The world’s largest reef almost died at the start of the Last Interglacial period some 129,000 to 121,000 years ago, a new analysis has found.

Rapidly rising seas resulting from melting glaciers as well as polar ice sheet nearly wiped out the reef during that time, according to University of Sydney researchers. These findings may offer a peak into the future of the embattled reef, which has suffered a catastrophic coral bleaching event last year.

Not A Far Cry From Last Interglacial

The reef proved to be resilient enough with the eventual, growth of shallow reef once the sea level rise stabilized during that time. But today, this isn’t the only challenge for the World Heritage site, which is also facing survival pressures involving rising sea temperatures, pesticide run-off, and dredging from mining works.

“This provides the first snapshot of this paleo-reef against a background of rapid environmental change, including possible mass ice-sheet collapse,” said Dr. Belinda Dechnik, lead author of the study.

Sea levels and temperatures were much higher during the Last Interglacial than they were right now, but today’s world could be headed in the same direction if carbon dioxide emissions (CO2) remain unchecked.

Coupled with official climate change predictions and with the lack of enhancements in reef management and human impacts, these sea-level issues could drown the reef for good, warned Dechnik, who highlighted the need to increase the reef’s resilience.

To probe the ancient reef layer’s conditions, the team analyzed 1970s samples and 2015 cored samples taken directly from the reef site. Likening the reef to a sponge cake, the team said that the modern reef found today is the last layer while the ancient one is the second-last layer, which has come so close to drowning due to major environmental impacts.

While not as drastic as the ancient one, future sea level increases from climate change could also prove just as significant, or as tall as 6 meters (19.6 feet).

The findings were discussed in the journal Global and Planetary Change.

Coral Reef Struggle

A team from the University of Miami also recently released a coral reef study, combining climate models with different scenarios — including the Paris climate agreement’s outcomes — in order to estimate the fate of the reefs in the coming century. Their discovery: reefs around the world will start to experience bleaching every year in 2043 on average.

They warned that this will lead to major changes in the reef ecosystems’ function, as well as massively reduce their capacity to provide fisheries, coastal protection, and other crucial goods and services to humans.

Ongoing observations on the damage to the Great Barrier Reef reveal dire results, specifically 67 percent of those along the northern regions already dying in the past nine months alone. Year 2016 saw the worst documented coral bleaching to the reef, with climate change seen as the most likely culprit for a great portion of the destruction.

But it’s not just coral bleaching, but also intense ocean acidity and physical damage that are all leaving the famed reef struggling to survive.