Climate change and global warming
Our atmosphere - the layer of air that surrounds the earth - contains many gases. Burning fossil fuels, such as oil, coal and gas, clearing forests and the use of manufactured gases such as chlorofluorocarbons have increased the amount of greenhouse gases in the atmosphere.
These gases, of which the most abundant is carbon dioxide, also include nitrous oxide, methane and chlorofluorocarbons. They absorb heat from the sun and create a warmer atmosphere.
Climate change and global warming refer to changes in climate due to human activity and the resultant increasing temperature of the Earth's surface.
The impact of climate change on water resources is the subject of much scientific research. It is difficult to quantify outcomes now, especially at regional and local levels.
Melbourne Water climate change study
In 2003 Melbourne Water commissioned the CSIRO to conduct a detailed study into the likely impact of climate change on our water, sewerage and drainage systems.
Implications of Potential Climate Change for Melbourne’s Water Resources was released in 2005 and identified trends including:
- Increased average and summer temperatures
- Reduced rainfall
- Reduced stream flows
- More extreme events with more hot days, more dry days and increased rainfall intensity during storm events.
The report found many uncertainties around climate change predictions, but the greater Melbourne area could experience:
- Potential average annual temperature increases ranging from 0.3 to1.0°C (mid range 0.5°C) in 2020, and 0.6 to 2.5°C (mid range 1.4°C) in 2050
- A change in average annual rainfall patterns ranging from 0% to minus 5% (mid range minus 2%) in 2020, and between minus 13 % to a possible slight increase of 1% (mid range minus 4%) in 2050
- A reduction in average stream flow into Melbourne’s main reservoirs of between 3% and 11% (mid range 7%) by 2020 and between 7% and 35% (mid range 18%) by 2050
- A reduction in total water supply system yield ranging from 4% to 15% by 2020 (mid range 8%) and from 10% to 40% (mid range 20%) by 2050.
Due to the current 10-year drought, some of our rivers and creeks are experiencing stream flow reductions far in excess of long term climate change prediction.
The volume of greenhouse gases in our atmosphere is increasing, particularly carbon dioxide. Rising temperatures melt snow and ice causing oceans to rise. Greenhouse gases trap some of the sun's heat being reflected from the earth creating a warmer atmosphere. A warmer atmosphere draws more water-vapor into the air which traps even more heat.
Links
- For more information, visit: http://www.dar.csiro.
au/publications/
projections2001.pdf - CSIRO summary of climate change impacts, visit: http://www.marine.
csiro.au/iawg/
impacts2001.pdf