The warming is also changing currents and altering weather systems at a speed wildlife cannot keep up with.
An international team of 14 scientists examined data that stretched back to the 1950s around temperatures from the ocean surface to the depths of 2,000 meters. The results of their study, which was published in the journal Advances in Atmospheric Sciences, also showed that the oceans are warming at an increasing speed.
Their findings are alarming. According to the report, the last five years have been the hottest year on record. Lijing Cheng, the paper's lead author and an associate professor at the International Center for Climate and Environmental Sciences at the Chinese Academy of Sciences, said the ocean temperature had risen 0.075 degrees Celsius above the average in 2019.
"There are no reasonable alternatives aside from the human emissions of heat trapping gases to explain this heating," Cheng said, adding that to reach this temperature, the ocean would have taken in 228,000,000,000,000,000,000,000 -- or 228 sextillion -- joules of heat.
"The Hiroshima atom-bomb exploded with an energy of about 63,000,000,000,000 Joules," Cheng said. "I did a calculation ... the amount of heat we have put in the world's oceans in the past 25 years equals to 3.6 billion Hiroshima atom-bomb explosions," he added.
The oceans have become one of the easiest ways to measure the impact of climate change. Much of the heat from the sun gets trapped in the water and the pollutants have changed the water composition, making microplastics a major part of the chemical make up. Rising temperatures also mean ocean waters have less oxygen and are becoming more acidic, which has a major impact on nutrients that feed marine wildlife.
"If you want to understand global warming, you have to measure ocean warming. We are now at five to six Hiroshima bombs of heat each second," John Abraham, one of the authors of the study and a professor of mechanical engineering at the University of St. Thomas in Minnesota, said. "It is critical to understand how fast things are changing."