Australia’s land and oceans have continued to warm at unprecedented rates in response to the highest levels of carbon dioxide in the atmosphere in the past 800,000 years.


Released by the CSIRO and the Bureau of Meteorology, the State of the Climate 2012 report, a yearly summary of Australia’s long-term climate trends.


CSIRO Chief Executive, Dr Megan Clark, said the latest analysis is a clear indicator of growing levels of carbon dioxide, but noted that levels vary significantly from one year to the next.


“Much of Australia may have lurched from drought to floods since the previous State of the Climate, but this has occurred against a backdrop of steadily increasing air and ocean temperatures and rising sea levels. What’s more, the rate of change is increasing.


“The fundamental physical and chemical processes leading to climate change are well understood, and CSIRO and the Bureau of Meteorology observations demonstrate that change is occurring now,” said Dr Clark.


Bureau of Meteorology Acting Director, Dr Rob Vertessy, said this updated summary was based on improved understanding drawn from detailed analysis of our national climate record, which goes back more than a hundred years.


“Ground, ocean and satellite based observations are giving us highly consistent observations of this warming trend. State of the Climate 2012 confirms that each decade has been warmer than the previous decade since the 1950s, with an increase in the number of warm nights, and more monthly maximum temperature records being broken.


“CSIRO and the Bureau of Meteorology will continue to provide observations, projections, research, and analysis so that Australia’s responses to the challenges of a changing climate are underpinned by robust scientific evidence of the highest quality,” said Dr Vertessy.


The report found a general trend towards increasing monsoonal rainfall across Australia’s north, while recording a decline in late autumn and winter rainfall across southern Australia.


Sea-levels have continue to rise at rates equal or greater than expected global average with sea-surface temperatures increasing faster than the global average.


The report documents the annual growth in fossil-fuel CO2 emissions and other greenhouse gasses, finding that CO2 concentration of the atmosphere had risen to around 390 parts per million in 2011. The report found the past decade has seen a three precent increase in concentration,  which is projected to contribute significantly to further global warming.


According to historical data, each decade has been warmer than the previous since the 1950’s, with the average daily maximum temperature increasing by 0.75 °C since 1910, and average mean temperatures increasing by 0.9 °C over the same period.


 The report also found that the global-average mean sea level for 2011 was 210 mm above the level recorded in 1880, rising faster between 1993 and 2011 than during the 20th century as a whole.


The heat content of the world’s oceans has increased during recent decades, increasing the volume of ocean waters and contributing to sea-level rise, with Australia’s sea-surface levels increasing faster than the global average.


The report concluded that average temperatures are projected to rise by between 1.0 to 5.0 °C by 2070, while finding that the number of droughts is expected to increase in southern Australia and are also expected to increase in intensity.