Global warming is real, man made, and could cause the world's sea level to rise a metre by the end of the century, much higher than previously thought, according to the federal government's Climate Commission.

Melbourne faces extreme and more frequent flooding, while higher sea levels are already "bad news" for fragile areas including Kakadu and the Great Barrier Reef, says Commissioner Will Steffen.

Rising sea levels ... climate change.

The commission's first major report, The Critical Decade, is released today.

It also says this year's Queensland and Victorian flooding ''raised the question of a possible link between the floods and human-induced climate change''.