Seasonal Climate Outlook Message for September to December 2008

The bottom line

23 September

What is climate change?

As climate change attracts a lot of interest I thought I'd give a brief background on climate change and global warming (greenhouse effect).

The greenhouse effect is a natural phenomenon. Naturally occurring greenhouse gases such as water vapour, carbon dioxide, methane and nitrous oxide trap some of the heat being radiated back into by the earth's surface. The earth is heated during the day by incoming solar radiation, and cools (more on clear nights) at night.

It is greenhouse effect that makes earth habitable for humans, and is part of the reason planets/ satellites without an atmosphere, like Mars or the moon, are so cold. Without the greenhouse effect of the Earth's atmosphere the surface would be around 33 degrees Celsius cooler. That's means that instead of an average surface temperature of plus 15 degrees Celsius the temperature would be minus 18 degrees Celsius!

In addition to the Earths natural greenhouse effect there is an increasing body of evidence that shows changes to the atmosphere have enhanced the natural greenhouse effect and resulted in a warming trend in many areas. The changes to the atmosphere are the result of burning fossil fuels such as coal and oil for energy production and transport, and changing land use patterns (such as urbanisation). These activities lead to an increase in carbon dioxide levels and other greenhouse gases in the atmosphere.

It is also worth noting that as our climate is influenced by many natural phenomena as well as any human induced environmental changes, and that the climate will always be in a state of change.

Natural phenomena impacting climate include the annual cycle (seasons), El Nino/Southern Oscillation, Pacific Decadal Oscillation, North Atlantic Oscillation, volcanic eruptions, fluctuations in solar irradiance, changes in orbital cycles and variations in ocean, land and polar ice.

Human induced, or anthropogenic, drivers of climate change include changes in land use, urbanisation, and anthropogenic sources of atmospheric greenhouse gases, aerosols and other pollutants.

Regardless of the causes of climate change it is important is to consider is what impact climate change will have on business, agriculture and regional communities. This does not mean shutting up shop. What it does mean is that now is the time to look at how to adapt our industries and practices to handle these potential changes.

Queensland climate change projections are available at www.climatechange.qld.gov.au/ . Current CSIRO climate change reports are available at www.dar.csiro.au/impacts/consult.html . For more information try www.ipcc.ch/ where the International Panel on Climate Change reports are available, or to look at the interim Garnaut report go to www.garnautreview.org.au/

The thirty day average of the SOI as of 23 September was plus 17.1.