The latest report from United Nations climate scientists focuses on the ocean - which is warmer, more acidic and less productive - as well as ice, largely sea caps and glaciers.

Melting could raise sea levels by 30 to 60cm by the end of the century if global warming is capped at two degrees, or by more than a metre if pollution rates continue on current trends.

Ms Ley said she "totally accepted" climate change was a huge pressure on oceans and the Great Barrier Reef.

But she said Australia was playing a major global role.

"I will stand in any forum and say it is probably the best managed reef in the world," she told Sky News on Thursday.

"People are coming to us to understand how best to manage their tropical reefs."

She said the government was addressing the challenges through sustainable use of marine parks, tackling plastics and ground-breaking oceans science.

Labor environment spokeswoman Terri Butler said the report should be a "science reality check for the prime minister and his climate-denying government".

"The release of this report could, and should, be the wake up call the Morrison government needs to address their woefully inadequate emissions reduction target and climate change policy," she said.

Australian Associated Press