Professor Lesley Hughes, a lead author of the study. Photo: Tamara Dean
Australia's multibillion-dollar mining, farming and tourism industries all face significant threats as worsening global warming causes more dangerous and extreme weather, the world's leading climate science body will warn.
A final draft of a five-year assessment by the UN's Intergovernmental Panel on Climate Change, seen by Fairfax Media, details the global impacts of intensifying climate change, including the displacement of hundreds of millions of people, reduced crop yields and the loss of trillions of dollars from the global economy.
The report is the second part of the IPCC's fifth major assessment, and focuses on climate change's impacts and how the world might adapt. It will be finalised at a meeting in Japan next weekend before release on March 31.
The draft Australasia chapter outlines significant local threats if human-caused climate change is allowed to get worse, in particular that fire seasons, especially in southern Australia, will extend in high-risk areas.
There is significant risk of increased damage and death from heatwaves caused by more frequent extreme high temperatures. Flood risks would be worse, with the draft report warning of increasing damage from inundation.
The draft says these new extremes imply Australia's mammoth mining industry will be increasingly vulnerable without adaptation measures. It points out the loss of coal export revenue of $5 billion to $9 billion when mines were flooded in 2011.
Tourism faces major threats, the draft says. The Great Barrier Reef - with an estimated $51.4 billion in revenue to 2100 - is expected to degrade under all climate change scenarios, reducing its attraction to visitors.
Australia's $1.8 billion skiing industry is identified as most negatively affected, with little option for it to counteract threats such as retreating snow. Maintaining skiing conditions until at least 2020 would require $100 million in investment in new snow guns and water supplies.
A 4 per cent reduction in the gross value of beef, sheep and wool is expected with 3 degrees of warming above the 1980-99 baseline. Dairy output is projected to decline in all regions, except Tasmania, under 1 degree of warming by 2030.
Of the major risks identified for Australia, the draft says the loss of high-altitude ecosystems and deterioration in coral reefs appear difficult to avoid, even with effective global cuts to greenhouse gas emissions and adaptation. It finds modelling shows the range of many wildlife species will contract, including koalas, platypus and banksia.
Jean Palutikof, a review editor of the assessment and director of Australia's National Climate Change Adaptation Research Facility, said while adaptation measures were important, there were limits to what the world could achieve, and it was important to cut global emissions to ensure thresholds were not reached.
''It is quite black-and-white there is a risk we will go beyond the limits of the natural environment and human society to adapt to the climate,'' Professor Palutikof said.
A spokesman for Environment Minister Greg Hunt said the government recognised the importance of adapting to climate change, pointing to the refunding of the research facility, which it has asked to ''focus on putting practical adaptation information in the hands of decision-makers so we can build a stronger and more resilient Australia''.
Future may be fraught as rising tides and hunger drive millions from homelands
The world is hungry and increasingly so. Demand for the three staple food crops – rice, wheat and maize – is expected to grow by 14 per cent every decade until 2050.
Meeting that demand will be hard at the best of times. CSIRO’s Mark Howden, a lead author of the food security chapter in the report, says the yields of food produced by most primary crops is presently growing by only about 1 per cent a decade.
The draft IPCC assessment finds global warming will result in average global crop yields declining by up to 2 per cent a decade. Dr Howden says food crops will remain relatively stable with less than 1 degree of warming. But as temperatures rise above that they will feel the heat. And the more heat, the less crops will be produced.
The nightmare security scenario envisaged under climate change is a war between the bigger nations and millions of refugees driven from their homelands by rising seas.
Melbourne University political geographer Professor Jon Barnett is a lead author of the new security chapter in the draft report. He says the published evidence makes clear that extreme weather will displace large numbers of people. But it also shows people tend to return once a threat subsides, meaning displacement is often temporary.
The report says by 2100, without help, hundreds of millions will be affected and displaced by coastal flooding and land loss. The real concern will be the poor and vulnerable who will have no means of escape.
The IPCC assessment also looks at whether climate change will cause more armed conflicts, an area Professor Barnett says is deeply contested. Climate change could also shape security policy and heighten tensions between nations over such issues as shared water resources and fish stocks.
At the top of Australia’s mountains, the world is closing in. As the planet warms, snow is disappearing and the montane environment is receding. Macquarie University biologist Lesley Hughes, a lead author of the Australasian chapter, says habitat contraction is one of the key challenges already emerging as a result of climate change.
She says if warming intensifies during the next decades the overall global picture for ecosystems, plants and animals is bleak. A leaked draft of the report concludes that many species are already shifting their range, seasonal activities, migration patterns and interactions in response to climate change. Professor Hughes says the main driver of extinction will continue to be land-use change up to 2 degrees of warming; any higher and climate change will become the predominant factor.