Marohasy worked as a field biologist in Africa and Madagascar during the 1980s and 1990s, and has a number of published papers in science journals. In 1997 she switched from researcher to environment manager with the Queensland sugar industry. In 2001, she started to develop an interest in environmental campaigns and, in particular, claiming that there are anomalies between fact and perception regarding the health of coastal river systems and the Great Barrier Reef. In July 2003, she became director of the environment unit at the Institute of Public Affairs.
While head of the Environment Unit at the Institute of Public Affairs, Marohasy compiled a backgrounder titled Myth and the Murray - measuring the real state of the river environment which was published by the Institute in December 2003. The Institute received a $40,000 donation from Murray Irrigation Limited at that time. This paper is quoted in the Interim Report of the Inquiry into future water supplies for Australia’s rural industries and communities of the House of Representatives Standing Committee on Agriculture, Fisheries and Forestry, March 2004. At a science round table of the committee, when asked for her views on how much water should be returned to the River Murray, Marohasy argued that there was no need for additional flows at that time and that we should test the results of current environmental measures before committing to more. Marohasy was instrumental in establishing a joint programme with the Institute of Public Affairs and the University of Queensland, funded by Western Australian philanthropist, Bryant Macfie.
Public position on global warming
In an Australian Broadcasting Corporation interview she stated that... "t's not clear that climate change is being driven by carbon dioxide levels...whether or not we can reduce carbon dioxide levels, there will be climate change". On the Australian Broadcasting Corporation Radio National program, Ockham's Razor, Marohasy said in 2005... "I agree with Professor Flannery that we need to reduce atmospheric carbon dioxide levels". In an interview on the Australian Broadcasting Corporation Radio National program, Counterpoint, she claimed recent cooling by starting with the extreme temperature peak of the 1998 El Niño event. She said that... "there has been cooling if you take 1998 as your point of reference. If you take 2002 as your point of reference then temperatures have plateaued. This is certainly not what you'd expect if carbon is driving temperature because carbon dioxide levels have been increasing but temperatures have actually been coming down over the last ten years....very unexpected not something that is being discussed. It should though be being discussed because it is very significant".
2017 GeoResJ manuscript
A paper that Marohasy co-authored with her Institute of Public Affairs colleague John Abbot, titled "The application of machine learning for evaluating anthropogenic versus natural climate change," was made available online on 5 August 2017. It was published in GeoResJ, a quarterly peer-reviewed journal in Earth Sciences that began publishing in 2014 and is to be discontinued from January 2018. Marohasy wrote about her findings in The Spectator Australia and in her blog, declaring that most of the warming that has occurred could be natural. "ven if there had been no industrial revolution and burning of fossil fuels, there would have still been warming through the twentieth century — to at least 1980, and of almost 1 °C," she wrote. The paper also questions the equilibrium climate sensitivity, which relates to the extent of warming associated with a doubling of atmospheric levels of carbon dioxide. Abbot and Marohasy estimate a 0.6 °C temperature rise would result, well below the range of 1.5 to 4.0 °C estimated in reports from the Intergovernmental Panel on Climate Change.
