Contributors to climate change report say extinction possibility.
Leading Australian academics have warned that humans could face extinction from massive global health crises, plunging food production, and other damage inflicted on the Earth's life support system by climate change.
Their warning follows the release yesterday of the latest report of the United Intergovernmental Panel on Climate Change, which forecast a catastrophic future for the planet unless urgent action is taken.
Australia was warned in the report of major declines in agricultural productivity, the death of the Great Barrier Reef, more severe heatwaves and bushfire seasons, and storms and flooding of increasing severity and intensity.
Destroyed houses lie in Tacloban city, Leyte province, in the central Philippines,
after last November's devastating Typhoon Haiyan.
But Australian National University Emeritus Professor Anthony McMichael, Canberra University Professor Colin Butler and Canberra University's Associate Dean, Research, Helen Louise Berry say the crucial impact on human life has been sidelined.
At potential risk is the survival of the species.
The three academics were contributors to the report on the impact of climate change on human health.
"Public discussion has focused narrowly on a largely spurious debate about the basic science and on the risks to property, iconic species and ecosystems, jobs, the GDP and the economics of taking action versus taking our chances," they wrote in The Conversation.
Waves broke over Porthcawl Harbour, South Wales, when the UK was battered by high winds and heavy rain in February.
"Missing from the discussion is the threat climate change poses to Earth's life-support system - from declines in regional food yields, freshwater shortage, damage to settlements from extreme weather events and loss of habitable, especially coastal, land.
"The list goes on: changes in infectious disease patterns and the mental health consequences of trauma, loss, displacement and resource conflict.
"In short, human-driven climate change poses a great threat, unprecedented in type and scale, to well-being, health and perhaps even to human survival."
They wrote that over the next few decades climate change would hit mainly in poorer and vulnerable communities already suffering high rates of illnesses such as under-nutrition and diarrhoeal disease.
Researchers in many countries had already reported increases in heat-related illnesses and deaths, changes in the distribution of water-borne diseases and the insects that carry them, and reduced food yields.
By 2100, when according to some computer models the planet will have warmed by an average 4C, "people won't be able to cope, let alone work productively, in the hottest parts of the year.
"Some regions may become uninhabitable," they wrote. "Impacts on mental health could be similarly extreme, further limiting our collective capacity to cope, recover and adapt."
The increasing frequency of extreme heatwaves and bushfires pose significant risks to life, property damage and the economy, with more frequent and intense flooding.
But one of the report's lead authors, Macquarie University Professor Lesley Hughes, said action could still be taken to avoid the worst: "It's not all doom and gloom if we get a wriggle on and do a lot about it."
"This is the critical decade to tackle the cause of climate change and stabilise the climate to avert the most serious risks."
Report paints grim picture
The negative effects of climate change are already beginning to be felt worldwide and yet countries are ill-prepared for the potentially immense effects on food security, water supplies and human health, the United Nations climate report has concluded.
In the most comprehensive study yet into the effects of rising levels of carbon dioxide in the atmosphere, the Intergovernmental Panel on Climate Change warns that global warming could undermine economic growth and increase poverty.
The IPCC found the negative effects of climate change have already extended beyond any potential benefits of rising temperatures. They will worsen if global-average temperatures continue to rise by the expected lower limit of 2C by 2100 and could become catastrophic if temperatures rise higher than 4C. In a blunt and often pessimistic assessment of climate-change effects, the fifth since 1990, the IPCC scientists give a stark warning about what the world should expect if global temperatures rise as predicted without mitigation or adaptation.
"In recent decades, changes in climate have caused impacts on natural and human systems on all continents and across the oceans," says the report released after a final meeting in Yokohama, Japan.
It says climate-change effects this century are tipped to slow economic growth, make poverty tougher, further erode food security, and prolong existing and create new poverty traps, the latter particularly in urban areas and "emerging hot spots of hunger".
"Climate change is happening, there are big risks for everyone and no place in the world is immune from them," said Professor Neil Adger of Exeter University, one of the many lead authors of the report. Nearly 2000 experts from around the world contributed.
How climate change will touch all of us
Crop yields have increased in general over recent decades but the rate of improvement would have been even faster had it not been for climate change. The signature of rising temperatures and heat stress are already showing on yield of wheat and maize, the report says. All aspects of food security are potentially affected by climate change, including food access, utilisation and price stability, it says.
As global temperatures rise, then so does the fraction of the human population that are affected by either water scarcity or river flooding. Climate change over the 21st century is projected to reduce renewable surface water and groundwater resources significantly in most dry subtropical regions.
Loss of species
The risk of plant and animal extinctions increases under all climate change scenarios, but they get worse with higher temperatures. Loss of trees and forest dieback will be a particular problem in a warmer world, the report says. A large fraction of terrestrial and freshwater species face increased extinction risk under projected climate change during and beyond the 21st century, especially as climate change interacts with other stress factors such as habitat modification, over-exploitation, pollution and invasive species, it says.
Coral reefs and shelled marine creatures, especially the smaller animals at the base of the marine food chain, are at special risk of rising carbon dioxide concentrations, which are causing the oceans to become more acidic and less alkaline. This in turn will affect human populations that rely on sea fish as a food source.
Economic losses due to climate change are difficult to assess and many past estimates have not taken into account the catastrophic changes that could result from the climate passing a tipping point. Losses, however, are more likely than not to be greater, rather than smaller, than an estimated range of between 0.2 and 2 per cent of global income loss due to a temperature rise of about 2C.
Climate change can indirectly increase the risk of violent conflicts, such as civil wars, by amplifying the well-documented drivers such as poverty and economic shocks. Climate change will also increase the risk of unplanned displacement of people and a change in migration patterns, the report says.
1 The IPCC report says global warming is driving humanity toward a whole new level of many risks.
2 "Nobody on this planet is going to be untouched by the impacts of climate change," Intergovernmental Panel on Climate Change chairman Rajendra Pachauri said.
3 Killer heat waves, bushfires, droughts and deadly flooding highlight how vulnerable humanity is to extreme weather. The dangers are going to worsen.
4 The highest level of risk would first hit plants and animals. Risks will hit farmers and big cities. Some places will have too much water, some not enough. Other risks mentioned involve the price and availability of food, some diseases, financial costs and security.
5 Climate change will worsen problems that society already has, such as poverty, sickness, violence and refugees. It will act as a brake slowing down the benefits of a modernising society, such as regular economic growth and more efficient crop production.