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Surface temperature has increased about 1 degree Celsius since 1910, the report said, and rainfall through the growing season for winter crops has dropped almost 20 percent in some regions. Sea levels are also rising as ocean temperatures warm, leading to higher chances of inundation and coastal flooding. Oceans absorb large amounts of the world's excess heat.
Extreme weather events are increasingly common, said Steve Rintoul, interim director of Australia's climate science center at the Commonwealth Scientific and Industrial Research Organization and an author of the report. And that trend will continue.
"Although a 1-degree-Celsius rise in air temperatures seems small, it is enough to shift base-line averages," Dr. Rintoul said, referring to an increase equal to 1.8 degrees Fahrenheit.
He added, "It increases the odds those events will happen."
The biennial report, by scientists at Csiro and the Australian Bureau of Meteorology, draws on data collected at Cape Grim, Tasmania, where greenhouse gases caught in the atmosphere are measured, and from a program called Argo that tracks temperatures and other conditions in the world's oceans.
Australia is viewed as a leading example of a developed country being hit hard by climate change, and the report hints at the complex effects the rest of the world may face as climate change alters weather patterns.
"The whole globe is subject to change," said Karl Braganza, of the Bureau of Meteorology, another author of the report. "It is sobering to look at other countries, countries like Bangladesh, or African nations, where their ability to deal with drought is much more reduced than ours."
Up to 75 percent of ocean warming occurred in the Southern Hemisphere, the report said. As oceans absorb carbon dioxide and water temperatures increase, they expand, contributing to a rise in sea levels. Warmer oceans have also prompted a shift in large-scale weather patterns, which in turn affects rainfall. Although precipitation across Australia varies year to year, Csiro said the recent drying out of southern Australia was the strongest recorded large-scale change in rainfall since national records began in 1900. Years with lower-than-average growing-season rain would be more frequent in some regions, the report said.
Rainfall in the southwest reached such lows that Perth, the capital of Western Australia, mostly relied on water from desalination plants, Dr. Rintoul said. Long-term averages have declined 19 percent since 1970, but that has accelerated to 25 percent since 1996. Perth, an isolated city on the far western coast, has a population of about two million.
Water that flows through streams and rivers also declined sharply. In the food-growing Murray-Darling Basin, in southern New South Wales and Victoria, stream flows were 41 percent lower than average, and in some parts of Victoria, they declined more than 70 percent.
The report also said that since 1993, sea levels to the north, west and southeast of Australia surpassed the global average. Ocean warming contributed to about a third of that rise, of about 20 centimeters, or 7.8 inches, since the late 1800s. The remainder was attributed to melting sea ice and changes to water stored on land.
The scientists, who said carbon dioxide emissions were largely because of the burning of fossil fuels like coal, refrained from urging the government to increase its commitment to lowering pollution targets. Australia has yet to ratify the Paris accord on climate change.
In August 2015, Australia agreed to an emissions cut of between 26 and 28 percent from 2005 levels by 2030. But state authorities have pushed ahead with plans for an immense coal mine in Queensland, inland from the Great Barrier Reef.
For almost a decade, Australia has fought bitterly over efforts to curb polluters. Two years ago, the country repealed carbon laws requiring large companies to pay for greenhouse gas emissions, a measure intended to penalize hundreds of its biggest producers of carbon emissions. During his successful campaign for prime minister a year earlier, Tony Abbott, then the leader of the Liberal Party, said the tax pushed up electricity prices for consumers. That claim contributed to his party's win. The emission targets that he put in place, derided as too low by environmental groups, remain in effect under his successor, Malcolm Turnbull.
Dr. Rintoul said historical emissions meant temperatures in Australia would continue to rise. Temperatures in the spring hit highs for three consecutive years starting in 2013, he noted. And agreements reached in Paris would not limit global warming to 2 degrees Celsius, he said, adding that carbon emissions were at peak levels in 2015 and would rise.
"We have to go further," he said.
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