At a Glance

The damage done to the reefs has been more significant than previously envisioned, scientists say.Scientists fear "zero prospect of recovery" for previously damaged reefs.

Two-thirds of Australia’s Great Barrier Reef have been found to be severely bleached, scientists say.

This is the second year in a row that theunderwater ecosystemexperienced such asevere bleaching event, at the ARC Centre of Excellence for Coral Reef Studies at James Cook University, located in Townsville, Australia, who analyzed 5,000 miles of aerial survey data.

"The combined impact of this back-to-back bleaching stretches for 900 miles, leaving only the southern third unscathed,"Terry Hughes, lead author of the survey, said in a statement.

"Clearly the reef is struggling with multiple impacts," Hughes added. "Without a doubt the most pressing of these is global warming. As temperatures continue to rise the corals will experience more and more of these events:1 degree Celsiusof warming so far has already caused four events in the past 19 years."

Another researcher who helped collect the bleaching stats, James Kerry, had ominous predictions for the future of the reef.

"It takes at least a decade for a full recovery of even the fastest growing corals, so mass bleaching events 12 months apart offers zero prospect of recovery for reefs that were damaged in 2016," Kerry said in a statement.

Coral bleaching occurs when corals are stressed by changes in their environment,leading them to discharge tiny photosynthetic algae, known as zooxanthellae.

Danielle Dixson, a marine biology assistant professor at University of Delaware and expert on coral reefs,told weather.com in an phone interview that the heat of the ocean —fueled by rising global temperatures and compounded by— brought signifcant stress to theUNESCO World Heritage Site.

This inforgraphic displays the surveyed coral reefs from last year and 2017. Red circles illustrate extensive bleaching, green circles represent minimal damage.

(ARC Centre of Excellence for Coral Reef Studies)

"With what they're seeing right now, the waters are way too hot," Dixson said. "It's more the sustained heat. Ifthe water is hot for a couple of days, the corals can cope.Ithink if it's been10 days, the ability to cope is going to be significantly reduced. When a coral bleaches, it doesnt necessarily die, it's able to absorb algae that lives in its tissue, but if it stays bleached for too long, the chances of that happening is less and less."

(PHOTOS:Stunning Photos of Coral Bleaching in Okinawa and New Caledonia)

The news of the extensive damage has had environmentalists scramblingto find ways to save the endangered reefs.

Dixson noted that suggestions in the past have included using shade cloth to protect corals from heat stressas a potential remedy but felt the sheer magnitude of the underwater ecosystem was too enormous for such methods to be effective.

"That's very small scale type stuff considering you can see it from space," she explained."It's a huge amount of area. There's not a way to fix what's happening right now, we can't cool the entire Great Barrier Reef down. It'sa guessing game to see which corals can survive, and which ones can adapt."

Georgia Tech climate scientist Kim Cobb told weather.com in a phone interview that the damage done to the reefs has been more significant than previously envisioned.

"Our community has woken up quite abruptly to what we had expected to be 20 to 30 years out, it's here now," she said. "It's a sobering new reality.Many different portions of the ecosystems touch the coral reefs, you're kicking up a nursery of the ocean that's providing safety to fish species, this will be a big hit to the ocean."

Cobb suggested that the report heldopportunities and lessons for scientists,suggesting that breeding coral to be as resilient as possible should be considered as a potentialsolution."It's really about damage control," she noted.

David Suggett, chief marine researcher at the University of Technology Sydney The Guardianthat for the reefs to survive they need to remain interconnected.

"It's that connection ultimately that will drive the rate and extent of recovery," Suggett told the newspaper. "So if bleaching events are moving around the [Great Barrier Reef] system on an annual basis, it does really undermine any potential resilience through connectivity between neighboring reefs."

Despite the discussion of possible cures, Dixson remained disturbed by the dire bleaching report.

"It's really scary," she acknowledged. "I've been studying the impacts of humanimpacts on coral reefs my entire career, I never thought Iwould never be able to show my kids the coral reefs, but now it's starting to seem like it's a potential if we dont act. ... A lot of this is trying to predict the future."

Cobb provided some hopeful perspective amid the gloomy news for the corals.

"In geologic time, reefs will prevail, reefs will regrow, the question is what reefs we want our kids snorkeling on, that's the real question we as a species have to answer," she said."It's about what decisions we make now. We can make a difference and we can save those reefs going forward, or we can choose to let it rip."

MORE ON WEATHER.COM: Great Barrier Reef Bleaching Continues