Changes to Earth's climate and ecosystems will hit the world's poor the hardest, according to a report released Friday by the Intergovernmental Panel on Climate Change. Two of the report's lead authors, Michael Oppenheimer and Joel Smith, discuss the science and politics behind the findings.
The United Nations (UN) top climate panel say Australia and small island states in the Pacific will suffer extensively, but differently, from looming climate change while New Zealand farmers may reap some benefits.
The picture is given in a major report issued in the Belgian capital by the UN's Intergovernmental Panel on Climate Change (IPCC).
It is the second report released by the IPCC this year.
The report says the impacts of climate change this century will vary according to the size of the world's population, energy use and the level of greenhouse gases in the atmosphere, which determines the rise in global temperature.
It found the most vulnerable ecosystems are the Great Barrier Reef, south-west Australia, the Kakadu wetlands, rainforests and alpine areas, many of which are world heritage sites.
Invasive species and habitat loss, species extinction - and the resultant loss in tourism - are risks that are "virtually certain" to increase in Australia and New Zealand.
The report found water problems that already plague south and east Australia are "very likely" to increase by 2030 and river flow from Australia's Murray-Darling basin could fall by 10-25 per cent by 2050.
It warned that increased danger from forest fire, damage to major infrastructure and power blackouts during the summer months are likely to increase in south and east Australia, placing elderly at greater risk of heat-related illnesses.
It also stated coastal development will place lives and property at risk from sea level rise and storms.
"By 2050, there is very likely to be loss of high value land, faster road deterioration, degraded beaches and loss of items of cultural significance," the report said.
It found that by 2050, agriculture and forestry product likely to be reduced over "much" of south and south-east Australia and parts of east New Zealand, but in the south and west of New Zealand, crop yields are likely to increase, benefiting from higher levels of carbon dioxide in the air and warmer and wetter winters.
Pacific Islands
The report also found a rise in sea level and increase in sea water temperature will accelerate beach erosion and degrade natural defences such as mangroves and coral reefs on the Pacific islands, in turn hitting tourism.
Port facilities at Suva in Fiji and Apia in Samoa could be swamped by a rise of half a metre in sea level combined with waves associated in one-in-a-half-century cyclone.
The report predicted that without help to adapt to the threat, farming production on the islands will fall by between 2 to 18 per cent by 2030.
It also says warmer temperatures and decreasing water resources will increase the burden of diseases such as diarrhoea, malaria, dengue, filariasis and schistosomiasis.
World's poor 'hardest hit'
The UN report also says climate change is set to hit poor countries hardest and threaten nearly a third of the world's species with extinction.
"Poor people are the most vulnerable and will be the worst hit by the impacts of climate change. This becomes a global responsibility," the IPCC's chairman, Rajendra Pachauri, declared.
Worsening water shortages in thirsty countries, malnutrition caused by desiccated fields, property damage from extreme weather events and the spread of disease by mosquitoes and other vectors will amount to a punishing bill that is beyond the ability of vulnerable countries, especially in Africa, to pay.
The IPCC says up to 30 per cent of animal and plant species will be vulnerable to extinction if global temperatures rise by 1.5-2.5 degrees Celsius.
Asia faces floods, drought, disease
The report says Asia faces a heightened risk of flooding, severe water shortages, infectious disease and hunger from global warming this century.
The IPCC says the region is confronted by a 90 per cent likelihood that more than a billion of its people will be "adversely affected" by the impacts of global warming by the 2050s.
The major findings include the scenario that 120 million to 1.2 billion people in Asia will experience increased water stress by 2020, and 185 to 981 million by 2050.
Even modest rises in sea levels will cause flooding and economic disruption in densely-populated mega-deltas, such as the mouths of the Yangtze in China, the Red River in China and Vietnam, and the Ganges-Brahmaputra delta in low-lying Bangladesh.
In the Himalayas, glaciers less than four kilometres long will disappear entirely if average global temperatures rise by 3 degrees Celsius.
Arctic Ice
The IPCC report says Arctic ice will extensively disappear and some far-northern lands will lose much of their permafrost this century, while the situation for Antarctica is largely unclear.
"The polar regions are increasingly recognised as being a) geo-politically and economically important; b) extremely vulnerable to current and projected climate change; and c) the regions with the greatest potential to affect global climate and thus human populations and biodiversity," it said.
For the polar regions, the report found that by 2100, the extent of Arctic sea ice could shrink by 22-33 per cent, depending on the emissions scenario.
Arctic glaciers, ice caps and the Greenland icesheet will suffer "important reductions" in thickness and range, but this magnitude is difficult to predict.
Also, land ice loss from the Antarctic peninsula, which has had one of the highest observed increases in temperature anywhere in the world, will continue.
Uncertainty surrounds the situation of Antarctic icesheet, where most of the world's freshwater is locked up.
There is evidence of deglaciation on the west Antarctic icesheet, but some experts suggest this could be a lingering result of the last Ice Age, some 12,000 years ago, rather than recent man-made global warming.
As for the east Antarctic icesheet, some data say it is unchanged, others say it is in fact thickening.
