New research claims impact of greenhouse gasses on the oceans could linger for centuries after emissions are halted.
A newly released study is saying the greenhouse gasses released into the atmosphere are causing “thermal expansion” in the world’s oceans, and even if the release of the gasses could be suddenly cut off, the impact on the seas could last for centuries.
Thermal expansion is a process by which greenhouse gasses released into the air cause a rise in air temperatures, and a portion of the heat is absorbed by the ocean waters, causing them to expand in volume. This is not a new concept as climate models have been taking this into account for decades, while predicting rising sea levels.
But the new research, published in the Proceedings of the National Academy of Sciences, and cited in the Washington Post, says the process should be receiving more attention, and earlier work may have underestimated how long it takes for the process to reverse.
According to Susan Solomon, professor of environmental studies at the Massachusetts Institute of Technology, “If you’ve ever made a cup of tea on the stove you know that hot water expands. It’s simply basic physics, and it’s something that the planet can’t get away from.”
The research notes that different types of greenhouse gasses have longer life spans in the atmosphere, with carbon dioxide lasting for potentially 200 years, and gasses like methane having a life of only about 10 years or so. But the researchers climate models predicted the impact of the thermal expansion on the oceans could still be at 75 percent 100 years after the emissions stop.
Still more frightening, the levels of thermal expansion could be as much as 40 percent even after a period of 500 years. Of course, the longer the emissions continue, the worse the situation becomes.
The issue arises because the ocean water, which is cooled down at the poles, sinks to the bottom and flows towards the equator to be warmed. Warmer air temperatures cause the water to absorb more heat, and the process, known as overturning circulation, can last for hundreds of years before the water’s heat can be released back into the air.
The paper was written by Solomon and colleagues Kirsten Zickfeld, from Simon Fraser University, and Daniel Gifford, also of MIT.