MADRID, Aug 21 (EUROPA PRESS) -.
A new research by experts at the University of Washington (UW) in the United States, and published in this week the journal Science, shows that the absence of heat on the surface of the Earth is plunged deep into the northern and southern Atlantic Ocean and is part of a natural cycle. Heating under the ocean surface explains why global average air temperatures have fallen since 1999, despite the increased presence of greenhouse gases trapping solar heat in the surface of the Earth.
After a rapid warming in the twentieth century, this century has seen so far very little increase in the average surface temperature of the Earth. This change has been proposed more than a dozen theories called hiatus in global warming, ranging from air pollution to volcanoes or sunspots.
“Every week there’s a new explanation for the paused –reconoce author Ka-Kit Tung, Professor of Applied Mathematics and Associate Professor of Atmospheric Sciences at the University of Washington-. Many previous papers have focused on the symptoms on the surface of the Earth, where we see many different and related phenomena. We look at the ocean to try to find the underlying cause. “
The results show that a slow moving stream in the Atlantic, which transports heat between the two poles is accelerated at the beginning of this century to the heat sink to nearly a mile (1,500 meters). “The finding is a surprise, since current theories have pointed to the Pacific Ocean as the culprit to hide the heat –resalta Tung–. But the data are quite convincing and prove otherwise.”
Tung Chen and co Xianyao, Ocean University of China, who was a visiting professor at the UW last year, used recent observations of deepwater temperatures Argo buoys showing the state of water at 6,500 feet (2,000 meters) deep. These data show an increase of heat dissipation around 1999, when the rapid warming of the twentieth century stopped.
“There are recurring cycles that are driven by salinity that can store heat in the deep Atlantic and Southern Oceans -argues Tung–. After 30 years of rapid warming, now is the time of the cooling phase. ” These experts identified that half of the rapid warming in the last three decades of the twentieth century was due to global warming and the other half to the natural cycle of the Atlantic Ocean which keeps more heat near the surface.
When the observations showed an alteration in the ocean cycle, circa 2000, the current began to heat sink deeper into the ocean, to counteract human-induced warming. The cycle begins when saltier and denser in the northern part of the surface of the Atlantic near Iceland the water, makes the water sink, changing the enormous speed of the current in the Atlantic Ocean that circulates heat worldwide.
“When the heavy to the light water top water comes, dives very quickly taking heat” sums Tung. Recent observations in the North Atlantic surface salinity record shows, according Tung, while at the same time, the deeper water in the North Atlantic exhibits increased amounts of heat.
The authors unearthed data history to show that the cooling in the three decades from 1945 to 1975, which made people worry about a possible start of an ice age was during a cooling phase. Temperature swings are a natural switch, so that during the heating period, the swift currents cause more tropical water moves into the North Atlantic, warming the surface and deep waters.
In the surface, this warming melts the ice, which eventually causes the upper water is less dense and, after a few decades, curbs the movement, which triggers a cooling phase of 30 years. This explanation implies that the current slowdown in global warming could last another decade or more, and then again fast heating.
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