MELBOURNE, Australia – The United Nations challenged Monday and warned that many of the world's coral reefs could die as early as 2040 as a result of climate change.
Already, warming water has become more than two churches in the Great Barrier Reef, the world's largest coral reef ecosystem, covering more than 130,000 square kilometers and visible from space.
However, the Great Barrier Reef, despite its status, is not the only unique or threatened marine ecosystem in Australia.
Here are some other Australian ecosystems to remember:
The Great Southern Reef
Spans 27,000 square kilometers along the south coast of Australia, this viable sea forest could be decimated by the end of the century, according to a new study. The researchers found that warming water could kill up to 100 percent of the reef's crustaceans, which provides a habitat for fungi, crustaceans and fish. Reef also supports two of Australia's most valuable commercial fishery products: abalone and rock lobster.
Together with tourism at the Great Southern Reef, these fisheries contribute to the Australian economy a year to approximately $ 10 billion, or $ 706 billion. (According to some estimates, this is more than the revenue generated annually by the Great Barrier Reef.) And if about 70 percent of Australians live within about 30 miles of herring, many have never heard of it.
"The South Coastline is one of the most artificial, temperate ecosystems in the world," said Thomas Wernberg, Marine Science teacher at the University of Western Australia in Perth, and the author of the latest paper. "It's important not to forget about these other ecosystems."
Shark Bay on the west coast of Australia is the largest and most varied sea grass ecosystem in the world. These seagrasses provide habitat for fish, threatened green turtles and dugons, the only vegetarian marine mammal, which is dependent on the sea grass for food. Shark Bay is also one of only two places in the world with living ancient landfills of algae, called stromatolites.
But in the summer of 2011, a large seawater bridge killed about a quarter of Shark Bay's seagrasses. Apart from the loss of a valuable marine area, this shutdown also meant emissions of up to nine million tonnes of carbon dioxide, according to a paper published earlier this year. It was an "unrivaled event," said Oscar Serrano, a postdoctoral researcher in marine ecosystems at Edith Cowan University in Queensland and one of the leading authors of the study.
"It's a big loss, but the oceans are dynamic and the sea's grass meadows have the capacity to adapt," he added. "What bothered me most is that these heat waves are expected to increase both in size and length. If there is another large heat wave, this can have a more serious impact."
Every year hundreds of walks are gathering at Ningaloo Reef , off the west coast of the country. Unlike the Great Barrier Reef, Ningaloo is a close shore: "You can just snorkel away from the beach and see coral in a few minutes," said Verena Schoepf, Marine Science Researcher at the University of Western Australia.  So far, Ningaloo has avoided the kinds of bleaching events that have destroyed the Great Barrier Reef and left the coral there weak and susceptible to the attack of the crown of tower starfish stars. But global warming puts Ningaloo at risk of damping, according to the UN report, and rising sea levels can also reduce the reef's capacity to protect coastal communities from waves and erosion.
The Gulf of Carpentaria, in Australia's fourth north, is a remote and sensitive ecosystem of mangroves, coral, sea grass beds, clay crabs, fish and shrimps. Mangrove trees – which grow in saltwater – provide a orphanage for fish and wildlife and help prevent coastal erosion.
But the summer of 2016 – the same summer as the Great Barrier Reef experienced one of the worst bleaching events in history – extreme heat, drought and low sea levels led to an unprecedented killing of mangroves in Carpentarias mountains, where about 6 percent of the forest went lost. Like seagrasses, many columns also collide, and during the killing millions of tons of carbon were released into the atmosphere.
"The view has been that mangroves are tough and resilient and survive most things and they can, but there are limits," said Norman Duke, a professor and mangrove veterinarian at James Cook University in Queensland. "It's an alarm clock," he said.