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Climate change and its effect on water supply and usage
Climate change will have a profound effect on Council’s Water and Sewerage undertakings, that’s the view of Council staff who attended a three day course “Carbon Accounting in the Water Industry”.
- Does the hole in the ozone layer have anything to do with climate change?
- What is climate change?
- What does climate change mean for Australia?
- What does climate change mean for the water industry?
Although there are some weak linkages, the simple answer is “no”.
The earth’s atmosphere, and in particular ozone high up in the atmosphere, blocks up to 98% of ultra violet radiation from the sun. We know the 2% of ultraviolet rays reaching the earth can cause sunburn and skin cancer. Without the ozone layer, the effect on humans or animals could be much worse.
Ozone is a molecule of oxygen, consisting of three atoms (O3) instead of the more stable two atom molecule (O2).
Research in 1973 suggested that chlorofluorocarbons (CFC’s) could break down the protective ozone layers high up in the atmosphere. CFC’s are a group of chemicals developed in the 1920’s that were widely used as refrigeration gases and propellants in aerosol cans.
At this time, this theory was accepted by some, rejected by others. However, in 1985 British Antarctic Survey scientists shocked the scientific community with their physical measurements which indicated a large hole in the ozone layer had appeared over Antarctica.
This led to international concern and action. In 1987 the Montreal Protocol on substances that deplete the Ozone Layer was developed. Since then 191 nations have signed this international treaty which requires signatory nations to halt production of CFC’s and other ozone depleting substances.
Only (5) five nations have not signed the Protocol.
Since the Montreal Protocol came into effect, the atmosphere concentrations of the most important CFC’s and other ozone depleting gases have either levelled off or decreased.
The “hole in the ozone layer” could be said to have paved the way for climate change because:
- It focused widespread incident attention on the importance of the atmosphere to life on earth.
- It demonstrated just how quickly man’s activities could adversely affect the atmosphere.
- It established a precedent of international co-operation and action to address this issue, which went beyond the bounds of individual nations.
In the 1970’s scientists proposed a theory that changes in the concentration of gases that made up the atmosphere could cause a change in the amount of radiant energy from the sun being retained by the earth. The atmosphere consists of nitrogen (78%), oxygen (21%), carbon dioxide (.04%) and small amounts of other gases.
The atmosphere has naturally occurring gases which retain energy from the sun. These gases include carbon dioxide, water vapor, methane and ozone. It should be appreciated that without these so called “greenhouse gases” the earth would be so cold it would not be habitable.
In particular it was suggested that carbon dioxide would increase as a result of burning fossil fuels such as coal or oil.
At first there was debate in the scientific community about whether an increase in carbon dioxide in the atmosphere would increase or decrease temperature of the earth. With the natural variability of weather and climate patterns it was considered that it would be difficult, or at least take a long time, to establish any change in temperature from physical measurements.
However, advances in science, especially in measuring techniques and satellites, established sooner than anticipated that the average temperature of the surface of the earth was indeed rising.
The term “greenhouse effect” was coined. “Greenhouse gases” was the term used to describe gases that caused this effect. Chief among them was carbon dioxide (CO2), the greatest by volume.
A large proportion of heat from the sun is normally reflected straight back by the white polar regions. As the earth heats up they are expected to melt, thereby reducing even further radiation back into space and accelerating the warming process.
Due to similar processes, scientists have predicted that climate change will continue for more than a thousand years, even if greenhouse levels are stabilized at today’s levels.
The effects of climate change are expected to be: -
- Changes in weather patterns. Many areas are expected to become drier but a few areas may become wetter.
- Changes in the intensity of rainfall and storm events, largely as a result of the extra energy in the atmosphere.
- Rise in sea level
- Retreat of glaciers and ice areas
- Changes in agricultural production
- Species extinctions
- “Tropical” diseases occurring in areas where they are previously unknown
- Increase in number, duration and intensity of bushfires
What does climate change mean for Australia?
Climate change will have the following physical impacts in Australia:
- Already known as the driest continent, Australian will become drier overall. Some areas may become wetter, but overall most of the continent and especially the southern half, where most of our population lives, will become drier.
- Changes in the intensity of rainfall, tropical storms and cyclones will see greater damage and loss of life, especially as the Australian population is most dense on the coastline.
- The rise in sea level will cause long term concerns. However, if more intense storms coincide with high tides, temporary inundation of populated coastal areas and damage to infrastructure may become more common.
- Agricultural production, a major segment of the Australian economy, could decline.
- Tropical diseases such as Dengue Fever could become more widespread.
- Bushfires could become more common, burn longer and more intensely, resulting in loss of life, loss of infrastructure and loss of environmental resources.
In Australia, the approach, quite sensibly, has always been to exploit the cleanest and closest water source. Typically this meant capturing runoff in large dams, in hilly or mountainous regions upstream of our major cities. The water quality in such large storages is quite good and the water can often flow under gravity to the city downstream in the valley.
Climate change means that rainfall will decrease and that rainfall events will be more intense but more sporadic.
Runoff will only occur when rain falls on already wet catchments. Climate change models predict that rainfall over much of Australia may fall by 10%. However, the probability that this reduced rainfall will fall on already wet catchments, generating runoff, is much less. Modelling indicates a 10% reduction in rainfall will see a 40% reduction in runoff. Another issue, already evident in Australia, is that bushfires and intense storms can result in runoff that causes serious degradation of water quality in the storage dams.
With the existing dams now supplying less water, the water industry will have to go further afield to seek out poorer quality water sources, sources that would have been rejected in the past.
The problem with this is that these new water sources are expensive because of the cost, particularly of energy, to treat them and the cost, again in energy, to transport them to the cities. These high energy costs are also likely to increase sharply in price due to the economic impact of climate change.
Some of these new sources could be stormwater, sewage and even seawater. The adoption of these new sources will see a big increase in water costs over time. Until recently it was common for water to be available to city dwellers for less than one dollar a tonne on demand. In the future, it is likely there will be a major shift in the cost of water, to reflect these new higher cost water sources, and to replace cheap coal-based energy used to source and treat this water, with more expensive but renewable energy.