A NASA study of ocean temperatures from 2003–2012 found that despite increase in greenhouse gases, the global surface temperature is cooling down, a strange phenomenon that climate contrarians term as merely a “hiatus.”
The study said one of the leading explanations could be that extra heat was being stored in the ocean.
The Pacific Ocean is trapping ocean heat energy with shifting patterns and now Indian Ocean is also joining the process, said the NASA study based on ocean temperature measurements in recent years.
While the trapped heat beneath the ocean is temporarily slowing down the surface temperature, though greenhouse gases are generating more heat energy on earth. Ever since the the turn of 21st century, the heat is increasingly trapped in the ocean waters and the surface temperature is cooling down but temporarily, observed the study.
“Greenhouse gases continued to trap extra heat, but for about 10 years starting in the early 2000s, global average surface temperature stopped climbing, and even cooled a bit,” said Josh Willis of NASA’s Jet Propulsion Laboratory (JPL), Pasadena, California.
JPL researchers Willis, Veronica Nieves, and Bill Patzert have found a specific layer of the Indian and Pacific oceans between 300 and 1,000 feet below the surface has been accumulating more heat than previously thought and the movement of the warm water has affected surface temperatures. They used ocean temperature measurements from a global array of 3,500 Argo floats and other ocean sensors.
In their paper published in the journal Science, the researchers said the pattern was typical to the Pacific Ocean in the past up to 2003 and now it is visible in the Indian Ocean too. Attributing the new phenomenon to strong trade winds and other climatic changes, they said warm water is piling up in the upper 1,000 feet of the western Pacific, affecting Asia and Australia.
“The western Pacific got so warm that some of the warm water is leaking into the Indian Ocean through the Indonesian archipelago,” said Nieves, who is the lead author of the paper.
What is puzzling to the scientsts is the fact that the air temperature over the oceans is cooling down in the last one decade. Cooler surface temperatures could be due to a long-known climatic pattern called the Pacific Decadal Oscillation, they said. Or the movement of the warm Pacific water westward could have pulled heat away from the surface waters of the central and eastern Pacific, resulting in unusually cool surface temperatures in this region, they added.
The Pacific Decadal Oscillation moves in a 20 to 30 year cycle and the current pattern may be changing to the opposite phase, with observations showing warmer-than-usual water in the eastern Pacific, they explain in the paper. But the surge in global surface warming is definite, said Nieves.