New research has caught a glimpse of what happened to the Great Barrier Reef when it was brought close to death over 100,000 years ago.

Marine geologist Dr Belinda Dechnik, from the University of Sydney, is lead author of a new report examining ancient core samples drilled from deep within the reef.

The core samples provide data on the reef from a period known as the Last Interglacial, after the second last ice age.

At that time, around 129,000 years ago, water from melting ice sheets flooded coastlines around the world and almost drowning the reef.

“The past is the key to the present — the reef almost drowned just prior to 129,000 years ago,” Dr Dechnik told the ABC.

“Sea levels were rising very rapidly and the reef was not able to keep up.

“When sea levels had stabilised, the reef was able to catch up and re-establish itself.”

Dr Dechnik said the conditions back then are similar to those facing the reef today, though there are some extra variables – increased sediment and higher ocean acidification.

“Sea levels were slightly higher, sea surface temperatures were slightly warmer than they are today, and they're in the levels that we have projected in the future,” she said.

“We're not sure at what point and at what level these different impacts [such as sediment and ocean acidification] are going to come together and be too much for the reef.

“The Great Barrier Reef 125,000 years ago wasn't dealing with impacts from humans.

“We didn't have terrestrial pesticide run-off, we didn't have to worry about dredge spoils, so these are additional factors that the reef will have to overcome.”

The Queensland and Federal governments have been trying to improve water quality and the health of the reef through the 35-year plan Reef 2050 Plan.

Meanwhile, Dr Dechnik says the latest findings show why boosting reef resilience is worthwhile.

“We know that they can come back — they are resilient species and if we take the right measures they'll be around for the next generation,” she said.