Weather and water chaos
Temperatures
The Earth's average temperature has warmed by about 0.76 of a degree over the past 100 years, with most of this warming occurring in the past 20 years .
This temperature rise appears small but small rises in temperature translate into big changes for the world's climate.
By 2070, the warming is likely to be 1-6°C over most of Australia. The greatest warming will occur in spring and least in winter, with most warming in the north-west occurring in summer . The rise in average temperature will also lead to large changes in the frequency of extremely hot and cold days.
Droughts and floods
Changes in rainfall patterns and increased evaporation, combined with El Niño events, are likely to produce more frequent and prolonged drought periods throughout Australia.
Climate models suggest that drought could be as much as 20% more common by 2030 over much of Australia and up to 80% more common in south-western Australia by 2070.
Major floods that used to happen only once in 100 years are likely to take place every 10 or 20 years.
Storms and cyclones
Global warming could lead to more intense storms and cyclones. The CSIRO states that tropical cyclone wind speeds may increase by 5-20% by the end of the century.
It is also predicted that more intense tropical cyclones will produce more severe oceanic storm surges, which are likely to be further exacerbated by sea level rise.
Glaciers and sea level rises
Eighty-five percent of the Earth's glaciers are retreating at an unprecedented rate, changing the entire ecology of mountain habitats and reducing the available water supply.
Land-based glacial melting is also contributing to rising sea levels, and rising ocean temperatures are causing seas to expand.
According to the CSIRO, sea levels are predicted to rise between 9 and 88 centimetres by 2100 or 0.8-8 cm per decade.
El Nino and climate
El Nino is a climatic phenomenon based on interactions between oceans and the atmosphere. In Australia El Nino is associated with drier than normal conditions with three out of four Australian droughts occurring during El Nino years.
Each El Nino event occurs about every 4-7 years and typically lasts for 12-18 months. However El Nino events have in recent years increased in frequency and are often not – as was usual in the past – interrupted by La Nina events (the opposite climatic cycle).
Climate Witnesses in Fiji and the Sundarbans are already reporting changes to their daily lives from these climatic events.
