Climate change is monitored by Australia’s national science and weather agencies, the CSIRO and Bureau of Meteorology. The latest research found that:
• Australia’s climate has warmed in both mean surface air temperature and surrounding sea surface temperature by around 1 °C since 1910.
• The duration, frequency and intensity of extreme heat events have increased across large parts of Australia.
• There has been an increase in extreme fire weather, and a longer fire season, across large parts of Australia since the 1970s.
• May–July rainfall has reduced by around 19 per cent since 1970 in the southwest of Australia.
• There has been a decline of around 11 per cent since the mid-1990s in the April–October growing season rainfall in the continental southeast.
• Rainfall has increased across parts of northern Australia since the 1970s.
• Oceans around Australia have warmed and ocean acidity levels have increased.
• Sea levels have risen around Australia. The rise in mean sea level amplifies the effects of high tides and storm surges.
Climate change in Victoria
The results from the 2013 State of the Environment report are set out below.
- Average temperatures in Victoria have risen by about 0.8°C since the 1950s and the severity, duration and frequency of heatwaves have increased.
Victorian mean temperature anomaly, 1910-2012
- There has been a decline in autumn, winter and spring rainfall over the past two decades, and fewer very wet years.
- Between 1997 and 2009, Victoria experienced a record-breaking 13-year drought and the annual inflow to Melbourne’s dams dropped by almost 40%. Victoria experienced its highest summer rainfall on record in 2010–11, leading to major flooding that affected a third of Victoria.
- Between 1989 and 2011, emissions increased by 12%, with stationary energy emissions increasing by 42%.
- Between 2000 and 2009, fires released 70 million tonnes of carbon dioxide, around 6% of the total emissions over the period. Large fires in 2007 released the equivalent of 20% of the total greenhouse gas emissions for that year..
- Per capita greenhouse gas emissions decreased from 24 tonnes in 1989–90 to 21 tonnes in 2010–11. However, this decrease has been offset by population growth. In 2010–11, Victoria emitted a total of the carbon dioxide equivalent of 118 million tonnes of greenhouse gas (118 million Mt CO2-e), or 124 Mt CO2-e,when land use, land-use change and forestry are excluded. Victoria is responsible for 21% of Australia’s total net emissions.
- Carbon dioxide is the most significant greenhouse gas, contributing over 80% of total Victorian emissions in 2009. The majority of carbon dioxide emissions come from industry, transport and energy generation. Between 2000 and 2009, fires released 70 million tonnes of carbon dioxide, around 6% of the total emissions over the period.
Victorian ecosystem contribution to global greenhouse gas balance and carbon storage
- In 2010, Victoria’s carbon stock for publicly managed forested land was estimated at between 680 and 775 million tonnes of carbon (or up to 2.8 billion tonnes of carbon dioxide equivalent). This represents about 25 years of Victoria’s total annual greenhouse gas emissions.
- Climate variation and catastrophic bushfire events can have considerable impacts on carbon stocks.
Projected climate trends in Victoria
- By 2030 warming in Victoria is likely to range from 0.6°C to 1.2°C on 1990 temperatures and by 2070 from 0.9°C to 3.8°C.
- Runoff into most of our waterways is projected to decrease between 5 and 45% by 2030 and between 5 and 50% by 2070.
- Fire risk is forecast to increase substantially in Victoria, with the number of very high or extreme fire danger days expected to increase by up to 25% by 2020 and up to 230% by 2050.
- By 2070 drought frequency is likely to increase by between 10 and 80% in the southern half of the state and by between 10 and 60% in the northern half.
- More frequent extreme weather events are predicted; a current one in 100 year extreme storm surge could occur around every five years by 2070.
Sea-surface temperature and sea-level rise
- Annual sea-surface temperatures in south-eastern Australia increased at a rate of 0.023°C per year, around four times the global ocean-warming average.
- Since 1993, Victoria’s sea-level rise has been similar to global averages of 3 mm per year.
Image: Tim J Keegan