenland and Antarctic Ice caps, the planet is likely to be ice free by 2100. The consequences of this have been described elsewhere.

Suffice it to say that this will result in sea level rises inundating low lying coastal lands where 70 per cent of the population live - and result in loss of land currently used for production of the food on which they depend. It will only be possible to maintain food security by reducing exports or by importing more.

If population growth is not curtailed, the presently low incidence of malnutrition will increase significantly. This will reduce resistance to diseases, particularly vector borne diseases, which either do not occur or are rare at present.