Oct. 2 (Bloomberg) -- Australia's average temperatures may rise by about 1 degree Celsius (1.8 degrees Fahrenheit) by 2030 and by 3.4 degrees Celsius by 2070 unless greenhouse gas emissions are cut, the nation's weather bureau and science agency said.

Temperatures will be more extreme with ``substantially'' more days over 35 degrees Celsius (95 Fahrenheit), the Bureau of Meteorology and the CSIRO said today in a joint report. Rainfall will decrease and droughts and high fire-danger weather become more frequent under the ``high-emissions'' scenario, it said.

A United Nations panel of scientists last month said the world is ``very unlikely'' to avoid a warming of 2 degrees Celsius that may lead to droughts and floods and put millions of people at risk.

``The message is that global warming is real, humans are very likely to be causing it, and that it is very likely that there will be changes in the global climate system in the centuries to come, larger than those seen in the recent past,'' the report said.

Australia's average temperatures increased by 0.9 degrees Celsius since 1950, with ``substantial'' declines in rainfall in the east and southwest, according to the Climate Change in Australia report published online. 2005 was Australia's hottest year on record, said Scott Power, the weather bureau's principal research scientist.

Sea levels rose by about 10 centimeters (4 inches) from 1920 to 2000 at Australian coastal sites monitored by the government, the agencies found. The report was published by the weather bureau and the Commonwealth Scientific and Industrial Research Organization, known as CSIRO.

Rainfall Changes

Changes in rainfall are partly responsible for rising temperatures because of weather patterns such as the El Nino phenomenon that causes drought, Power told reporters at a presentation in Sydney today.

The report comes before Australia holds a general election this year and politicians try to woo voters with policies on tackling climate change. Prime Minister John Howard last week set a target for 15 percent of Australia's energy to come from renewable sources by 2020.

Australia will start a carbon emissions trading system in 2011 or 2012 and set a greenhouse gas reduction target next year, Howard said in June. Details of the system, including how emissions permits will be allocated, are yet to be determined.

Kyoto Treaty

Kevin Rudd, leader of the opposition Labor Party, has pledged to sign the Kyoto Protocol, the only international treaty to set targets for emission reductions. It binds 35 nations to curb carbon emissions by 5.2 percent from 1990 levels by 2012. Howard has joined President George W. Bush in refusing to ratify the accord.

``These projections give us a window into the future that we could be leaving our kids,'' said John Connor, chief executive of Australia's Climate Institute, in an e-mailed statement today. ``By taking urgent action now we can avoid the worst impacts of climate change and create a more hopeful future for our kids,'' he said.

Australia emitted 559 million tons of greenhouse gases in 2005, the most recent year on record, the government said in May.

China produced 6.2 billion metric tons of carbon dioxide from burning fossil fuels and producing cement last year, the Netherlands Environmental Assessment Agency said in June. That pushed it past the U.S. as the world's largest emitter.

To contact the reporters on this story: Angela Macdonald-Smith in Sydney at amacdonaldsm@bloomberg.net; Simeon Bennett in Singapore at sbennett9@bloomberg.net

Last Updated: October 2, 2007 04:00 EDT