The phenomenon of white corals globally has led scientists to worry that they will die massively.
In the October 8 warning, scientists from many prestigious agencies - including the US National Oceanic and Atmospheric Administration (NOAA), said they have now discovered white corals at the region of the northern Pacific, India, equatorial Pacific and western Atlantic Ocean.
"This is the third time we have recorded white coral phenomenon globally," Mark Eakin, NOAA coral expert, told Reuters.
According to Eakin and other experts, seawater warms up due to climate change and a mysterious hot array in the northeastern Pacific known as "The Blob" has destroyed coral.
"It is unclear how" The Blob "is related to climate change . It is still unknown , " Eakin said.
He also said countries can help save coral by limiting overexploitation and reducing pollution .
Coral is a place to nourish many fish species and create livelihoods for millions of people. Normally corals are colorful, their "bleached" (also called white corals) is a sign of death or decomposition.
Based on the current record high temperatures in many oceans, scientists predict more than 12,000 square kilometers of coral in the world will disappear this year.
The same warning was issued in 1998 and 2010 - both years are very hot and all happen with the El Nino phenomenon.