According to the Intergovernmental Panel on Climate Change, Asia will be hit hard as the world's climate changes in the coming decades, including threats that are "too alarming to contemplate," said Achim Steiner, executive director of the United Nations Environment Program.

"Unchecked climate change will be an environmental and economic catastrophe, but above all it will be a human tragedy," said Steiner in a statement. "It is absolutely vital that international action is taken now to avoid dangerous climate change."

An extra 130 million people are at risk of hunger across Asia by 2050 because of the world's changing climate, the IPCC report said.

Droughts and flooding will likely increase in Australia and New Zealand by 2030, according to the report, and ecologically rich sites like the Great Barrier Reef and sub-Antarctic islands are also under threat.

A summary of the full, 1,572-page document written and reviewed by 441 IPCC scientists was released last Friday. Further details were unveiled Tuesday in a series of regional press conferences around the world. The report, the second of four to be released this year, tries to explain how global warming is changing life on Earth.

The report suggests a 2 degree Celsius (3.6 degree Fahrenheit) increase in air temperatures could decrease rain-fed rice yields by 5 percent to 12 percent in China.

In Bangladesh, rice production may fall by 10 percent and wheat by 30 percent by 2050, it said.

Water shortages will also become more common in India as the Himalayan glaciers decline.

Nearly 100 million people in Asia will face the risk of floods from seas expected to rise between 1 millimeter (0.04 inches) to 3 millimeters (0.12 inches) annually, slightly higher than the global average.

For Australians and New Zealanders, the warming temperatures will be felt mostly through more extreme weather events.

"Heat waves and fires are virtually certain to increase in intensity and frequency," Kevin Hennessy, the coordinating lead author on the chapter for Australia and New Zealand, said in a statement.

"Floods, landslides, droughts and storm surges are very likely to become more frequent and intense and frosts are very likely to become less frequent," he said.

Rising temperatures, according the report, will also lead to a loss of a quarter of alpine ice mass in New Zealand, drops in agriculture production in southern and eastern Australia and eastern New Zealand, as well as the spread of tropical diseases such as dengue fever.

In the South Pacific islands, the rising sea level "is expected to exacerbate inundation, storm surge, erosion, and other coastal hazards, thus threatening vital infrastructure, settlements, and facilities that support the livelihood of island communities," according to the report.

Penehuro Lefale, one of the lead authors on the small-island chapter, said the rising temperatures will also hurt sectors ranging from tourism to agriculture and fisheries on many island nations.

"Climate change is likely to heavily impact coral reefs, fisheries and other marine-based resources of small islands of the Pacific," he said. "There is likely to be a decline in the total tuna stocks and a migration of these stocks westwards, both of which will lead to changes in the catch in different islands."

While the South Pacific islands will struggle to adapt to climate change, the report said Australia and New Zealand have "considerable capacity" to adjust.

The report said efforts to cut greenhouse gas emissions should be launched, but predicted immediate reductions would not offset climatic changes until at least 2040.

It also called for a range of adaptive measures including limiting new building along threatened coastlines, building corridors to allow threatened species to migrate, and improving water conservation.

Sustainable development policies with climate change in mind should be put into common practice, it said, and public food distribution networks, disaster preparedness, and health care systems should be improved to reduce the vulnerability of developing countries.