As Prime Minister Kevin Rudd heads off to major international meetings with climate change high on the agenda this week, a new report reveals that seasons which were once distinct are shifting, destroying harvests and causing widespread hunger.

This is just one of the multiple impacts of climate change taking their toll on the world's poorest people, according to the Oxfam report 'Suffering the Science - Climate Change, People and Poverty'.

The report's release comes ahead of the G8 Summit in Italy (which starts Wednesday) and the Major Economies Forum (Thursday), both of which Prime Minister Kevin Rudd is attending. Combining the latest scientific observations on climate change with evidence from the communities Oxfam works with in almost 100 countries around the world, the report reveals how the burden of climate change is already hitting poor people hard.

"Climate change is the central poverty issue of our times," said Oxfam Australia climate change policy advisor Julie-Anne Richards. "Climate change is happening today and the world's poorest people, who already face a daily struggle to survive, are being hit hardest. The evidence is clear - the human cost of climate change is as real as any redundancy or repossession notice.

"In Australia, we are staring down the barrel of greater droughts, more extreme fire days, and the prospect of diseases such as dengue fever expanding into new regions. Such impacts are already being felt by people in developing countries."

The report warns that, without immediate action, 50 years of development gains in poor countries will be permanently lost. It predicts that climate-related hunger could be the defining human tragedy of this century. Suffering the Science outlines evidence of how climate change is affecting every issue linked to poverty and development today, including:

- HUNGER: Rice and maize, two of the world's most important crops on which hundreds of millions depend, particularly in Asia, the Americas and Africa, face significant drops in yields even under mild climate change scenarios. Maize yields are forecast to drop by 15 per cent or more by 2020, in much of sub-Saharan Africa and in most of India. One estimate puts the loss to Africa at US $2bn a year.

- AGRICULTURE: New research based on interviews with farmers in 15 countries across the world reveals how once distinct seasons are shifting and rains are disappearing. Farmers from countries including Bangladesh, Uganda and Nicaragua, who are no longer able to rely on generations of farming experience, are facing failed harvest after failed harvest.

- HEALTH: Diseases such as malaria and dengue fever that were once geographically bound are creeping to new areas where populations lack immunity or the knowledge and healthcare infrastructure to cope with them. It is estimated that climate change has contributed to an average of 150,000 more deaths from disease per year since the 1970s, with over half of those happening in Asia. In Singapore, Bangkok and the cities of Indonesia, dengue fever rates have risen continually over the past 20 years.

- DISASTERS: Disasters including mega fires and storms are on the rise and could triple by 2030. Hurricanes and cyclones throughout the world in 2005 cost a record US $165 billion, and the insurance industry says that climate change will make the situation worse, particularly for poor people who have no access to insurance. Meanwhile, research shows that for every $1 spent on hazard reduction or disaster preparedness, an estimated $4 is saved.

- WATER: Water supplies are becoming so acutely challenged that several cities including Kathmandu and La Paz, which are dependent on the Himalayan and Andes glaciers, may soon be unable to function.

- DISPLACEMENT: An estimated 26 million people have been displaced as a direct result of climate change and each year a million more are displaced by weather related events. Island communities from Vanuatu, Tuvalu and the Bay of Bengal have already been forced to move because of sea level rise.

- LABOUR: Rising temperatures will make it impossible for people to work at the same rate on hot summer days without serious health impacts, with huge ramifications for labourers paid by the hour and the wider economy. Tropical cities such as Delhi could see a drop in worker productivity of as much as 30 per cent.

A survey of top climate scientists, also published by Oxfam today, said poor people living in low-lying coastal areas, island atolls in the Pacific, mega deltas and farmers throughout the world, are most at risk from climate change because of flooding and prolonged drought. The scientists, all contributors to the International Panel on Climate Change (IPCC), named South Asia and Africa as climate change hotspots.

Many scientists are now sceptical as to whether the world can limit global warming to 2=B0C because they do not believe politicians are willing to agree the necessary cuts in carbon emissions, the report says. Two degrees of warming is considered to be "economically acceptable" to rich countries, however whilst all countries, including Australia, would suffer, it would mean a devastating future for 660 million people throughout the developing world.

Professor Diana Liverman, a leading contributor to three IPCC Assessment Reports and a member of the National Academy of Sciences Committee, which advises the US Government on climate change, said if countries did not make deep cuts in emissions now, the changing climate would bring heat stress, sea level rise and more extreme drought and floods.

"Organisations like Oxfam can try and help people adapt to climate change but without a serious effort to reduce warming, and in the absence of international funds for adaptation, the food, water, health and livelihoods of millions of people will be at risk," Ms Liverman said.

Oxfam Australia is calling for the Australian Government to show leadership in delivering a fair and safe global deal to tackle climate change, as only political commitment at the highest level can prevent a human catastrophe. Rich industrialised countries, which created the climate crisis and have the resources to tackle it, must cut their emissions by at least 40 per cent on 1990 levels by 2020 and mobilise $187 billion per year to fund emissions reduction and adaptation in the developing world.

"Australia must show leadership at the UN climate negotiations and contribute to a global climate deal which has the needs of the world's poorest people at its heart," Ms Richards said.

Survey of top climate scientists: 330 scientists who contributed to the IPCC Fourth Assessment Report; Working Group II on Impacts, Adaptation and Vulnerability, were invited to take part in an on-line survey. 12.73 per cent of scientists responded.

For more information, personal stories and interviews, please contact:

Laurelle Keough on 0409 960 100 or laurellek@oxfam.org.au