Australia's multibillion-dollar mining, farming and tourism industries 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 (IPCC) - seen by Fairfax Media - details a litany of global impacts from 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 its release on March 31.
The final draft Australasia chapter also outlines significant local threats if human-caused climate change gets worse, in particular high confidence that fire seasons, particularly in southern Australia, will extend in high-risk areas.
There is also significant risk of increased damage and death from heatwaves resulting from more frequent extreme high temperatures. Flood risk too would be worse.
The draft says these new extremes imply Australia's mammoth mining industry is increasingly vulnerable without adaptation measures. The report points to significant loss of coal exports revenue of $5 billion to $9 billion when mines were flooded in 2011.
Tourism also faces some significant threats, the draft says. The Great Barrier Reef is expected to degrade under all climate change scenarios, reducing its attractiveness to visitors.
Australia's $1.8 billion ski industry is identified as most negatively affected, with little option for it to counteract threats.
For Australian farming a 4 per cent reduction in the gross value of beef, sheep and wool is expected with 3 degrees of warming above a 1980-99 baseline.
Dairy output is projected to decline in all regions, except in Tasmania.
Out of the major risks identified for Australia in the draft, the loss of montane ecosystems and changes in coral reefs, appear to be very difficult to avoid. The draft also finds modelling consistently indicated the range of many wildlife species will contract.
And there is high confidence climate change is already affecting Australia's oceans, with climate zones and species shifting hundreds of kilometres southwards.
Professor 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 do and it was important to cut global emissions to ensure these thresholds are not reached.
''I think 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'' she said.
A spokesman for Environment Minister Greg Hunt said the government recognised the importance of adapting to the impacts of climate change, pointing to the refunding of the National Climate Change Adaptation 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, more resilient Australia''.
The world is hungry and increasingly so. Demand for the three staple food crops - rice, wheat and maize - is expected to grow 14 per cent a decade to 2050.
Meeting that demand will be hard at the best of times. CSIRO's Dr Mark Howden says the food produced (yields) by most primary crops is presently growing by only about 1 per cent a decade.
Then there is climate change. The draft IPCC assessment finds with global warming average global crop yield will decline by up to 2 per cent a decade .
Dr Howden is a lead author of the food security chapter in the report. He 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 produce.
''Confidence that things will get more and more negative is stronger and stronger as we go out to higher temperatures,'' he says.
More extreme weather will also mean the amount of food produced will vary wildly year-on-year.
The draft findings of the fifth assessment differ from the IPCC's last report, which found crop losses in some areas would be offset by gains elsewhere. Five years on and more negative impacts are now being observed than positive.
Dr Howden says adaptation can improve yields by about 10 to 15 per cent above what they would otherwise have been - enough to feed a billion people. The draft says adaptation can be effective at about two degrees of warming, but at four degrees the gap between production and demand will become increasingly large in many regions, even with adaptation.
The work to be able to adapt food production to a hotter and more variable world must begin now, Dr Howden says. One example is the need to breed varieties that can handle the new climate, while to date we breed for historic conditions.
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. The animal and plant species that call it home, such as the mountain pygmy-possum, have a significant problem - their chance of extinction is growing.
Macquarie University biologist, Professor Lesley Hughes, says habitat contraction is one of the key challenges emerging as a result of climate change.
Professor Hughes is a lead author of the Australasian chapter. She says if warming intensifies over the coming decades the overall global picture for ecosystems, plants and animals is bleak. A leaked draft of the report concludes many species are already shifting their range, seasonal activities, migration patterns, and interactions.
''There are lots of species that have proved to be very sensitive to warming of even less than 1 degree,'' Professor Hughes says.
''In some cases species have moved several hundred kilometres to cooler areas towards the poles, particularly in the marine world, where there are less barriers to movement than on land.''
She says that at up to 2 degrees of warming, the main driver of extinction, will continue to be land-use change, but at any higher rate of warming, climate change will become the predominant factor.
Professor Hughes says most species cannot evolve at the same speed as the planet is changing, and there is little humans can do to help out.
Wars between great nations and millions of refugees driven from home by rising seas. These are the nightmare security scenarios envisaged under climate change.
In a sign of concern about global warming's security impact the Intergovernmental Panel on Climate Change has for the first time assessed what problems may emerge.
Professor Jon Barnett, a political geographer at Melbourne University, is a lead author of the security chapter. He says published evidence is 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.
What about long-term deterioration, such as sea level rise? The draft report says by 2100, without help, hundreds of millions of people will be displaced by coastal flooding and land loss.
Will that mean great numbers of refugees fleeing to other countries? Professor Barnett says there is no clear evidence for that. And the real concern will be the poor and vulnerable who will have no escape means.
''Only some groups have the wherewithal to move as conditions deteriorate. Typically, it is the most vulnerable who are left behind and that is where the greatest social and humanitarian problem is,'' Professor Barnett says.
The IPCC assessment also looks at whether climate change will cause more armed conflicts, an area which he says is deeply contested. The draft assessment concludes climate change will indirectly increase the risk of conflict by exacerbating factors that cause violence, such as poverty and economic shocks.
While the link between climate change and war is not clear, it may shape security policy and heighten tensions between nations over factors such as shared water resources and fish stocks. But Professor Barnett says these can be managed peacefully with strong international institutions.