Last week, the National Oceanic and Atmospheric Administration (NOAA) declared the third global coral bleaching event ever on record. The announcement came after a year of widespread coral damage that started in the north Pacific, expanding to the south pacific and Indian oceans before it reached Hawaii and the Caribbean.

Mark Eakin, NOAA's Coral Reef Watch coordinator, said that the coral bleaching is the result of climate change. Coupled with events, such as the current El Niño, coral bleaching and disease are the biggest and most pervasive threats to coral reefs worldwide.

Mark Eakin added, “We are losing huge areas of coral across the US and internationally. What really has us concerned is this event has been going on for over a year. Our preliminary model projections indicate it's likely to last well into 2016”.

According to NOAA estimations, around 95% of the US coral reefs are going to be exposed to ocean conditions by the end of 2015, causing corals to bleach. NOAA estimated that in the Pacific Ocean, coral reefs have been declining at a rate of about 2% a year. Scientists have warned that coral reefs are likely to be seen for just 40 to 50 years, and then they will be completely gone.

Warming waters, even by just one degree, causes coral bleaching due to which, corals have to expel the symbiotic algae in their tissues that turn them white or pale. The coral loses its key source of food without the algae and become increasingly susceptible to the disease.

"We need to act locally and think globally to address these bleaching events. Locally produced threats to coral, such as pollution from the land and unsustainable fishing practices, stress the health of corals and decrease the likelihood that corals can either resist bleaching, or recover from it," said Jennifer Koss, NOAA Coral Reef Conservation Program acting program manager. "However, to solve the long-term, global problem, we need to better understand how to reduce the unnatural carbon dioxide levels that are the major driver of the warming."