Hawaii scientists have started to prepare for a major coral reef bleaching event due to warmer-than-average ocean temperatures, officials said.

The National Oceanic and Atmospheric Administration analyzed ocean temperatures across the islands have increased by 3 degrees Fahrenheit, The Honolulu Star-Advertiser reports .

At the same time, overall ocean temperatures have increased before the expected peak summer temperature arrivals in September, scientists said.

Coral bleaching occurred before in 2014 and 2015, but scientists are already seeing signs of a worse event at Kealakekua Bay on Hawaii island and at Kaneohe Bay and Hanauma Bay on Oahu, scientists said.

Coral bleaching is a change from normal coloration of browns, yellows and greens to a nearly white color because of increased exposure to environmental stressors, including temperature increases, experts said.

Coral reefs are important for marine habitats, have cultural, recreational and economic benefits, and also provide protection for coastal shorelines during storms, scientists said.

The public can help document the expected coral bleaching event by reporting sites of white coral, experts said. They can also help alleviate other stressors by not touching corals while snorkeling, swimming or diving, not standing on them, and preventing pollutants found in some fertilizers and detergents from getting into the ocean.

"We know this bleaching event is coming, and it's probably going to be worse than the ones we experienced four and five years ago," said state Division of Aquatic Resources Administrator Brian Neilson. "We're asking for everyone's help in trying to be proactive and to minimize any additional stress we put on our corals."