A study led by Clive McAlpine and Jozef Syktus indicates that 150 years of land clearing added significantly to the warming and drying of eastern Australia.
They both work with the University of Queensland, McAlpine at Centre for Remote Sensing and Spatial Information Science and Syktus at the Natural Resources and Water Department (DNRW), and applied CSIRO Mark 3 climate model, satellite data and the DNRW supercomputer in their project.
"Our work shows that the 2002-03 El Nino drought in eastern Australia was on average two degrees Centigrade hotter because of vegetation clearing," McAlpine said.
"Based on this research, it would be fair to say that the current drought has been made worse by past clearing of native vegetation.
"Our findings highlight that it is too simplistic to attribute climate change purely to greenhouse gases.
"Protection and restoration of Australia's native vegetation needs to be a critical consideration in mitigating climate change."
Co-authors are Dr Hamish McGowan, Associate Professor Stuart Phinn and Dr Ravinesh Deo - all of UQ - Dr Peter Lawrence of the University of Colorado and Dr Ian Watterson of CSIRO.
The researchers found that mean summer rainfall decreased by between four percent and 12 percent in eastern Australia, and by four percent and eight percent in southwest Western Australia. These were the regions of most extensive historical clearing.
"Consistent with actual climate trends, eastern Australia was between 0.4 degrees Centigrade and two degrees Centigrade warmer, and southwest Western Australia was between 0.4 degrees and 0.8 degrees warmer.
"Native vegetation moderates climate fluctuations, and this has important, largely unrecognised consequences for agriculture and stressed land and water resources," McAlpine said.
Australian native vegetation holds more moisture that subsequently evaporates and recycles back as rainfall. It also reflects into space less shortwave solar radiation than broadacre crops and improved pastures, and this process keeps the surface temperature cooler and aids cloud formation.
In March this year, a report co-authored by the University of Sydney's Professor Chris Dickman warned that land clearing in New South Wales could see the number of mammal species in the state being halved, More than 104 million native mammals, birds and reptiles hade died or would die as a result of the NSW land clearing between 1998 and 2005, according to the report, released by the World Wildlife Fund.
The number of individual animals killed or likely to die as a result of this approved land clearing included:
• over 11 million mammals with possums and gliders most severely affected, as well as many millions of kangaroos, wallabies, bandicoots, koalas and wombats;
• around 13 million birds comprising mostly woodland and forest birds and including species of honeyeaters and babblers that are under threat of extinction in NSW; and
• more than 80 million reptiles such as skinks and geckos.
Those estimates were highly conservative and did not take into consideration illegal land clearing activities and clearing that is exempt from the approval process, which would add millions more animals to the toll, the WWF said.
"It is possible to state categorically that clearing of large areas of vegetation in New South Wales continues through the exemption of non-remnant vegetation, illegal clearing and clearing of so-called invasive native scrub, despite the 2003 commitment to end broadscale land clearing," WWF-Australia's Director of Conservation, Dr Ray Nias, said.
"NSW clearly needs a more effective approach if it is to stop the loss of wildlife threatened by clearing and fragmentation of native vegetation."