The amount of heat being absorbed by the oceans has dramatically ramped up in the last two decades, according to new research. The world’s oceans are thought to have absorbed 90 percent of the excess heat energy produced through man-made climate change, as well as around a third of all the carbon pumped into the atmosphere. This is already having dramatic impacts on the distribution of fish, which are shifting to more northern and southerly latitudes, as well as the health and survival of coral reefs.
With the ocean taking the brunt of the heat, this warming has not only been limited to the ocean’s surface but is sinking to deeper depths. The new study has found that the water below 700 meters (2,300 feet) in depth is actually taking up 35 percent of all the heat absorbed by the oceans. This could have profound and unknown consequences as the warming water could impact deep water currents and processes that influence weather and climate.
It has already been announced that the oceans are going through a third global coral bleaching event, caused by warming waters and ocean acidification. Ethan Daniels/Shutterstock
Most studies have looked at how climate change has been affecting the surface temperature of the oceans, but this latest research, published in Nature Climate Change, has plunged a little deeper. Starting with data first collected by the research ship Challenger in the 1870s, the researchers tracked the changes in the ocean temperatures to a depth of 2,000 meters (6,500 feet) to calculate exactly how the heat has fluctuated during the past 150 years.
The study shows that between the years of 1865 and 1997, the world’s oceans absorbed around 150 zettajoules of energy, and then another 150 in the following 18 years. To put this into perspective, 150 zettajoules of heat energy is equivalent to one Hiroshima-sized bomb being detonated every second, for 75 years. These numbers far exceed any amount of energy that would be naturally produced, and are a direct result of human-driven climate change.
The authors note that it is not the raw numbers that worry them, but the rate at which it is happening, with the last 20 years being of particular concern. Their data shows that the amount of energy being trapped in Earth’s climate system is accelerating, and this could have knock-on effects for those surviving on the land, too. As the oceans absorb more heat, it limits the amount they will be able to take up in the future, meaning more stays in the air and on the land surface.
