New Delhi, Sept. 26 -- In a wake-up call for world leaders, the Intergovernmental Panel on Climate Change (IPCC) has warned that oceans are projected to transition to "unprecedented" conditions, marked by an increase in temperatures, higher acidification and a decline in oxygen levels over the rest of the 21st century.

Marine heatwaves and extreme El Nino and La Nina phenomena will become frequent, IPCC said in a report released on Wednesday.

Extreme sea level events that are historically rare, occurring once per century, are projected to occur at least once a year in many locations, particularly the tropical region, by 2050.

In India, parts of the West Bengal and Odisha coasts are likely to experience such events annually by 2075, accor...