Climate likely to send tropical creatures south

Crocodiles could be among creatures following a newly expanded tropical climate. Photo / Getty Images

Crocodiles, cane toads and the mosquito-borne dengue virus may start cropping up in more southerly regions of Australia as the tropics expand due to climate change.

The tropics are expected to grow by about 200km every 25 years which could lead to Perth, Sydney, Adelaide and possibly Melbourne becoming hotter and drier by the turn of the century.

The predictions form part of a 500-page landmark State of the Tropics report which was unveiled by Myanmar's opposition leader Aung San Suu Kyi in Yangon last night. Twelve research centres worldwide collaborated on the report, including James Cook University in Queensland.

Dr Joanne Isaac, a researcher at JCU's Centre for Tropical Biodiversity and Climate Change, collaborated on an essay for the report.

"If you think about pushing the tropics south in Australia 200km it means, for example, that the conditions in say Cairns will be further south," she said. "By the turn of the century I think we'll definitely see some very significant changes.

"We'll probably have a climate that's pretty different to the one we remember."

The primary drivers of the expansion are likely greenhouse gases, black carbon, aerosols and other man-made pollutants.

Although southerners may be happy about the prospect of more warmer, sunnier days ahead, Isaac warns Australia faces big challenges as it adapts to the climatic shift.

As those areas in the subtropical zone become drier and hotter water resources may be strained, affecting highly populated areas, the agriculture industry and biodiversity. She says there's evidence some plants and animals have already started moving south as they track their preferred climate, although it appears they're lagging behind the rate of tropical expansion.

There were a couple of predictions that animals like crocodiles may track further south if the water is warmer, she said. Also, cane toads would shift with the climate which would impact some native species.

Drought, cyclones and tropical disease could become more prevalent in the south, while flooding may plague the north. Australia will need to ensure policies are in place to cope, including changing building codes in areas which will be impacted by cyclones and more severe flooding.

The report is the first analysis of the world's tropics and aims to shine a light on environmental, social, health and economic factors affecting the area.

- AAP