The mystery behind climate change has finally been made clearer.

The Atlantic Ocean stalled global warming over the past 15 years by trapping atmospheric heat into its depths, according to a recent study.

The study just published in the journal Science gives the latest explanation for the apparent warming hiatus of the Earth's surface since the 1990s despite the rapid increase of greenhouse gas emissions.

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Author Kakit Tung from the University of Washington said it's important to distinguish whether ocean heat storage or not enough heat reaching the Earth's surface is responsible for the global warming slowdown.

Together with co-author Xainyao Chen of China's Ocean University, Tung searched oceans for the answer using a network of devices called Argo Floats that read ocean temperature and salt content down to 2,000 meters.

Data shows that deep regions of Atlantic and Southern Ocean stored more heat than any other ocean combined. This trapped heat could have resulted in rapid global warming if it had stayed on the surface. 

Tung said the results surprised them since previous theories pointed to the Pacific Ocean as culprit for hiding heat. The data shows otherwise and it's quite convincing, he asserted.

Researchers also noticed that heat content in regions shifted in 1999, about the same period when the hiatus started.

They suggested the sudden shift in salinity may have triggered the movement of heat to deeper waters. Recent observations show high saltiness at North Atlantic while deeper water on the same surface displays an increasing amount of heat.

When heavy water lies on top of light water, it plunges very fast and carries heat with it, said Tung.

The result is a slow moving current, which they called a "conveyor belt," that sinks heat almost 1,500 meters below the two poles.

The study concluded that the varying Atlantic Ocean circulation meant some 30 warmer years would be followed by 30 cooler years.

 Salinity-driven cycles that can store heat in the depths of Atlantic and Southern Oceans are re-occurring, Tung said. Historically, similar events have taken place every 30 years.

Researchers suggested the current global warming slowdown could last for the next 15 years. After this, rapid warming will return.

TagsAtlantic Ocean, global warming, Science